Question

I would like to put the undocumented trash can animation in my program. The call
method is:

+ (void)animateToolbarItemIndex:(unsigned)index duration:(double)duration target:(id)target didFinishSelector:(SEL)selector;

Can anyone figure out what I should plug in for:

• index
• duration
• target
• selector
  ?

My trials are not working resulting in the error:

2011-11-15 16:05:20.639 CNiPhone[973:707] +[UIToolbar animateToolbarItemIndex:duration:target:didFinishSelector:]: unrecognized selector sent to class 0x3f019c08
2011-11-15 16:05:20.641 CNiPhone[973:707] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[UIToolbar animateToolbarItemIndex:duration:target:didFinishSelector:]: unrecognized selector sent to class 0x3f019c08'

Here is the relevant code:

@interface UIToolbar (privateMethods2)

+ (void)animateToolbarItemIndex:(unsigned)index duration:(double)duration target:(id)target didFinishSelector:(SEL)selector;

@end

    [UIToolbar animateToolbarItemIndex:0 duration:0.5 target:trashToolbarButton didFinishSelector:@selector(animateTrashStep2)];
    [UIToolbar commitAnimations];

- (void) animateTrashStep2 {
}

Answer 1

You dont need to do any undocumented stuff for this, just create a custom UIButton. Download the UIKit Artwork Extractor and you’ll find the frames for the trash can animation, as well as the UIBarButtonItem background.