Question

I am trying to assign a block to a button object so that each time a button is pressed the block will execute. I have the following defined button subclass that holds the block for each unique button I create.

typedef void (^ButtonPressBlock)();
@interface PhotoButton : UIButton 
{
    ButtonPressBlock photoButtonPressed;
}
@property (copy) ButtonPressBlock photoButtonPressed;
@end

There is a @synthesize photoButtonPressed in the .m

In a separate UIViewController I #import “PhotoButton.h” and then in that view controller I have a method that creates the buttons. The code looks like this.

    PhotoButton* photoButton = [UIButton buttonWithType:UIButtonTypeCustom];
        photoButton.frame = CGRectMake(i, j, thumbSize+2, thumbSize+2);
        [photoButton setImage:photoThumb forState:UIControlStateNormal];
        [photoButton setAdjustsImageWhenHighlighted:NO];

        [photoButton setPhotoButtonPressed:^()
             {                                                    
             [self performSegueWithIdentifier:@"photoSegue" sender:aPhoto];
         }];

assigning the block to the photoButton fails at execution with a

-[UIButton setPhotoButtonPressed:]: unrecognized selector sent to instance…

Not sure what I am doing wrong as blocks are new to me. I thought this would be a great way to make a thumbnail image responsive to a touch and then segue to the full sized image in another view controller. Now I’m not sure.

Answer 1

This:

PhotoButton* photoButton = [UIButton buttonWithType:UIButtonTypeCustom];

should be:

PhotoButton* photoButton = [PhotoButton buttonWithType:UIButtonTypeCustom];

You were creating an instance of UIButton, not PhotoButton