UILongPressGestureRecognizer not working for all UIButtons - ios

Question

I'm having a problem that I fear has a simple solution. Each time the 'createNewSetInDB:' method is called, a new UIButton* is created, assigned a target for when the user presses the button, and assigned a UILongPressGesture* for when a user long presses the button.
The 'openSet:' method is correctly being called when a user taps one of these buttons. The 'showHandles:' long press method is only being called for the LAST UIButton* that was created. So if the 'createNewSetInDB:' method gets called 4 times and therefore creates 4 UIButtons, the first three do not handle the UILongPressGesture. The 4th UIButton does.
Any ideas?
UILongPressGestureRecognizer *showHandlesLongPress;
- (void)viewDidLoad
{
showHandlesLongPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(showHandles:)];
showHandlesLongPress.minimumPressDuration = .5;
}
- (void)createNewSetInDB:(BOOL)doWeAddItToTheDatabase
{
UIButton *newSet = [[UIButton alloc]initWithFrame:
CGRectMake((sliderMusic.frame.origin.x + imgWhiteLine.frame.size.width / 2) + (_musicPlayer.currentPlaybackTime * 10),
6,
35,
25)];
[newSet addTarget:self action:#selector(openSet:) forControlEvents:UIControlEventTouchUpInside];
[newSet setTitleColor:[MobileMarcherVariables sharedVariableInstance].systemColor forState:UIControlStateNormal];
[newSet.layer setBorderColor:[[MobileMarcherVariables sharedVariableInstance].systemColor CGColor]];
[newSet.layer setBorderWidth:1];
[newSet.titleLabel setFont:[UIFont systemFontOfSize:15]];
[newSet setTitle:[NSString stringWithFormat:#"%i",totalNumberOfSets] forState:UIControlStateNormal];
[scrollviewMusic addSubview:newSet];
[arrayofSetButtons addObject:newSet];
[newSet addGestureRecognizer:showHandlesLongPress];
if (doWeAddItToTheDatabase) [[NSNotificationCenter defaultCenter] postNotification:newSetNotification];
}
- (void)showHandles:(UILongPressGestureRecognizer*)gesture
{
if (gesture.state == UIGestureRecognizerStateBegan)
{
NSLog(#"long press");
for (UIButton *but in arrayofSetButtons)
{
if (but.tag != gesture.view.tag)
{
but.alpha = .5;
}
}
[scrollviewMusic bringSubviewToFront:lefthandle];
[scrollviewMusic bringSubviewToFront:righthandle];
lefthandle.hidden = NO;
righthandle.hidden = NO;
lefthandle.frame = CGRectMake(gesture.view.frame.origin.x - 1,
gesture.view.frame.origin.y - gesture.view.frame.size.height,
2, 50);
righthandle.frame = CGRectMake((gesture.view.frame.origin.x - 1) + gesture.view.frame.size.width,
gesture.view.frame.origin.y - gesture.view.frame.size.height,
2, 50);
}
}

Answer 1

You have to assign one UILongPressGestureRecognizer per UIButton. They can all point to the same method.
- (void)createNewSetInDB:(BOOL)doWeAddItToTheDatabase
{
UIButton *newSet = [[UIButton alloc]initWithFrame:
CGRectMake((sliderMusic.frame.origin.x + imgWhiteLine.frame.size.width / 2) + (_musicPlayer.currentPlaybackTime * 10),
6,
35,
25)];
[newSet addTarget:self action:#selector(openSet:) forControlEvents:UIControlEventTouchUpInside];
[newSet setTitleColor:[MobileMarcherVariables sharedVariableInstance].systemColor forState:UIControlStateNormal];
[newSet.layer setBorderColor:[[MobileMarcherVariables sharedVariableInstance].systemColor CGColor]];
[newSet.layer setBorderWidth:1];
[newSet.titleLabel setFont:[UIFont systemFontOfSize:15]];
[newSet setTitle:[NSString stringWithFormat:#"%i",totalNumberOfSets] forState:UIControlStateNormal];
[scrollviewMusic addSubview:newSet];
[arrayofSetButtons addObject:newSet];
// Add gesture recognizer
//
UILongPressGestureRecognizer *showHandlesLongPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(showHandles:)];
showHandlesLongPress.minimumPressDuration = .5;
[newSet addGestureRecognizer:showHandlesLongPress];
if (doWeAddItToTheDatabase) [[NSNotificationCenter defaultCenter] postNotification:newSetNotification];
}

Answer 2

A gesture recognizer can only be attached to one view at a time. You're only creating one gesture recognizer. Each time you create a button, you attach the existing gesture recognizer to the new button, which removes it from the prior button.
Create a new gesture recognizer for each new button.
- (void)createNewSetInDB:(BOOL)doWeAddItToTheDatabase
{
UIButton *newSet = [[UIButton alloc]initWithFrame:
CGRectMake((sliderMusic.frame.origin.x + imgWhiteLine.frame.size.width / 2) + (_musicPlayer.currentPlaybackTime * 10),
6,
35,
25)];
[newSet addTarget:self action:#selector(openSet:) forControlEvents:UIControlEventTouchUpInside];
[newSet setTitleColor:[MobileMarcherVariables sharedVariableInstance].systemColor forState:UIControlStateNormal];
[newSet.layer setBorderColor:[[MobileMarcherVariables sharedVariableInstance].systemColor CGColor]];
[newSet.layer setBorderWidth:1];
[newSet.titleLabel setFont:[UIFont systemFontOfSize:15]];
[newSet setTitle:[NSString stringWithFormat:#"%i",totalNumberOfSets] forState:UIControlStateNormal];
[scrollviewMusic addSubview:newSet];
[arrayofSetButtons addObject:newSet];
UILongPressGestureRecognizer *showHandlesLongPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(showHandles:)];
showHandlesLongPress.minimumPressDuration = .5;
[newSet addGestureRecognizer:showHandlesLongPress];
if (doWeAddItToTheDatabase) [[NSNotificationCenter defaultCenter] postNotification:newSetNotification];
}