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.

Answer 1

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.

Answer 2

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];