Target action is called twice

Question

I have a VC RaceDayChecklistViewController.m which is subclass of RaceDayChecklistViewControllerBase.m.

In RaceDayChecklistVC.m , added a target action which is getting called twice. nextOrNewButton is the button on click of which i want to invoke "demo" action. Also ,checklistnavigationItem is the bar Button item.

- (void)viewDidLoad
{
    checklistTableViewBase=checklistTableView;
   checklistNavigationItemBase=checklistnavigationItem;
    nextOrNewButtonBase=nextOrNewButton;

    [nextOrNewButton addTarget:self action:@selector(demo) forControlEvents:UIControlEventAllEvents];

}

-(void) demo
{
    RaceDayDataController *sharedController = [RaceDayDataController sharedDataController];

    if (sharedController.isSubmited)
    {
        [self.checklistnavigationItem setTitle:@"New"]; //
    }
    else
    {
        [self.checklistnavigationItem setTitle:@"Next"];
        [self showAlert];
    }
}

-(void) viewWillDisappear:(BOOL)animated
{
    [nextOrNewButton removeTarget:self action: @selector(demo) forControlEvents:UIControlEventAllEvents];
}

What could be the reason for multiple call to the action demo? Is it the base class responsible some how?

pls guide.

no its the only place where i used.. @mani – Lalit_vicky Jan 31 '14 at 12:28 — Lalit_vicky, Jan 31 '14 at 12:28

score 6 · Accepted Answer · answered Jan 31 '14 at 12:29

UIButton generates multiple events while pressing: usually they are UIControlEventTouchDownInside and UIControlEventTouchUpInside. So, if you want to handle press, you should catch the one you need (probably UIControlEventTouchUpInside), not UIControlEventsAll.

score 2 · Answer 2 · answered Jan 31 '14 at 12:29

I can see this

[nextOrNewButton removeTarget:self action: @selector(demo) forControlEvents:UIControlEventAllEvents];

That means, When you touch the button,touch up event(UIControlEventTouchUpInside) trigger, so it will fire one time. After that, touch down will happen, so it will fire again with UIControlEventTouchDownInside .

So you can use this,

[nextOrNewButton removeTarget:self action: @selector(demo) forControlEvents:UIControlEventTouchUpInside];

Vijay-Apple-Dev.blogspot.com · Answer 3 · 2014-01-31T12:51:48.343

You are listening about all events, so you are getting all events.

Normally to capture the button tap event we would have UIControlEventTouchUpInside.

Here is the option for you.

        typedef NS_OPTIONS(NSUInteger, UIControlEvents) {
            UIControlEventTouchDown           = 1 <<  0,      // on all touch downs
            UIControlEventTouchDownRepeat     = 1 <<  1,      // on multiple touchdowns (tap count > 1)
            UIControlEventTouchDragInside     = 1 <<  2,
            UIControlEventTouchDragOutside    = 1 <<  3,
            UIControlEventTouchDragEnter      = 1 <<  4,
            UIControlEventTouchDragExit       = 1 <<  5,
            UIControlEventTouchUpInside       = 1 <<  6,
            UIControlEventTouchUpOutside      = 1 <<  7,
            UIControlEventTouchCancel         = 1 <<  8,

            UIControlEventValueChanged        = 1 << 12,     // sliders, etc.

            UIControlEventEditingDidBegin     = 1 << 16,     // UITextField
            UIControlEventEditingChanged      = 1 << 17,
            UIControlEventEditingDidEnd       = 1 << 18,
            UIControlEventEditingDidEndOnExit = 1 << 19,     // 'return key' ending editing

            UIControlEventAllTouchEvents      = 0x00000FFF,  // for touch events
            UIControlEventAllEditingEvents    = 0x000F0000,  // for UITextField
            UIControlEventApplicationReserved = 0x0F000000,  // range available for application use
            UIControlEventSystemReserved      = 0xF0000000,  // range reserved for internal framework use
            UIControlEventAllEvents           = 0xFFFFFFFF
        };

what is most appropriate..Its the first time i am using target..can you pls guide.. i have to just click the button and move.. — Lalit_vicky, Jan 31 '14 at 12:29
@Lalit_vicky You'll probably want to use `UIControlEventTouchUpInside`. — Mick MacCallum, Jan 31 '14 at 12:31
@Lalit_vicky Please you can use http://stackoverflow.com/questions/14856906/touchesbegan-touchesended-touchesmoved-for-moving-uiview — Vijay-Apple-Dev.blogspot.com, Jan 31 '14 at 12:43

score 0 · Answer 4 · answered Jan 31 '14 at 12:41

As you set UIControlEventAllEvents thats why when you touch your button it takes two type of touch so you should use only one type of Event either UIControlEventTouchUpInside or UIControlEventTouchUpOutside.

[nextOrNewButton addTarget:self action:@selector(demo) forControlEvents: UIControlEventTouchUpInside];

Target action is called twice

4 Answers4