Question

I currently use objc_msgSend to invoke such selector on collection of object. Is there any better way to do that? Here is my code:

@protocol ADelegateProtocol {
   -(void) timeToEventOneDidChange:(NSInterval) event1;
   -(void) timeToEventTwoDidChange:(NSInterval) event1;
}

- (void) delegatesPerformSelector:(SEL) selector withTimeIntervalAsFristParameter:(NSTimeinterval) timeInterval {
    for (id<ADelegateProtocol> delegate in delegates) {
        if([delegate respondsToSelector:selector]) {
            objc_msgSend(delegate, selector, timeInterval);
        }
    }
}

The selector is passed in as a parameter, timeInterval is a non-object value.

Note: I don’t want to use KVO.

Answer 1

If you are going to use objc_msgSend() you must create a correctly typecast function pointer to do so. Relying on varargs to map to non-varargs doesn’t work in all cases.

I.e. You’d want:

void (*myMessage)(id, SEL, NSTimeInterval) = objc_msgSend;
myMessage(delegate, aSelector, aTimeInterval);

(typed into SO — consider the syntax an approximation. 🙂