Message Sent To Deallocated Instance on UIButton inside iCarousel - ios

Question

I have implemented iCarousel (https://github.com/nicklockwood/iCarousel) into my Xcode project and now have a scrolling carousel of views. Inside each view I have a UIButton, which I have added a UILongPressGestureRecogniser to, like this:
UILongPressGestureRecognizer *lpgr = [[UILongPressGestureRecognizer alloc] init];
[lpgr setMinimumPressDuration:1.5];
[lpgr addTarget:self action:#selector(testAction)];
[self.demoButton addGestureRecognizer:lpgr];
However, when I tap for 1.5 seconds, the following error is displayed in the console:
2014-07-01 09:50:08.002 ExampleApp[3117:892602] -[ExampleVC testAction]: message sent to deallocated instance 0x15cd7bd20
(lldb)*
I haven't seen any section of the code which is releasing the views, so very confused. Why is this and how can I fix it?

Answer 1

I think there can be a problem like this:
UILongPressGestureRecognizer *lpgr = [[UILongPressGestureRecognizer alloc] init];
[lpgr setMinimumPressDuration:1.5];
[lpgr addTarget:self action:#selector(testAction)];
[self.demoButton addGestureRecognizer:lpgr];
You forgot to release lpgr after these lines.
[lpgr release];
And if you miss this line, and demo button is released by iCarussel because of memory optimization, your gestureRecognizer won't be released and will send a message to the deallocated demoButton.
And use the LongPress like this:
[[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(handleLongPress:)];
and handle:
- (void)handleLongPress:(UILongPressGestureRecognizer *)gesture{
if (gesture.state == UIGestureRecognizerStateEnded) {
//Do Whatever You want on End of Gesture
}
else if (gesture.state == UIGestureRecognizerStateBegan){
//Do Whatever You want on Began of Gesture
}
}
and don't forget to implement <UIGestureRecognizerDelegate>
Update:
Inside each view I have a UIButton
You have a button inside each view, but about your code I see that you have a class variable demobutton. So when you initialize a view add your demo button like this:
UIView* yourView ...
UIButton* demoButton = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, 100, 100)];
[yourView addSubview:demoButton];
UILongPressGestureRecognizer *lpgr = [[UILongPressGestureRecognizer alloc] init];
[lpgr setMinimumPressDuration:1.5];
[lpgr addTarget:self action:#selector(testAction:)];
[demoButton addGestureRecognizer:lpgr];
[demoButton release];
[lpgr release];