How can I add arguments to a selector passed as a parameter in ObjectiveC

Question

I'm trying to write a method in Objective C which takes a @selector as a parameter. It works fine - provided that I don't want the selector itself to have parameters (and I do).

- (void) testWithInput:(NSString*) testString1 andInput:(NSString*)testString2 {
    NSLog(@"%@ %@", testString1, testString2);
}

- (void)executeSelector:(SEL)func fromObject:(id)object {
    [object performSelector:func];
}

- (void)runSelector {
    NSString* string1 = @"Hello ";
    NSString* string2 = @"World";
    [self executeSelector:@selector(testWithInput:andInput:) fromObject:self];
}

But how, in the runSelector function can I specify that string1 and string2 need to be passed in as arguments for the selector?

I suppose that I could pass in the parameters as a separate set of arguments to execute selector - but that feels quite messy. Is there a neater way?

I've done a bit of research, on StackOverflow (and elsewhere) - but either the answer isn't quite right or I can't understand it fully.

How to I pass @selector as a parameter?

How can I pass a parameter to a selector?

Objective-C: Calling selectors with multiple arguments

In fact, I'm comfortable passing parameters to selectors normally - it's when the selector is itself a parameter that I have a problem.

Answer 1

You need to add parameters for the arguments. Your contrived example will work with the following changes:

- (void) testWithInput:(NSString*) testString1 andInput:(NSString*)testString2 {
    NSLog(@"%@ %@", testString1, testString2);
}

- (void)executeSelector:(SEL)func fromObject:(id)object withString1:(NSString *)string1 andString2:(NSString *)string2 {
    // This doesn't scale. Two arguments is as far as you can go using `performSelector`.
    [object performSelector:func withObject:string1 withObject:string2];
}

- (void)runSelector {
    NSString* string1 = @"Hello ";
    NSString* string2 = @"World";
    [self executeSelector:@selector(testWithInput:andInput:) fromObject:self withString1:string1 andString2:string2];
}

Since it's unclear what you are actually trying to accomplish it is difficult to offer any further advice on a better solution other than to suggest using blocks is likely a better choice.