Does UIButton become disabled when its alpha is set to 0.0?

monodevelop, xamarin.ios, xcode

Solution

As per Apple's documentation for `UIView`'s `hitTest:withEvent:` method:

This method ignores view objects that are hidden, that have disabled user interactions, or have an alpha level less than 0.01.

So any `UIView` that has alpha lower than 0.01 will be ignored by the touch events processing system, i.e. will not receive touch.

Problem

I have a few buttons in my app whose alpha is currently set to zero. These buttons are completely non-responsive, but as soon as I increase their alpha, they begin to respond. Is this expected behavior?

Original source