The Alpha and hidden properties of the UIView

When the Alpha property is 0.0, the view is completely transparent and the view is completely opaque at 1.0.

The Hidden property is yes when the view is hidden, otherwise it is not hidden.

Precautions:

1 cannot respond to touch messages when the view is completely transparent or hidden.

That is, when alpha equals 0.0 or hidden is yes, but when alpha<0.01, the view is not receiving the message.

The alpha value of the 2 view affects the drawing of the child view, but the alpha value of the child view does not change.

Original text of the document: This value affects only the current view and does not affect any of its embedded subviews.

The original text is easily misunderstood (or this is a misreading): The alpha value of the view affects only the current view and does not affect its child views.

However, according to the experimental result, the alpha value of the view changes, which does not cause the child view to change its alpha value, but the rendering will affect the child view.

Specific impact: The child view truly renders an alpha value equal to the alpha of the child view by the parent view.

The Alpha and hidden properties of the UIView