UIButton inside UIImageView does not respond to taps - ios

Question

I have a scroll view, which has an image view with an image as a subview, and the image view has a UIButton as one of its subviews. The problem is, I am not able to click on the button. I can SEE the button, but I cannot tap on it.
Can someone tell me what is it that I am messing up? Any help is greatly appreciated! Thanks!
Below is the code:
scrollView = [[UIScrollView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"img.jpg"]];
scrollView.delegate = self;
self.view = scrollView;
// add invisible buttons
[self addInvisibleButtons];
[scrollView addSubview:imageView];
addInvisibleButtons has the following code:
UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[button addTarget:self action:#selector(buttonHandler) forControlEvents:UIControlEventAllEvents];
[button setTitle:#"point" forState:UIControlStateNormal];
button.frame = CGRectMake(0.0, 0.0, 40.0, 40.0);
[self.imageView addSubview:button];

Answer 1

UIImageView has userInteractionEnabled set to NO/ false by default.
You are adding the button as a subview to the image view. You should set it to YES / true.

Answer 2

May I ask why are you adding invisible UIButtons to UIImageView?
Seems like a bad practice, notice Interface Builder doesn't allow you to add UIButton inside them.
If you want an image with touch handling, you can:
UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];
[button addTarget:self action:#selector(buttonHandler) forControlEvents:UIControlEventAllEvents];
[button setTitle:#"point" forState:UIControlStateNormal];
[button setImage:[UIImage imageNamed:#"img.jpg"] forState:UIControlStateNormal];
[button setFrame:CGRectMake(0.0, 0.0, 40.0, 40.0)];
[scrollView addSubview:button];

Answer 3

You can have addInvisibleButtons implementation as
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button setBackgroundColor:[UIColor clearColor]];
[button addTarget:self action:#selector(buttonHandler) forControlEvents:UIControlEventAllEvents];
[button setTitle:#"point" forState:UIControlStateNormal];
button.frame = CGRectMake(0.0, 0.0, 40.0, 40.0);
self.imageView.userInteractionEnabled = YES;
[self.imageView addSubview:button];
If you want to have UIButton as completely invisible then you need to remove a line
[button setTitle:#"point" forState:UIControlStateNormal];
since it use to show text on UIButton which make it visible.
This may resolve your issue.