Users/raynne/Documents/Development/flutter/.pub-cache/hosted//flutter_inappbrowser-1.2.1/ios/Classes/FlutterWebViewController.swift:53:54: Warning: conditional downcast from 'String?' to 'String' does nothing Users/raynne/Documents/Development/flutter/.pub-cache/hosted//flutter_inappbrowser-1.2.1/ios/Classes/FlutterWebViewController.swift:52:46: The way to reproduce it is changing my deployment target from 8.0 to 11.0.
'/Users/raynne/Documents/Development/flutter/.pub-cache/hosted//flutter_barcode_scanner-0.1.7/ios/Classes/resource.bundle/ic_flash_on.png'Įncountered error while building for device.Īfter searching I saw some people stating that they are able to fixed it by changing their deployment target to 11.0. Rcode_amework/ic_flash_off.png'Ģ) Target 'flutter_barcode_scanner' (project 'Pods') has copy command from '/Users/raynne/Documents/Development/Developments_SourceCode_20191007/kepong/build/ios/Release-iphoneos/flutter_barcode_scanner/flutter_ba '/Users/raynne/Documents/Development/flutter/.pub-cache/hosted//flutter_barcode_scanner-0.1.7/ios/Classes/resource.bundle/ic_flash_off.png'
DOWNCAST ONLY UNWRAPS OPTIONALS CODE
You want to crash the code right here, and start debugging to find out why that optional is nil.Building com.xxxxx for device (ios-release).Īutomatically signing iOS for device deployment using specified development team in Xcode project: N7CVA637YZġ) Target 'flutter_barcode_scanner' (project 'Pods') has copy command from If that optional is nil, something is very wrong. There are times you are absolutely certain there will be a non-nil optional. Also check a class that is optional before using the methods and properties of the class. In order to prevent this, first check an optional for nil, then get its value using the force unwrap operator !ĭo this for anything you make an optional. We cannot unwrap an optional that is nil. If we run now while myNumberOfPizzas is nil, we get a run time error The compiler error message now disappears. Var myNumberOfPizzas:Int = numberOfPizzas! Here we need to use the force unwrap operator ! to get an integer value out of the optional Value of optional type 'Int?' not unwrapped did you mean to use '!' or '?'? Var myNumberOfPizzas:Int = numberOfPizzas If we retrieve a value from numberOfPizzas like this: As I mentioned earlier, optional values have two parts, one for nil and one for the value. However getting data from an optional is slightly more challenging. When declaring optionals, if starting with nil, you can leave off the nil assignment if you wish.Īssigning to an optional is just like assigning to anything else. In Swift any type, not just classes, can be an optional.
However in Objective-C you can’t put a pointer to an integer, only classes. Optionals are a lot like pointers in Objective-C. This would set an integer optional to nil. This would make an optional from the Pizza class. If the optional is nil, there is no value, if the optional is non-nil there is a value. Optionals change any type into a type with a flag for the nil state and a value. There are places where things just don’t exist yet, and we need a way to show it. My choice for a pizza for lunch is not even on my mind. There are many cases where we need a state that says “this does not exist yet.” When I am deciding on breakfast for example I’m thinking about yogurt, coffee and chocolate croissants. I decided to combine what I know about optionals into one post as a reference. That Apple’s documentation peppers information about optionals in two different e-books without consolidating the information doesn’t help. It isn’t hard, just something different to wrap one’s head around. In the first month and a half of using Swift, I could argue the optional value is the most difficult new concept.
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