ios UIView 的不透明度和 alpha 是一样的吗
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Is the opacity and alpha the same thing for UIView
提问by trillions
I want to use animation to change UIView's color to make it fade, however, somehow i can't access and set opacity, but i can set alpha. I wonder if alpha and opacity are the same? Search on the web and I didnt find a good answer. Thanks a lot for your help!
我想使用动画来更改 UIView 的颜色以使其褪色，但是，不知何故我无法访问和设置不透明度，但我可以设置 alpha。我想知道 alpha 和 opacity 是否相同？在网上搜索，我没有找到好的答案。非常感谢你的帮助！
回答by alex
Actually "opacity" means "value of alpha-channel" of your UIView. When a view is fully opaque this means its alpha = 1, when a view is fully transparent (non-opaque) its alpha = 0.
实际上“不透明度”是指您的 .alpha 通道的“值” UIView。当视图完全不透明时，这意味着它的alpha = 1，当视图完全透明（非不透明）时，它的alpha = 0.
As about properties of CALayerand UIViewin Cocoa, yes, they provide the same functionality.
至于Cocoa的CALayer和属性UIView，是的，它们提供相同的功能。
回答by Cyrille
Just try by yourself!
自己试试吧！
CALayerhas opacityfrom 0 to 1, while UIViewhas alphafrom 0 to 1. They have the same visual effect.
CALayerhas opacityfrom 0 to 1, while UIViewhas alphafrom 0 to 1. 它们具有相同的视觉效果。
回答by Ravindhiran
Alpha affects everything drawn on the view.The background color's alpha affects the background color's transparency and anything else drawn on the view.i.e it brings about a frosty effect to whole view. Opacity means don't draw anything underneath, even if you are transparent, it just effects the current view.
Alpha 影响在视图上绘制的所有内容。背景颜色的 Alpha 影响背景颜色的透明度以及在视图上绘制的任何其他内容。即它会给整个视图带来冷淡的效果。不透明意味着不要在下面绘制任何东西，即使您是透明的，它也只会影响当前视图。
