UITextView touch events not firing

问题

I have a UITextView that I want to detect a single tap for.

It looks like I would be fine with simply overriding touchesEnded:withEvent and checking [[touches anyObject] tapCount] == 1 , however this event doesn't even fire.

If I override the 4 events like this:

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    NSLog(@"touchesBegan (tapCount:%d)", touch.tapCount);
    [super touchesBegan:touches withEvent:event];
}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
        NSLog(@"touches moved");
}

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    NSLog(@"touchesEnded (tapCount:%d)", touch.tapCount);
        [super touchesEnded:touches withEvent:event];
}

-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
        NSLog(@"touches cancelled");
}

I get output like this:

> touchesBegan (tapCount:1)
> touchesCancelled 
> touchesBegan (tapCount:1) 
> touches moved 
> touches moved
> touches moved 
> touchesCancelled

It seems I never get the touchesEnded event.

Any ideas?

回答1:

I subclassed UITextview like so, which seems to work, even with IOS 5.0.1. The key is to override touchesBegan as well, not just touchesEnded (which is what I'm really interested in).

@implementation MyTextView


- (id)initWithFrame:(CGRect)frame {
    return [super initWithFrame:frame];
}

- (void) touchesBegan: (NSSet *) touches withEvent: (UIEvent *) event { 
    // If not dragging, send event to next responder
    if (!self.dragging) 
        [self.nextResponder touchesBegan: touches withEvent:event]; 
    else
        [super touchesBegan: touches withEvent: event];
}

- (void) touchesEnded: (NSSet *) touches withEvent: (UIEvent *) event { 
    // If not dragging, send event to next responder
    if (!self.dragging) 
        [self.nextResponder touchesEnded: touches withEvent:event]; 
    else
        [super touchesEnded: touches withEvent: event];
}

- (BOOL)canPerformAction:(SEL)action withSender:(id)sender {
    if (action == @selector(paste:))
        return NO;
    if (action == @selector(copy:))
        return NO;
    if (action == @selector(cut:))
        return NO;
    if (action == @selector(select:))
        return NO;
    if (action == @selector(selectAll:))
        return NO;
    return [super canPerformAction:action withSender:sender];
}

- (BOOL)canBecomeFirstResponder {
    return NO;
}

- (void)dealloc {
    [super dealloc];
}

回答2:

Update: I ended up using the technique here: https://devforums.apple.com/message/94569#94569

I'm not sure if this is a bug or not, but the UITextView does need to utilize the touch events to do the popup menu for copy & paste for 3.0, so that might explain why it swallows this event.

Pretty lame if you ask me.

Update: I blogged about this here: http://benscheirman.com/2009/07/detecting-a-tap-on-a-uitextview

回答3:

You can turn off Cut/Copy/Paste by overriding the canPerformAction:withSender: method, so you could just return NO for all the actions you don't want to permit.

See the UIResponder documentation...

Hopefully that will stop your touches from being eaten.

来源：https://stackoverflow.com/questions/1096069/uitextview-touch-events-not-firing

标签

iphone

iphone-sdk-3.0

uitextview