Objective-C method conflicts with optional requirement method Swift

问题

After the Xcode update, the compiler began to throw an error on the working code (both functions are in the AppDelegate.swift).

func application(application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: NSDictionary?) -> Bool 
{
    FBLoginView.self
    FBProfilePictureView.self
    return true
}

With error:

/Users/../AppDelegate.swift:14:11: Objective-C method 'application:didFinishLaunchingWithOptions:' provided by method 'application(:didFinishLaunchingWithOptions:)' conflicts with optional requirement method 'application(:didFinishLaunchingWithOptions:)' in protocol 'UIApplicationDelegate'

And second

func application(application: UIApplication,        
                            openURL url: NSURL,
                            sourceApplication: NSString?,
                            annotation: AnyObject) -> Bool {
    var wasHandled:Bool = FBAppCall.handleOpenURL(url, sourceApplication: sourceApplication as! String)
    return wasHandled
}

with error

/Users/../AppDelegate.swift:25:11: Objective-C method 'application:openURL:sourceApplication:annotation:' provided by method 'application(:openURL:sourceApplication:annotation:)' conflicts with optional requirement method 'application(:openURL:sourceApplication:annotation:)' in protocol 'UIApplicationDelegate'

I understand that most likely I should like you to stick together somehow these two functions into one. I do not understand why this code suddenly stopped working in 6.3, despite the fact that it worked in 6.2.

回答1:

I'm not sure exactly why the compiler is throwing the error, however I do see a difference in the default Swift version of those same methods. Perhaps you could replace the function declaration with those created with a normal Swift project:

1

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool

2

func application(application: UIApplication, openURL url: NSURL, sourceApplication: String?, annotation: AnyObject) -> Bool

I'd recommend replacing your method declarations with the above to see if it compiles now.

---

EDIT 1 (9/21/2015): I've confirmed these are now up to date for Xcode 7's public release. They removed the optional (annotation: AnyObject?) and made it (annotation: AnyObject), in declaration #2.

回答2:

The type of the launchOptions parameter of the didFinishLaunchingWithOptions function was changed in XCode 6.3:

"launchOptions: NSDictionary?" has become "launchOptions: [NSObject: AnyObject]?"

Just change your function header to match the following:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool

回答3:

You should also make sure you are using the correct type. Use String instead of NSString.

回答4:

Try overriding that method again from Xcode completions. Worked for me.

回答5:

launchOptions have been changed; try changing out "launchOptions: NSDictionary?" to "launchOptions: [NSObject: AnyObject]?"

Hope this helps!

来源：https://stackoverflow.com/questions/28460472/objective-c-method-conflicts-with-optional-requirement-method-swift