Expose swift variadic parameter to Objective-C

Question

I am currently working on a swift dynamic framework which will be used for an objective-c application.

I\'ve created this method (signature):

public          


        

Answer 1

You can bridge variadic functions in C to Swift, but not the other direction. See Using Swift with Cocoa and Objective-C:Interacting with C APIs:Variadic Functions for more on that.

But this isn't that hard to implement by hand. Just create an array version of the method and pass all the variadic forms to it. First in Swift:

public class Test: NSObject {
    convenience public init(buttons: String...) {
        self.init(buttonArray: buttons)
    }

    public init(buttonArray: [String]) {

    }
}

And then expose to ObjC through a category.

@interface Test (ObjC)
- (instancetype) initWithButtons:(NSString *)button, ...;
@end

@implementation Test (ObjC)

- (instancetype) initWithButtons:(NSString *)button, ... {
    NSMutableArray<NSString *> *buttons = [NSMutableArray arrayWithObject:button];
    va_list args;
    va_start(args, button);

    NSString *arg = nil;
    while ((arg = va_arg(args, NSString *))) {
        [buttons addObject:arg];
    }

    va_end(args);
    return [self initWithButtonArray:buttons];
}

@end