Stack Overflow
Stack Overflow

Questions tagged [forced-unwrapping]

100 questions
541
votes
23 answers

What does an exclamation mark mean in the Swift language?

The Swift Programming Language guide has the following example: class Person { let name: String init(name: String) { self.name = name } var apartment: Apartment? deinit { println("\(name) is being deinitialized") } } class…
Troy
  • 21,172
  • 20
  • 74
  • 103
40
votes
3 answers

Treating a forced downcast as optional will never produce 'nil'

I've been playing around with Swift and discovered that when down casting an object to be inserted into a dictionary, I get a weird warning: Treating a forced downcast to 'String' as optional will never produce 'nil'. If I replace as with as? then…
Pamelloes
  • 690
  • 1
  • 6
  • 13
29
votes
4 answers

Difference between Force Unwrapping Optionals and Implicitly Unwrapped Optionals

I was very confused about forced unwrapping and implicit unwrapping at first. Now, the following understanding comes from my self-study: There is no action available for implicit unwrapping, but there is something called implicitly unwrapped…
SLN
  • 4,772
  • 2
  • 38
  • 79
8
votes
5 answers

Swift safely unwrapping optinal strings and ints

When I am about to fire my segue for the 2nd view I also send some values like this: if let aTime = ads[indexPath.row]["unix_t"].int { toView.time = aTime } if let aTitle = ads[indexPath.row]["title"].string { toView.title = aTitle } In…
user2636197
  • 3,982
  • 9
  • 48
  • 69
7
votes
1 answer

Is there a way to detect forced unwrapping across a Swift project?

Is there a way (via a compiler flag or a script) to detect forced unwraps across a Swift project? I'm thinking about stuff like these: let b = a as! B let c = a! a!.method() Without triggering false-positives for var a: A! for instance.
ldiqual
  • 15,015
  • 6
  • 52
  • 90
7
votes
1 answer

Scala: Access optional value in optional object

Is there a good way to access a Option Value inside a Option Object? The nested match cases result in a ugly tree structure. So if I have for example: case class MyObject(value: Option[Int]) val optionObject : Option[MyObject] =…
lukaswelte
  • 2,951
  • 1
  • 23
  • 45
5
votes
4 answers

Left side of nil coalescing operator '??' has non-optional type 'String', so the right side is never used

I have a the following code which i am trying to use to initialize a variable and perform some operation on it. let formattedPointsValue: String? self.formattedPointsValue = model.pointUnitsEarned.stringValueWithWhiteSpaceThousandSeperator()+"…
Erent
  • 571
  • 6
  • 15
  • 29
5
votes
1 answer

Why does `+=` not work with implicitly unwrapped optionals

Why does += not work with implicitly unwrapped optionals, for instance: var count: Int! = 10 count = count + 10 // This works count += 10 // this does not work Why isn't the optional implicitly unwrapped, like the case of count = count + 10 ?
Muhammad Zubair Ghori
  • 683
  • 1
  • 6
  • 12
5
votes
2 answers

Purpose of forced unwrapping

In swift documentation, you can find this : if convertedNumber != nil { println("convertedNumber has an integer value of \(convertedNumber!).") } // prints "convertedNumber has an integer value of 123." With this explaination Once you’re sure…
Tancrede Chazallet
  • 7,035
  • 6
  • 41
  • 62
4
votes
1 answer

Default value for optional type 'URL?'

I have an extension allowing me to download images to my UITableView from API. extension UIImageView { func donwloadImage(from url: String) { let urlRequest = URLRequest(url: URL(string: url)!) let task =…
Russ
  • 99
  • 1
  • 7
4
votes
4 answers

Assigning text field value to variable in Swift

I am trying to learn Swift and it is turning out to be more different from other languages than I expected... I just want to store the value of a user's input as an integer in a variable. My attempts result in the following error: "fatal error:…
Darth Washington
  • 43
  • 1
  • 4
4
votes
1 answer

Why does SwiftyJSON create implicitly unwrapped optional for its constants?

In SwiftlyJSON's code, it defines the following constants using forced unwrapping: ///Error code public let ErrorUnsupportedType: Int! = 999 public let ErrorIndexOutOfBounds: Int! = 900 public let ErrorWrongType: Int! = 901 public let ErrorNotExist:…
Boon
  • 40,656
  • 60
  • 209
  • 315
4
votes
1 answer

Early return/golden path in Swift

I'm used to write code with early return/golden path in Objective-C. I tried this approach in Swift, and noticed that early return comes at the expense of using the forced unwrapping operator (!) when optionals are involved. Take a method that…
hpique
  • 119,096
  • 131
  • 338
  • 476
3
votes
2 answers

Need help understanding interaction between convenience initializer and instance variable unwrapping in Swift

I'm pouring over the Swift documentation about initializers and unwrapping and I'm failing to grok something fundamental about the way this works. Goal: I'd like to subclass SKShapeNode and use let reverse : Bool to define an instance variable that…
thebossman
  • 4,598
  • 11
  • 34
  • 45
3
votes
1 answer

Swift4: Forced cast from 'Data?' to 'Data' only unwraps optionals; did you meant to use '!'?

at the last update to Swift 4, im always getting the same error at the same spot and i don't know how to clear it... if tried to use ! instead of ? but the error keep going in the opposite direction. the Error is with both Date? and Data? thats the…
Sjero Markus
  • 111
  • 8
1
2 3 4 5 6 7