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selectorswifttype-safety

Is there a typesafe way to use selectors in Swift?

For the most part, Swift is a huge improvement over Objective-C in terms of type safety. One glaring exception is selectors. In Objective-C, using the expression @selector(notARealSelector:) will give a compiler warning. The Swift equivalent, Selector("notARealSelector:") will always compile but will fail at runtime.

Is there a typesafe way to use selectors in Swift, so I can work with Objective-C APIs that require them?

I have a lot of NSNotification observers in my app and would like to have some kind of compile-time checking that I'm not making typos in my selectors.

Edit: The specific use case is NSNotificationCenter.addObserver.

Solution

  • Typesafe selectors were just released in Xcode 7.3 beta 4:

    let sel = #selector(insertSubview(_:aboveSubview:)) // sel has type

    Selector is now a first class citizen and comes with some nice Swift compiler warnings. If needed you can still pass in a string:

    let sel = Selector("propertyName")

    See a much more complete answer here: @selector() in Swift?

    Xcode Release Notes: http://adcdownload.apple.com/Developer_Tools/Xcode_7.3_beta_4/Xcode_7.3_beta_4_Release_Notes.pdf