从Single View Application（objective-c）以函数作为Cocoa Touch Framework（swift）的参数的调用方法

Question

I created Cocoa Touch Framework in swift (called MyFramework). In MyFramework I have method which requires functions as arguments. In short hand MyFramework contains this code:

public class MyFramework : NSObject {
    public func MyMethod(successCallback : (String) -> Void, errorCallback : (String, String) -> Void) -> Void {
        dispatch_async(dispatch_get_main_queue(), { () -> Void in
            // successCallback("some value");
            // errorCallback("error reason", "error message");
        });
    }
}

I can include MyFramework in Single View Application called MyAppSwift (in swift ) and successfully call MyMethod of MyFramework in ViewController.swift by this code:

class ViewController: UIViewController {
    let myframework : MyFramework = MyFramework();

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        myframework.MyMethod(self.onSuccess, errorCallback : self.onError);
    }

    private func onSuccess(value : String) {
        // ... 
    }

    private func onError(reason : String, error : String) {
        // ...
    }
}

I can include MyFramework in Single View Application called MyAppObjectiveC (in objective-c) but I do not know how to call MyMethod of MyFramework in ViewController.m ...

// In ViewController.h

#import <UIKit/UIKit.h>
#import <MyFramework/MyFramework.h>
@interface ViewController : UIViewController {

}
@property (strong, nonatomic) MyFramework * myframework;
- (void) onSuccess : (NSString *) value;
- (void) onError : (NSString *) reason : (NSString *) error;
@end

.

// In ViewController.m

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void) viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    self.myframework = [[MyFramework alloc] init];
    [self.myframework MyMethod : self onSuccess, self onError];
}
- (void) onSuccess : (NSString *) value {
    // ...
}
- (void) onError : (NSString *) reason : (NSString *) error {
    // ...
}

@end

This line [self.myframework MyMethod : self onSuccess, self onError]; is not working. Xcode says expecting identifier ":" after onSuccess and then expects expresion. Im not sure what to insert. I read several answers on stackoverflow how to pass method as argument in objective-c but no success. For example I have tried selectors [self.myframework MyMethod : @selector(onSuccess:), @selector(onError::)]; but Xcode says: "Sending 'SEL' to parameter of incompatible type 'void(^_Nonnull)(NSString * _Nonnull __strong)'

Answer 1

As you pointed out, according to the *-Swift.h header Swift's MyMethod is imported into Objective-C as taking blocks as arguments. So, you need to pass it blocks that wrap the Objective-C method calls, something like this:

[self.myframework MyMethod: ^ (NSString * s){ [self onSuccess:s]; }
       errorCallback: ^(NSString * s1, NSString * s2) { [self onError:s1:s2]; }];

See here for more info about Objective-C blocks: https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/ProgrammingWithObjectiveC/WorkingwithBlocks/WorkingwithBlocks.html