Iphone – Detect if certain UIView was touched amongst other UIViews

iphoneuitouchuiview

I have 3 UIViews, layered on top of one large uiview. I want to know if the user touches the top one and not care about the other ones. I will have a couple of buttons in the second UIView and a UITable in the 3rd UIView.

Problem is I turn userInteractionEngabled on on the first view and that works, but all the other views respond in the same way even if I turn it off. If I disable userInteractionEnabled on self.view none of them respond. I also can't detect which view was touched in the touchesBegan delegate method.

My code:

UIView *aView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 150)];
aView = userInteractionEnabled = YES;
[self.view addSubview:aView];

UIView *bView = [[UIView alloc] initWithFrame:CGRectMake(0, 150, 320, 50)];
bView.userInteractionEnabled = NO;
[self.view addSubview:bView];

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
//This gets called for a touch anywhere
}

Best Answer

In order to check whether certain view inside another view was touched you can use hitTest.

- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event;

In your custom implementation of touchesBegan check every touch in touches set. The point for hitTest method can be obtained using

- (CGPoint)locationInView:(UIView *)view;

method, where the view is your superView (the one that contains other views).

EDIT: Here's a fast custom implementation:

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { 
    CGPoint locationPoint = [[touches anyObject] locationInView:self];
    UIView* viewYouWishToObtain = [self hitTest:locationPoint withEvent:event];
}

I hope this was helpful, Paul

Related Solutions

R – change counterclockwise to clockwise with CGAffineTransformIdentity

I'm not sure what the state is when touchesEnded (in terms of rotation) and I'm assuing you chose degreesToRadians(-130) to try and do it partially and expect the next method to do the rest. This should be a better solution that hopefully yields the result you're expecting. I'm not sure what cadran is or why you're rotating that, so I'll just rotate the wheel.

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    [UIView setAnimationBeginsFromCurrentState:YES];
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.2];
    wheel.transform = CGAffineTransformMakeRotation(degreesToRadians(-130));
    // I would recommend that the degrees you rotate be half of whatever your rotation is.
    // this would make the wheel rotate to the home position more evenly
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:@selector(animatewheelViewToCenter:finished:context:)];
    [UIView commitAnimations];
}

- (void)animatewheelViewToCenter:(NSString *)animationID finished:(NSNumber *)finished context:(id)context {
    [UIView setAnimationBeginsFromCurrentState:YES]; // you might need to make this NO
    [UIView beginAnimations:nil context:NULL];
    [UIViewsetAnimationDuration:0.2];
    wheel.transform = CGAffineTransformIdentity;
    [UIView commitAnimations];
}

EDIT: Actually, I would probably make the rotation (in the example -130 degrees) slightly more than what half would be, because CGAffineTransformIdentity is gonna take the shortest path to go back to regular, so if you go exactly 1/2 way, it may not go the correct direction (clockwise or counter-clockwise) that you want.

Objective-c – detect if higher subview has been touched

If I understand correctly, the touchesEnded event is detected, but not by the subview that needs to know about it. I think this might work for you:

In a common file, define TOUCHES_ENDED_IN_SUPERVIEW as @"touches ended in superview".

In the touchesEnded method of the containing view that is firing, add

[[NSNotificationCenter defaultCenter] postNotificationName:  TOUCHES_ENDED_IN_SUPERVIEW object: self];

In the touchesBegan of the subviews, add

[[NSNotificationCenter defaultCenter] addObserver: self 
    selector: @selector(touchesEnded:) 
    name: TOUCHES_ENDED_IN_SUPERVIEW 
    object: self.superview];

In the touchesEnded methods of the subviews, use your normal logic for the event, and also add

[[NSNotificationCenter defaultCenter] removeObserver: self name: TOUCHES_ENDED_IN_SUPERVIEW object: self.superview];

Remember to put [[NSNotificationCenter defaultCenter] removeObserver: self] in your dealloc as well, in case it is possible to leave the page without getting the touchesEnded event.

You might want the notification to send its message to a special touchesEndedInSuperview method, which would invoke touchesEnded itself, but that depends on whether you have any special processing to do in that case.

Best Answer

Related Solutions

R – change counterclockwise to clockwise with CGAffineTransformIdentity

Objective-c – detect if higher subview has been touched

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