UIApplicationDelegate extension in Swift

Question

Created Jul ’16

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I have an iOS app written in Objective-C and I want to add an extension for UIApplicationDelegate using Swift. Specifically, I want to add code for the Objective-C method:

- (BOOL)application:(UIApplication *)app openURL:(NSURL *)url options:(NSDictionary<NSString *,id> *)options;

so that my app can handle an imported file.

In Swift, this method has the signature:

optional func application(_ app: UIApplication, open url: URL, options: [String : AnyObject] = [:]) -> Bool

To simplify the problem and I have created a Single View Application and have added the Swift code:

import Foundation
extension AppDelegate {
     @objc public func application(_ app: UIApplication, open url: URL, options: [String : AnyObject] = [:]) -> Bool {
   
        return true
    }

    @objc public func testMessage() {
        print("Test Message")
    }
}

This code compiles and runs, but does not get called which a file is imported. The MODULE-NAME-swift.h file conatins the following code:

...
@class UIApplication;


@interface AppDelegate (SWIFT_EXTENSION(AppDelegateTest))
- (BOOL)application:(UIApplication * _Nonnull)app open:(NSURL * _Nonnull)url options:(NSDictionary<NSString *, id> * _Nonnull)options;
- (void)testMessage;
@end
...

This does not have the expected Objective-C signature and therefore, I assume is not called when a file is imported. Note that I can call both of these methods from Objective-C code,

If I change the signature in the Swift code to:

    @objc public func application(_ app: UIApplication, openURL url: URL, options: [String : AnyObject] = [:]) -> Bool {
     
        return true
    }

I get a compilation error:

Delegate.swift:13:24: Method 'application(_:openURL:options:)' with Objective-C selector 'application:openURL:options:' conflicts with method 'application(_:open:options:)' with the same Objective-C selector
__ObjC.AppDelegate:20:17: Method 'application(_:open:options:)' declared here

Any help would be appreciated.

David

Boost

Answer 1

KMT OP

Jul ’16

Confirm the Swift versions in play and see:

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

0

Answer 2

formal OP

Jul ’16

I have made a simpler example.

First I defined the following Objective-C protocol and changed AppDelegate to adopt it:

@protocol XXXX
@optional
-(void)printMe:(NSString* _Nullable) text;
@end

@interface AppDelegate : UIResponder <UIApplicationDelegate,XXXX>
@property (strong, nonatomic) UIWindow *window;
@end

I then added the function printMe1 to the extension for AppDelegate:

extension AppDelegate {
  
    @objc public func printMe1(_ text: String?) {
        print(text)
    }
}

This compiles and the resulting MODULE-NAME-swift.h files contains the following code:

@interface AppDelegate (SWIFT_EXTENSION(AppDelegateTes
- (void)printMe1:(NSString * _Nullable)text;
@end

The generated signature for printMe1 "matches" that of printMe in the protocol definition.

If I change printMe1 to printMe I get the following compilation errors:

AppDelegate.swift:29:23: Method 'printMe' with Objective-C selector 'printMe:' conflicts with previous declaration with the same Objective-C selector
__ObjC.AppDelegate:99:17: 'printMe' previously declared here

I would have expected the two declarations of printMe in Objective-C to match?

David

0

Answer 3

OOPer OP

Jul ’16

Your issue can be easily reproduced, and I can find exactly the same message.

Try modifying the Objective-C header for `AppDelegate` as:

@interface AppDelegate : UIResponder <UIApplicationDelegate>

(Just removing `,XXXX`)

and the extension in Swift:

extension AppDelegate: XXXX {

(Moving the conformance declaration for `XXXX' the the extension.)

and then, see what you get.

I'm not sure whether this is a current limitation of Swift that we need to accept for a while, or it's a sort of bug which should be fixed soon.

0

Answer 4

lui OP

Dec ’16

Hello, I'm having the exact same issue here, did you find the way to solve it?

Thank you in advance

0