检测不在UISubView上的轻击手势

Question

I have three UIButton instances: buttonA , buttonB and buttonC . Each button has its own center and occupies a certain size.

I want these buttons to "do something" (ie have the alpha values change) when the the screen is tapped anywhere except for where the buttons are, such that one can pressed the buttons to have their action s triggered without "doing this something" happening.

What's the best way to go about this, please?

Answer 1

Try something like this:

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    // Get location of touch
    let pos = touches.first?.location(in: self.view)

    if !b.frame.contains(pos) && !b2.frame.contains(pos) && !b3.frame.contains(pos) {
        // Change alpha or do something else
    }
}

Where b, b2, and b3 are each of your buttons.

Answer 2

This works like any other tap. Just give the "elsewhere" (eg the view controller's main view) a UITapGestureRecognizer and respond when the user taps it. It won't be triggered when you tap one of the buttons, because in that case the button will eat the tap.