Cant get UIButton to highlight with TapGestureRecognizer - iphone

Question

I've setup a tap gesture recognizer and add the recognizer to the uibutton. The button has a background image. When I tap the button it doesn't highlight at all, the only thing I've been able to get it to do is change it's alpha value.
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(singleTapGestureCaptured:)];
singleTap.cancelsTouchesInView = NO;
[btnNext addGestureRecognizer:singleTap];
- (void)singleTapGestureCaptured:(UITapGestureRecognizer *)gesture
{
UIView *tappedView = [gesture.view hitTest:[gesture locationInView:gesture.view] withEvent:nil];
NSLog(#"Touch event view: %#",[tappedView class]);
UIButton *myButton = (UIButton *) tappedView;
[self highlightButton:myButton];
tappedView.alpha = 0.5f;
}
Any would be appreciated. Thanks

Answer 1

You can intercept the touches events with a gesture recognizer, and then programmatically add the recognizer to all your uibuttons. For instance:
//
// HighlighterGestureRecognizer.h
// Copyright 2011 PathwaySP. All rights reserved.
//
#import <Foundation/Foundation.h>
#interface HighlightGestureRecognizer : UIGestureRecognizer {
id *beganButton;
}
#property(nonatomic, assign) id *beganButton;
#end
and the implementation:
//
// HighlightGestureRecognizer.m
// Copyright 2011 PathwaySP. All rights reserved.
//
#import "HighlightGestureRecognizer.h"
#implementation HighlightGestureRecognizer
#synthesize beganButton;
-(id) init{
if (self = [super init])
{
self.cancelsTouchesInView = NO;
}
return self;
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
self.beganButton = [[[event allTouches] anyObject] view];
if ([beganButton isKindOfClass: [UIButton class]]) {
[beganButton setBackgroundImage:[UIImage imageNamed:#"grey_screen"] forState:UIControlStateNormal];
[self performSelector:#selector(resetImage) withObject:nil afterDelay:0.2];
}
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
}
- (void)reset
{
}
- (void)ignoreTouch:(UITouch *)touch forEvent:(UIEvent *)event
{
}
- (BOOL)canBePreventedByGestureRecognizer:(UIGestureRecognizer *)preventingGestureRecognizer
{
return NO;
}
- (BOOL)canPreventGestureRecognizer:(UIGestureRecognizer *)preventedGestureRecognizer
{
return NO;
}
- (void)resetImage
{
[beganButton setBackgroundImage: nil forState:UIControlStateNormal];
}
#end
The way you'd add the gesture recognizer to your button would be like so:
HighlighterGestureRecognizer * tapHighlighter = [[HighlighterGestureRecognizer alloc] init];
[myButton addGestureRecognizer:tapHighlighter];
[tapHighlighter release];
So basically you're declaring it, initializing it, and then adding it. After that, you'll want to release it, since the addGestureRecognizer retains it.
Also simply try
adjustsImageWhenHighlighted = YES set on your buttons? The default is YES, but maybe you changed it in the xib. It's the "Highlighted Adjusts Image" checkbox in the attributes inspector: