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Ios swift – Cannot Extend UIApplication to Conform to Custom Protocol in Xcode 16

I am trying to extend UIApplication to conform to a custom protocol AppSwitcher for handling URL opening. This code worked fine in Xcode 15, but after upgrading to Xcode 16, it is causing errors.

public protocol AppSwitcher {
    func open(
        _ url: URL,
        options: [UIApplication.OpenExternalURLOptionsKey: Any],
        completionHandler completion: ((Bool) -> Void)?
    )
}

extension UIApplication: AppSwitcher {}

enter image description here

n Xcode 16, I can no longer extend UIApplication to conform to my AppSwitcher protocol without encountering errors. It worked perfectly in Xcode 15.

  • Has anyone else experienced this in Xcode 16?
  • Is this a change in Swift 5.9 or the iOS SDK?
  • What’s the reason behind this change, and are there any workarounds to achieve the same result?
Tags:

2

Answers


  1. 0

    This is a change in the iOS SDK. The open method now has more annotations on its completion handler – @MainActor and @Sendable.

    You should add those to your protocol method too.

    public protocol AppSwitcher {
    @MainActor
    func open(
        _ url: URL,
        options: [UIApplication.OpenExternalURLOptionsKey: Any],
        completionHandler completion: (@MainActor @Sendable (Bool) -> Void)?
    )
}

    Also consider using the async version of the open method in your protocol.

    public protocol AppSwitcher {
    @MainActor
    func open(_ url: URL, options: [UIApplication.OpenExternalURLOptionsKey : Any]) async -> Bool
}

    If this change breaks some other parts of your code, that means you were not using open in a concurrency-safe way in the first place.

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  2. 0

    FYI if you want to compile code in Xcode15 after updating on

    func open(
    _ url: URL,
    options: [UIApplication.OpenExternalURLOptionsKey: Any],
    completionHandler completion: (@MainActor @Sendable (Bool) -> Void)?
)

    you can use #if compiler(>=x.x.x)

    for xcode 15.1 compiler is 5.9.2

    /Applications/Xcode
    15.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift
    –version swift-driver version: 1.87.3 Apple Swift version 5.9.2 (swiftlang-5.9.2.2.56 clang-1500.1.0.2.5) Target:
    arm64-apple-macosx14.0

    for xcode 16.1 compiler is 6.0.2

    /Applications/Xcode
    16.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift
    –version swift-driver version: 1.115 Apple Swift version 6.0.2 (swiftlang-6.0.2.1.2 clang-1600.0.26.4)

    #if compiler(>=6.0.0)
func open(
    _ url: URL,
    options: [UIApplication.OpenExternalURLOptionsKey: Any],
    completionHandler completion: (@MainActor @Sendable (Bool) -> Void)?
)
#else
func open(
    _ url: URL,
    options: [UIApplication.OpenExternalURLOptionsKey: Any],
    completionHandler: ((Bool) -> Void)?
)
#endif
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