what's the difference between view's hidden = yes and alpha = 0.0f

问题

I have a question about UIView, what's the difference between views hidden, alpha and opaque?

The effect of setting view: hidden = yes and view.alpha = 0.0f is the same.

回答1:

The differences are subtle. According to the UIView class reference:

• opaque tells the system that the view has no transparency and is thus faster to render because calculations for blending can be skipped
• hidden is boolean property that changes only the visibility of the current view and hides it from ui events.
• alpha is an animatable property

Setting alpha = 0.0f or hidden = YES has the same visual effect. However using hidden to actually hide a view not only in a graphical sense but also from ui events might result in a more efficient responder chain when you have lots of nested views.

回答2:

setting view.hidden = yes will hide the view and view.alpha = 0.0f will set the colors of view alpha 0.0 which will make the view invisible, so both are not same.... :)

来源：https://stackoverflow.com/questions/10911696/whats-the-difference-between-views-hidden-yes-and-alpha-0-0f