problems in implementing Gesture Recognizers for iPad app

Discussion in 'iOS Programming' started by newlearner, May 11, 2011.

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  1. newlearner, May 11, 2011

    newlearner macrumors member

    newlearner

    Joined:
    Jul 30, 2009
    Location:
    india
    #1
    hello,

    i am working with gesture recognizers in my app. The app crashes whenever there is any gesture - tap or swipe. here is my code for detecting tap:

    Code:
    
-(void)viewDidLoad{
    UITapGestureRecognizer *recognizer;

    recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapHandler:)];
    recognizer.numberOfTapsRequired=1;

    recognizer.numberOfTouchesRequired=1;
    [self.view addGestureRecognizer:recognizer];
    [recognizer release];
   [super viewDidLoad];
}

- (void) tapHandler: (UITapGestureRecognizer *)gesture {
    NSLog(@"Tap ...");
}
    The app being written is for iPad using iOS 4.3.2

    can anyone point out where the problem is...

    many thanks
     
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  2. jnoxx, May 11, 2011

    jnoxx macrumors 65816

    jnoxx

    Joined:
    Dec 29, 2010
    Location:
    Aartselaar // Antwerp // Belgium
    #2
    not sure, haven't been working with recognizers alot. but u are releasing it, before you're using it. try commenting out the release, and check it out.
     
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  3. newlearner, May 11, 2011

    newlearner thread starter macrumors member

    newlearner

    Joined:
    Jul 30, 2009
    Location:
    india
    #3
    @ jnoxx : tried that too...but it doesnt make any difference
     
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  4. Alphaforcex, May 17, 2011

    Alphaforcex macrumors member

    Joined:
    Jun 23, 2010
    #4
    This is what I did and it works. What's the error?

    Code:
            
//Swipe
        UISwipeGestureRecognizer *swipeLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
        swipeLeft.direction = UISwipeGestureRecognizerDirectionLeft;
        [self.view addGestureRecognizer:swipeLeft];
        [swipeLeft release];

//Tap 
	UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap:)];
 	[self.view addGestureRecognizer:singleTap]; 
        [singleTap release];
     
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  5. Sykte, May 17, 2011

    Sykte macrumors regular

    Joined:
    Aug 26, 2010
    #5
    Actually he isn't, sorry typing on the iPad otherwise I would explain why. You should post any errors you receive this will help other developers help you.
     
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  6. PhoneyDeveloper, May 17, 2011

    PhoneyDeveloper macrumors 68030

    PhoneyDeveloper

    Joined:
    Sep 2, 2008
    #6
    @OP, what does crash mean? What do you see in the debugger console?
     
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  7. newlearner, May 17, 2011

    newlearner thread starter macrumors member

    newlearner

    Joined:
    Jul 30, 2009
    Location:
    india
    #7
    @Alphaforcex: Your code doesnt work for me though. On which OS version are you implementing it?

    @PhoneyDeveloper: The program simply hangs up with an objc_msgSend error. Please find attached the screenshot of the stack trace
     

    Attached Files:

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  8. PhoneyDeveloper, May 18, 2011

    PhoneyDeveloper macrumors 68030

    PhoneyDeveloper

    Joined:
    Sep 2, 2008
    #8
    Crashes in objc_MsgSend are caused by sending a message to a dealloced object. I can't tell why that would happen in your case. The object being messaged is presumably your view controller. Is it possible that the view outlives the view controller? You can turn on NSZombies to debug this further. And you can search the forum and google for objc_MsgSend. It's a very common problem.

    You can start here

    http://www.sealiesoftware.com/blog/...c_explain_So_you_crashed_in_objc_msgSend.html
     
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