Passing Around a Selector and Then Specifying Parameters

Question

I have a function that creates a UIView with a bunch of UIButtons.

Each button calls a function with a string for a parameter.

So, in my function I do something like:

[button addTarget: [multiRadio objectAtIndex:0]
           action: NSSelectorFromString([multiRadio objectAtIndex:1])
 forControlEvents:UIControlEventTouchUpInside];

However, this bit of code doesn't specify the string parameter that the action needs to get passed.

If I have that string parameter in [multiRadio objectAtIndex:2], how do I set the button's actions to use the string?

Answer 1

Why not just access it directly from the method you call? Instead of this:

- ( void )someMethod:( id )sender withString:( NSString * )string {
    [ self doSomethingWithString:string ];
}

use this:

- ( void )someMethod:( id )sender {
    SomeClass *multiRadio = [[ SomeClass alloc ] init ];
    [ self doSomethingWithString:[ multiRadio objectAtIndex:2 ]];
    ...
    [ multiRadio release ];
}

Change the method signatures as necessary, obviously, but that’s one way around it.

Answer 2

I'd create an object class to act as the receiver for these events. Something like this:

ActionWrangler *wrangler = [[ActionWrangler alloc] init];
wrangler.target = [multiRadio objectAtIndex:0];
wrangler.selector = NSSelectorFromString([multiRadio objectAtIndex:1]);
wrangler.argument = [multiRadio objectAtIndex:2];
[button addTarget:wrangler
           action:@selector(wrangle)
 forControlEvents:UIControlEventTouchUpInside];

And then ActionWranger would have a wrangle method like so:

- (void)wrangle
{
    [target performSelector:selector withObject:argument];
}

Your biggest issue then would be tracking the ActionWrangler instances so you can release them.