Bar button item custom view not detecting UITapGesture

Question

Created Sep ’20

Replies 3

Boosts 0

Views 2.2k

Participants 3

I am encountering some weird behavior, where a subview within a UIBarButtonItem.customView is not firing the tapGesture.

Code Block private var leftBarButtonItem: UIBarButtonItem = {
	let b = UIBarButtonItem()
	return b
}()
private lazy var imageView: UIImageView = {
	let iv = UIImageView()
	//... some adicional setup
	iv.isUserInteractionEnabled = true
	return iv
}()
func setupBBItem() {
	let holderView = UIView()
	holderView.isUserInteractionEnabled = true
	
	holderView.addSubview(imageView)
	imageView.frame = //... some frame
	//... more setups here
	
	holderView.isUserInteractionEnabled = true
	
	
	leftBarButtonItem.customView = holderView
	navigationItem.leftBarButtonItem = leftBarButtonItem
	
	let gesture = UITapGestureRecognizer(target: self, action: #selector(someFunction))
	imageView.addGestureRecognizer(gesture)
}
@objc private func someFunction() {
  print("tap gesture detected")
}

I have even tried to add the gesture to the holderView instead, but the result is the same, the function never fires.

Am I missing something here?

Answered by ivancantarino in 636358022

So, I have figured this out.

The problem was that I wasn't applying any constraints to the holderView, so even though the views were shown, the actual size was 0, because it was visible out of bounds.

Note that setting a CGRect size to the holderView didn't solve the issue. I really had to set its constraints to the superview - in this case the leftBarButtonItem.customView

Boost

Answer 1

Claude31 OP

Sep ’20

You create imageView without giving any image. Hence it has zero size.

Could be that causes the problem.

Try to change init :

Code Block 	let iv = UIImageView(image: someImage)

0

Answer 2

ivancantarino OP

Sep ’20

Accepted Answer

So, I have figured this out.

The problem was that I wasn't applying any constraints to the holderView, so even though the views were shown, the actual size was 0, because it was visible out of bounds.

Note that setting a CGRect size to the holderView didn't solve the issue. I really had to set its constraints to the superview - in this case the leftBarButtonItem.customView

0

Answer 3

OOPer OP

Sep ’20

In setupBBItem(), you create holderView with let holderView = UIView().
The no-argument initializer of UIView is not documented, but I guess it generates a UIView of size zero.

Try giving it some size.

Code Block         let holderView = UIView(frame: CGRect(x: 0, y: 0, width: 30, height: 44))

Seems you have found another solution.
But as far as I tried, constraints are not needed if initialized with frame.

0