UIButton set touch handler in code

One option is to set the button up using

[myButton addTarget:yourOtherClass action:@selector(mySelector:) forControlEvents:UIControlEventTouchUpInside];

but this is a bit dangerous because target is not retained so you could send the message to a deallocated object.

You could instead set up a protocol

MyController.h

@protocol MyControllerDelegate
- (void)myController:(MyController *)controller buttonTapped:(UIButton *)button;
@end

@interface MyController : UIViewController

@property (nonatomic, assign) id <MyControllerDelegate> delegate;

- (IBAction)buttonTapped:(UIButton *)button;

@end

Then in your implementation

MyController.m

- (IBAction)buttonTapped:(UIButton *)button
{
    if ([self.delegate respondsToSelector:@selector(myController:buttonTapped:)]) {
      [self.delegate myController:self buttonTapped:button];
    }
}

As the method defined in the protocol was not optional I could have instead done a check for (self.delegate) to make sure it is set instead of respondsToSelector.