swift double question mark

It returns the left-hand operand if the operand is not null; otherwise it returns the right hand operand. You can see this youtube video which demonstrates the whole thing practically. Hello, Swift 4! To ensure that the value isn't nil use a ! in your code — just that you should use it mindfully, and never make it the default option. By which I completely understood the "why to use ?? Is there a reasonable recovery path your code could take in the nil/error case? Link between bottom bracket and rear wheel widths. and ?? I like how you simplified its meaning to "null coalescing operator". The "nil check" still has to be done at runtime, the sole difference being that a runtime error wil be thrown in case no value is present in the Optional. The one thin not touched upon is that you can actually use it to throw an exception. Get nth character of a string in Swift programming language. So the docs talk about using ! I've only corrected the spelling of "ternary" but really the operator you mean is the conditional operator. The body of the minMax(array:) function starts by setting two working variables called currentMin and currentMax to the value of the first integer in the array. Can Pluto be seen with the naked eye from Neptune when Pluto and Neptune are closest? Another useful article about the implicitly unwrapped optional use for the exclamation mark: "Swift and the Last Mile" by Chris Adamson. You get a, @gnasher729 As the answer states, it circumvents the. To put it simply, exclamation marks mean an optional is being unwrapped. access the System.Nullable.Value property is an invalid operation if the type This prevents the object from being recreated every time. [) that is an operator that many times it is used in conjunction with ?? Is blurring a watermark on a video clip a direction violation of copyright law or is it legal? Why is it necessary? in Swift is used to denote an optional value either contains a value or contains nil to indicate that the value is missing. Press question mark to learn the rest of the keyboard shortcuts. Question marks after a type refer to Optionals, a way in Swift which lets you indicate the possibility that a value might be absent for any type at all, without the need for special constants.. It’s used in the same situations you’d explicitly return nil in Objective-C, when there is no object to be returned, or for values that are not objects, constants such as NSNotFound. In such a case, one would like to be able to examine the instance to ascertain whether a value is indeed present in the database. Thus exclamation mark holds two different usages, Next Recommended Reading Replace Double Quotes to Single Quotes in C# How can internal reflection occur in a rainbow if the angle is less than the critical angle? when we take just the English meaning of coalesce, we could expect the result to be some kind of union, or merge, of the arguments. Thus in order to declare a variable whose value isn't initially determined we use a '?'. is used during the declaration of a property, as it tells the compiler that this property is optional. instead. The first is when the instance represents a value in a database. This language design forces the nil case to be handled explicitly, which I suppose improves safety over Obj-C (where it is easy to forget to handle the nil case). I misunderstood a little the meaning of unwrapping at that time. Perhaps Apple might comb through their frameworks in the future, removing the uncertainty of implicitly unwrapped ("probably never nil") parameters and replacing them with optional ("certainly could be nil in particular [hopefully, documented!] So, if formsAuth is null, it will return new FormsAuthenticationWrapper(). (Question Mark vs Exclamation Point) Swift, in my opinion, is a huge improvement over Objective-C. Why is that value optional/failable? Initialize only on the first get, if it´s not set before. An optional contains a value or it doesn't. How to check if a double is a whole number in swift? The second statement would cause an exception to be thrown because any attempt to Thus, types constructed from Difference between single and double ? constructs has a ? If you use an exclamation mark in Swift, … Once I grasped that, all of the other ?, ! @Moritz. The two question marks (??) Should I hold back some ideas for after my PhD? which is separate to Foo, and that prevents funcs which accept type Foo from receiving a nil value, but at a low level an optional value isn't a true object because it has no properties or methods; it's likely that in fact it is a pointer which may by NULL(0) with the appropriate test when force-unwrapping. Re: last sentence in the q - for future ref, SymbolHound is great for this kind of thing e.g. Tangential but related: It's now in Swift, but it's very different: "Nil Coalescing Operator", At least now, it's easy to search it, even if you don't know the name, I just googled. @MSalters, keep in mind this feature is available only in C# 8 or more. But I still think that the unwrapping is code unwrapping and not memory based unwrapping as using enum. Yes it does, but the point is that by default Swift tries to catch errors at compile time. "is the compiler going to throw an error" - no it still works fine returning the value as expected. Let's take a simple example − If you see the English meaning of coalescing it says “consolidate together”. Now after 4 years I believe the meaning of unwrapping here is to expand the code from its original compact form. Where is the antenna in this remote control board? ), this refers to the "wrapped" enum (Some/None), not the value itself (T). How is it different from just doing the following: I'm very new to the Swift language. In the examples given in the article, Apple have chosen to declare the types as implicitly unwrapped, making the calling code more convenient, but less safe. Thanks everybody, here is the most succinct explanation I found on the MSDN site: The two question marks (??) Some of the examples here of getting values using coalescing are inefficient. to unwrap is sometimes not recommended see this Q&A. In Java this would be the equivalent of a NullPointerException or NPE for short.Kotlin's type system is aimed to eliminate NullPointerException's from our code. The unwrapping has nothing to do w.r.t performance. The ?? Some big picture perspective to add to the other useful but more detail-centric answers: In Swift, the exclamation point appears in several contexts: Every one of these is a different language construct with a different meaning, but they all have three important things in common: When you use ! Posted by u/[deleted] 5 years ago. Why doesn't ionization energy decrease from O to F or F to Ne? definitely has a value; please use it.” This is known as forced unwrapping of the optional’s value: Source: https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/TheBasics.html#//apple_ref/doc/uid/TP40014097-CH5-XID_399, If john were an optional var (declared thusly), then it would be possible for john to have no value (in ObjC parlance, nil value). The compiler will interpret this line as: The compiler will interpret this line as simply: Hence, using ! Join Stack Overflow to learn, share knowledge, and build your career. Maybe the ! is for speed? After reading this answer and some of Apple's example swift code, it really seems to me that in this tradeoff between safety and productivity, usually it's best to be on the safer side. operator is called the null-coalescing operator. It's short hand for the ternary operator. Using the Null Coalescing Operator this can be written: which can also be written with the shortened syntax: It's a null coalescing operator that works similarly to a ternary operator. It is more concise. i have corrected it. What does a question mark mean in C# code? I'd also found the following link that explains this. A lot of things in Swift are written using Generics. The bang or exclamation mark hints at potential danger. If you see the English meaning of coalescing it says “consolidate together”. Your answer is great because I understand, This doesn't seem to be true anymore. indicate that its a Coalescing operator. ISBN 0-672-32948-4. of this. If you use it as an optional, it unwraps the optional and sees if something is there. 5 comments. EDIT: And this is a cool feature from another question. IOS Swift, difference between someString! When such a variable is declared, to use it as a part of some expression one has to unwrap them before use, unwrapping is an operation through which value of a variable is discovered this applies to objects. Very few usages stand up to scrutiny. Potentially dangerous to chain these maybe. Reverse Engineering Stack Exchange is a question and answer site for researchers and developers who explore the principles of a system through analysis of its structure, function, and operation. Ans: The question mark ? used, because Person itself does have a member of apartment, As a future discussion on why using ! “Once you’re sure that the optional does contain a value, you can access its underlying value by adding an exclamation mark (!) it still returns the actual value. Exclamation marks don't circumvent any safety checks. That generic type definition is System.Nullable, which constrains the generic type arguments that may be substituted for T to value types. your coworkers to find and share information. I tried to answer based on my understanding of the concept. If john is an optional you must use the exclamation point to access its properties because the compiler must know that it isn't nil. I dont know is it so ? vs someString? Am i causing any problem or is there anything wrong in my answer ? It only takes a minute to sign up. then you can ... what it does under the hood is : Optional.Some(Person(name: "John Appleseed")), Had you defined var john: Person instead of: var john: Person? Is the ! See here. As we discussed yesterday, the question mark hints at an uncertainty. It's defined in section 7.12 of the C# 3.0 language specification. If you use it in an if-else statement is is code for NOT. But the cool thing about it is you can chain them, like other people said. is used during the declaration of … What do two question marks together mean in C#? :-). At a high level there is a type Foo? rev 2021.1.18.38333, Stack Overflow works best with JavaScript enabled, Where developers & technologists share private knowledge with coworkers, Programming & related technical career opportunities, Recruit tech talent & build your employer brand, Reach developers & technologists worldwide. Others have described the Null Coalescing Operator quite well. It is basically a shorthand for the ternary conditional operator when used to test for nil. Instead of the private variable remaining null and a new object getting created on every request, this ensures the private variable is assigned if the new object is created. This is often used to trap errors that would otherwise crash the program. So if str1 is null it will try str2, if str2 is null it will try str3 and so on until it finds a string with a non-null value. That key should be placed on the right beside the punctuation slider, and made into a question mark. What are the correct version numbers for C#? at the end of an object says the object is an optional and to unwrap if it can otherwise returns a nil. to the end of the optional’s name. But you can run the code fine without it (a forth option for your list - implicit unwrapping) AND without checking first. when you know for sure it can be unwrapped. You can see this youtube video which demonstrates the whole thing practically. Please don't write answers that are not adding anything that has not already been covered by previous answers. In general swift doesn't allow us to use a variable which isn't initialised, as this may lead to crashes or unexpected reasons and also server a placeholder for backdoors. So if you try to assign a nullable value type to a non-nullable value type Kotlin's type system is aimed at eliminating the danger of null references from code, also known as the The Billion Dollar Mistake.One of the most common pitfalls in many programming languages, including Java, is that accessing a member of a null reference will result in a null reference exception. Just like the answer of Ashley above, think about it as a present which could contain nothing in it. What does the [Flags] Enum Attribute mean in C#? The reason is that swift arrays are value types (implemented as structs) and not reference types (i.e. UPDATE: in Swift? (Paraphrased). This enum describes whether the variable holds a value (Some(T)), or not (None). It's very handy, particularly because of the way it works when it's used multiple times in an expression. The article explains that this is a pragmatic measure by Apple used to declare the types used by their Objective-C frameworks which might contain nil. Is crashing your program really the best option if the ! You can declare optional variables using exclamation mark instead of a question mark. is there to provide a value for a nullable type when the value is null. if you use Enhance Ability: Cat's Grace on a creature that rolls initiative, does that creature lose the better roll when the spell ends? One is when using println. Right Now I have to hold on the period button to get it. What is the difference between String and string in C#? To declare a variable which will be optional and will receive value definitely later Unless otherwise specified, the default inferred type of a floating-point literal is the Swift standard library type Double, which represents a 64-bit floating-point number. You only want to call the method if the variable is null. Perhaps a smart idea would be to regroup those, and question mark can have it's slider too, giving the exclanation mark as the first pop-up choice, and the upside-down question-mark … (As of this writing, the entire Siesta framework has exactly two instances of it.). ", Windows communication foundation unleashed By Craig McMurtry be empty. When array1 is assigned to array2, a copy of array1 is actually created and assigned. Archived. Do the benefits of the Slasher Feat work against swarms? = john where jack is also an optional or var jack: Person = john! to me. I think it originated in Smalltalk, where it has been around for many years. If you want the actual value of that variable, you must unwrap it, using one of the three methods above. The question mark makes a property optional if declared. OK. john is an optional var and it can contain a nil value. The following statement will assign the first non-null Answer# to Answer (if all Answers are null then the Answer is null): Also it's worth mentioning while the expansion above is conceptually equivalent, the result of each expression is only evaluated once. (Nullable). In English, it means "If whatever is to the left is not null, use that, otherwise use what's to the right.". The big piece of the puzzle that I was missing (not directly stated in the answers - at least not at the time of writing this) is that when you do the following: that does NOT mean that "john is of type Person and it might be nil", as I originally thought. and non-evaluating versions (??) or index (? double ?? USING Exclamation mark indicates that variable must consists non nil value (it never be nil). What is the technical difference between ? In fact later on the docs talk about implicitly unwrapped optionals using the below example: @RichardWashington You're confused for good reason! In my playground john.apartment = number73 does not compile, you must specify john?.apartment = number73. Thanks! then you would have no longer needed to have the ! It's really great that you included examples in your post, although the question was looking for an explanation of what the operator is or does. in swift is called nil coalescing operator that finds if optional has no value then it uses a default value. The question mark indicates that the value it contains is optional, meaning that it might contain some Int value, or it might contain no value at all. Meaning ! Apparently, there are at least a couple of instances where unwrapping of optionals is not required. @vitule no, if the second operand of the null coalescing operator is non-nullable, then the result is non-nullable (and. & ! You actually mean such: Does the above enum have any property named apartment? What should I do? I have read whole this thread and many others but I can't find as thorough answer as this is. I like this explanation because it has a diagram, and then the last sentence explains it in such simple terms! There other situation in which you'd see an exclamation mark is on a type, as in: This is roughly equivalent to accepting an optional with a forced unwrap, i.e. I'm not sure about this explanation. If it is not an optional you can't use the exclamation point. Those are the times to use force unwrapping. in Swift: Single ? Sign up to join this community It's hard to look up in Google. In production, use guard let or if let to deal with the situation of no-value and void hard crashes. Therefore, one can write: The C# programming language provides an abbreviated syntax for declaring types hide. Double space, question mark, and delete bad swipe Answered. ): 2. If you can't answer this question, then continue reading: To understand you may need super-basic level of understanding of Generics. is used if john is not an optional. For example below is a simple coalescing code which chains four strings. The property may hold a value or not, in the latter case it's possible to avoid runtime errors when accessing that property by using ?. 2. Instead, it too often means, “this value was optional and I didn’t really think too hard about why it could be nil or how to properly handle that situation, but adding ! But let me add more to what the video says. What does an exclamation mark in a property in Swift language? constructed from System.Nullable has not been assigned a valid value of T, which has not happened in this case. otherwise, if variable1 == null, set variable2 to 100. Swift provides type safety by providing 'optional value'. at the end of the var name. thanks for the feedback. If I were to unwrap it, the program would crash and Xcode would tell you you tried to unwrap an optional with a value of nil. You get back the value or nil if nil. Declaring a type as optional (using ?) Coalescing operator returns the first NON-NULL value from a chain. What does an exclamation mark mean in the Swift language? I want to know if it can be fixed. But there is a long standing predecessor, the t-sql. How does one generate a random number in Apple's Swift language? What's the word for someone who awkwardly defends/sides with/supports their bosses, in a vain attempt to get their favour? The exclamation point basically tells the compiler "I know this has a value, you don't need to test for it". How to check if a double is a whole number in swift? in the wild, it's rarely used so mindfully. So x1, x2, x3, and x4 could be Nullable types, example: sounds like wrapping ViewState with a property on a UserControl. Neither of these is actually correct, although in a roundabout way the first one is close. share. However if you unwrap it ie do person! @CodeBlend, it's not dangerous. Used to test for null before performing a member access (?.) The ! How to avoid force unwrapping a variable? It is an innovative ... What is the significance of “?” in swift? So wrap here doesn't mean it is memory wrapped, but it means it is code wrapped, in this case it is wrapped with an if statement, and because Apple pay close attention to performance in runtime, they want to give you a way to make your app run with the best possible performance. is optional right now and has no value but will receive a value in later in its lifetime. Why doesn't the null-coalescing operator work in this case? Thanks for visiting and working through these questions! Also it means removing the vagueness around that object, as we are not sure by definition if it is nil or not. If you've come from a C-family language, you will be thinking "pointer to object of type X which might be the memory address 0 (NULL)", and if you're coming from a dynamically typed language you'll be thinking "Object which is probably of type X but might be of type undefined". : You can use this to have a method which technically accepts an optional value but will have a runtime error if it is nil. Looking at the Xcode6 Beta header definitions didn't reveal to me anything about this magic. Here's some Ruby: Nothing dangerous about this. In practice, it doesn't truly behave like that because the work is done by the compiler. made it compile … so my code is correct, right?”, Beware the arrogance of the exclamation point. If you’re a developer out there who’s never made an iOS app, now is … we use "!". Above descriptions avoids too much of technical stuff, i hope. It can be the correct one: in mission-critical code where you have thought hard about your code’s invariants, it may be that bogus output is worse than a crash. What happens to a photon when it loses all its energy? Here, even-though 'hw' is a string, it can't be used in an if statement like in objective C. The ! Use this if you know that john is not nil. Even having … save. If you call this on a nil optional, you'll get a runtime error. Thank you. We are not given a guarantee hence the question mark. What is the question mark ? when you say var john: Person? Optionals included, The code below has been made available from this Stanford video. Operator - MSDN. promises the compiler that john is not nil then unwraps the optional to get john's value and accesses john's apartment property. where jack is a Person and is not nil, Right but, in the original example, doesn't the fact that I'm dereferencing the. Just because no-one else has said the magic words yet: it's the null coalescing operator. site design / logo © 2021 Stack Exchange Inc; user contributions licensed under cc by-sa. Coalescing operator returns the first NON-NULL value from a chain. Stack Overflow Public questions & answers; Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Jobs Programming & related technical career opportunities; Talent Recruit tech talent & build your employer brand; Advertising Reach developers & technologists worldwide; About the company When "wrapped", the value of an Optional variable is an enum with two possible values (a little like a Boolean). Would a vampire still be able to be a practicing Muslim? I don't get this. What do the two question marks mean, is it some kind of ternary operator? In Swift, what does the ! Ultimately I would love the user to "lock in" an answer for the question then pretty next question or previous question to go through the questions and then submit all the answers. Another useful article about the implicitly unwrapped optional use for the exclamation mark: "Swift and the Last Mile" by Chris Adamson. While. Are you saying that if john is nil, and I go. of doing this is. 2. Not all valid code fits into the box of Swift’s compile-time type system — or any language’s static type checking, for that matter. If so, code it. It would have been a god-send if it worked for empty strings as well :). In fact, it is beautiful. In your example, "x" is of type "int?" If you know or think you know that this variable cannot contain nil you can remove that check by using the exclamation mark. in Swift? This hints at an important aspect of the ?? Operator” or “Double Question Mark Operator” This last week I was introduced to quite a funky little operator in Swift called the Nil Coalescing operator . But let me add more to what the video says. site design / logo © 2021 Stack Exchange Inc; user contributions licensed under cc by-sa. Instead…. "Get used to cold weather" or "get used to the cold weather"? This is important if for example an expression is a method call with side effects. That’s a dangerous assertion. not unwrapped: did you mean to use '!' It makes it easy to comprehend and boosts my confidence in use. In cases where a single test for null is required, the shortened syntax ? you will get a compile-time error. Functions are actually a special case of closures: blocks of code that can be called later. A notable exception I've found is when Apple uses the forced unwrapping for UI elements, which makes sense because first, UI elements are usually optional when involving a storyboard (as they are not assigned a value programmatically), and second because they are almost never nil unless their containing view controller is nil, in which case this discussion if moot. Why do small patches of snow remain on the ground many days or weeks after all the other snow has melted? More info can be found in Apples documentation, which can be found here: https://developer.apple.com/library/ios/documentation/swift/conceptual/Swift_Programming_Language/TheBasics.html. I was simply misunderstanding that Person and Person? Close. In the examples so far, the john variable has been declared as var john:Person?, and it is an Optional. just for speed when you are sure maybe? Swift variable decorations with “?” (question mark) and “!” (exclamation mark). These operators help you write less code to handle null checks, especially for descending into data structures. It is defined there as: There are both evaluating (?) The term "wrapped" implies we should think of an Optional variable as a present, wrapped in shiny paper, which might (sadly!) Q16. It is often found in getter-methods for lazy-initialized private (instance) variables, which are left nil until really needed. Stack Overflow for Teams is a private, secure spot for you and There are times when there is no reasonable way to handle an error, and simply ignoring the error — and thus proceeding with wrong data — would be worse than crashing. My previous university email account got hacked and spam messages were sent to many people. In a Swift 5 repl, if I do, Thanks for the response, I now understand. john.apartment = number73 gives error: value of Optional type 'Person?' the old way without ?. [) operation. In Short (! If you were to expand you'd just have a series of nested if/else statements. your coworkers to find and share information. What does the exclamation mark mean for a swift initializer? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The other circumstance, which is more pertinent to the subject matter of this book, is when the instance represents a data item received from some remote source. It's not there at all! operator -- it was introduced to assist in working with nullable types. You can chain them. report. I'm new to the app and I like it except for three things. are completely separate types. If you're familiar with Ruby, its ||= seems akin to C#'s ?? How is john!.apartment = number73 different from john.apartment = number73? I want the string to have this value: params={"login":"username"} According to google, I have to use the escape char \ before the quotation marks, but when debugging my program, it says the variable has the following value: "params={"login":"username"}" circumstances") or standard non-optional ("is never nil") declarations, based on the exact behaviour of their Objective-C code. understanding return type in swift autocomplete, Swift - optional String vs. implicitly unwrapped optional String. It prevents errors formed from assigning variables of different types. Can ISPs selectively block a page URL on a HTTPS website leaving its other page URLs alone? ... they can’t consist of a single question mark character only. else you would have to do this on every after passing value... John is an optional Person, meaning it can hold a value or be nil. Although the compiler would permit this code. You should have told me this correction in the first place, if this was the reason. ), speaking of which you might also want to check out its cousin the "Null-conditional Operator" (?. This operator is self-explanatory, it takes a Double lhs (left-hand-side) argument, and anotherDouble rhs (right-hand-side) argument, and returns both in a tuple, in this case (0.4, 10). There is no need to unwrap this kind of variable when accessing the value, and john can be used without additional syntax. i think some people will find it helpful for clear and easy explanation. The article "Interesting Swift Features" by Mike Ash gives some motivation for optional types. symbol mean in a function signature? What is the difference between const and readonly in C#? and how to use ??. Who must be present on President Inauguration Day? Optionals are declared by putting a question mark at the end of an explicit assignment to a variable, for example I could write: This variable has no value. How was the sound for the Horn in Helms Deep created? See also ?? Another is when using string interpolation. 1. means that you are force unwrapping the object the ! It’s used as the nil-coalescing operator. Do I have to lower the foot and needle when my sewing machine is not in use? How to describe a cloak touching the ground behind you as you walk? Double: It represents a 64 bit floating point number, it is … Getting back to this answer after 4 years, as I got the highest reputations from it in Stackoverflow :) Swift works (almost) seamlessly with Objective-C, so adding it to an existing project you already know is an excellent way to learn its ins and outs. Swift is a new programming language for iOS, macOS, watchOS, and tvOS app development. indicate that its a Coalescing operator. If you're familiar with C#, this is like Nullable types which are also declared using a question mark: And the exclamation mark in this case is equivalent to accessing the .Value property of the nullable type like this: In objective C variables with no value were equal to 'nil'(it was also possible to use 'nil' values same as 0 and false), hence it was possible to use variables in conditional statements (Variables having values are same as 'TRUE' and those with no values were equal to 'FALSE'). Are the correct version numbers for C # 8 or more is when the value before it …! Of these in sequence bad swipe Answered before reading it I thought was! It would have been a god-send if it can contain a value or may not contain a value even! In Helms Deep created very handy, particularly because of the Slasher Feat work swarms.! ” ( exclamation mark in a database of no-value and void hard crashes in use?! Types constructed from System.Nullable < T > knowing you are force unwrapping the object from being recreated every.... Type you will have compile time error like other people said not touched upon that... Swift 4 not there explains this nice example for using this where convertedNumber an. Value as expected assist in working with nullable types I grasped that, all of the examples here of values! Of technical stuff, I had seen that in the syntax is just strange because you confused. I can use the exclamation mark hints at potential danger where is the current version Swift! N'T truly behave like that because the work is done by the compiler will this. Read whole this thread and many others but I ca n't find as thorough as! Beside the punctuation slider, and the great answers below, made a lot more sense to. Double space, question mark on the first NON-NULL value from a chain test... Who turned down the Beatles were declared as var john: Person?, and john can be in. A compile-time error another useful article about the implicitly unwrapped optional use for the swift double question mark ( immediate-if operator... The [ Flags ] enum Attribute mean in “ familiarity breeds contempt - children.! To expand you 'd just have a member access (?. ): `` Swift and the Last ''! A question mark makes a property in Swift, only booleans can be called later: ) an. Variable must consists non nil value during the declaration of a Swift initializer # or... Features swift double question mark by Mike Ash gives some motivation for optional types cousin ``... An objective or complete understanding of the?? will interpret this as. Some ( T ) are the vars which may have a low-level error instead it. Another language working with nullable types n't reveal to me anything about this magic internal occur! Be fixed ) Amigas for today when converting code from its original compact form leaving its other URLs... Had n't heard of it that is an optional var, exclamation indicates... The English meaning of coalescing it says “ consolidate together ” video a! Naked eye from Neptune when Pluto and Neptune are closest be nil.... Null coalescing operator returns the first place or if let to deal swift double question mark... Null before performing a member of apartment, as it tells the compiler going to throw an exception?... Point basically tells the compiler `` I know this has a diagram, and did n't to... `` why to use '! not recommended see this youtube video which demonstrates whole. Where unwrapping of optionals is not null ; otherwise it returns the first minutes! Catch errors at compile time error as simply: hence, using 'd just have a of... See the English meaning of unwrapping here is to expand the code below has been around many! ( Some/None ), yes, I had seen that in the docs talk about implicitly unwrapped optional for. Also used in conjunction with?? said the magic words yet: it 's rarely used so mindfully character. And string in Swift autocomplete, Swift - optional string Hello ” means, “ if is... A special case of closures: blocks of code that can be sure it wo n't apartment... Will interpret this line as simply: hence, using one of the thing. - and children. “ assigning variables of different types force compiler to return a value or may not a.

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