Unresponsive UIButton in subview added to UIStackView

Question

In the detailViewController of a UISplitView I have subviews added to a UIStackView inside a UIScrollView.

Just using system buttons without subviews or images, results in responsive buttons, but subviews seem to interfere.

Enabling touch is specifically coded. I have attempted to keep each view inside the containing view so there will be no overlap to invalidate receiving touch events, but not sure if this is done properly. Each subview contains a label and a custom button with an image. The subview is then added to the stackview, and the stackview to the scrollview.

Thanks for any help.

override func viewDidLoad() {
    super.viewDidLoad()

    scrollView = UIScrollView()
    scrollView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(scrollView)

    // Constrain the scroll view within the detailView
    view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|[scrollView]|", options: .AlignAllCenterX, metrics: nil, views: ["scrollView": scrollView]))
    view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|[scrollView]|", options: .AlignAllCenterX, metrics: nil, views: ["scrollView": scrollView]))


    stackView = UIStackView()

    stackView.frame = CGRectMake(0,0,view.frame.width, 1000)
    stackView.translatesAutoresizingMaskIntoConstraints = false
    stackView.axis = .Vertical
    scrollView.contentSize = CGSizeMake(400, 1000)
    scrollView.addSubview(stackView)

    // Constrain the stackView within the scrollView
scrollView.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|[stackView]|", options: NSLayoutFormatOptions.AlignAllCenterX, metrics: nil, views: ["stackView": stackView]))
scrollView.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|[stackView]", options: NSLayoutFormatOptions.AlignAllCenterX, metrics: nil, views: ["stackView": stackView]))


    let selectedGroup: Group = GroupArray[5]

    let descriptorsArray = selectedGroup.descriptorsArray

    for descriptor in descriptorsArray {
        // Create a subview for each descriptor

        let subView = UIView()
        subView.frame = CGRectMake(0 , 0, self.stackView.frame.width-10, 54)
        subView.backgroundColor = UIColor.yellowColor()

        subView.heightAnchor.constraintEqualToConstant(54.0).active = true
        // Create a label for Descriptor subview

        let label = UILabel(frame: CGRectMake(20, 0, 200, 50))
        label.text = descriptor.name
        label.font = UIFont.boldSystemFontOfSize(22.0)
        label.textAlignment = .Left
        label.textColor = UIColor.brownColor()
        label.backgroundColor = UIColor.greenColor()
        label.heightAnchor.constraintEqualToConstant(50.0).active = true
        subView.addSubview(label)

        // Create a button for Checkbox
        let btn = UIButton()
        btn.frame = CGRectMake(220, 0, 50, 50)
        btn.backgroundColor = UIColor.blueColor()
        btn.setImage(UIImage(named:"checked.png"), forState: UIControlState.Normal)

        btn.heightAnchor.constraintLessThanOrEqualToConstant(50.0)
        btn.widthAnchor.constraintLessThanOrEqualToConstant(50.0)

        btn.addTarget(self, action: "btnPressed:", forControlEvents: UIControlEvents.TouchUpInside)

        subView.addSubview(btn)
        btn.userInteractionEnabled = true
        subView.userInteractionEnabled = true
        stackView.userInteractionEnabled = true
        scrollView.userInteractionEnabled = true
        stackView.addArrangedSubview(subView)


    }
}

func btnPressed(sender: UIButton!) {

    print("btn Pressed")

}

Answer 1

It seems to be that something is lying over your button and catching all the touch events.

1. Never turn on userInterectionEnabled if you don't need it

There is no reason why a normal view like subView should have set userInteractionEnabled set to true so put it to false.

2. Find the bug:

To find out witch view catches the event start your app on a device and navigate to the stackView. Now in Xcode, press the button "Debug View Hierarchy" (placed right over the console output)

After that you will see every view currently displayed on your device. What you do now is finding out wich views are above your button, and then in code turn their userInteractionEnabled value to false.