ios - UIColor 和 CIColor 它们如何比较，它们有两个的目的是什么？

Question

最近我遇到一些代码，其中尝试获取 UIColor 的 CIColor 属性失败。 UIColor 被初始化为一个简单的 [UIColor blackColor] 并试图获取引发异常的 CIColor。

CIColor *aCIColor = [[UIColor blackColor] CIColor]; //fails

CIColor 和 UIColor 有什么区别，为什么会这样？

Answer 1

CIColor 与 UIColor 一样，用于表示颜色的 channel 维度。

文档中的区别是:

You use CIColor objects in conjunction with other Core Image classes, such as CIFilter, CIContext,and CIImage, to take advantage of the built-in Core Image filters when processing images.

来自 WWDC 2013:

So, because, you know, and CIColor doesn't handle color spaces, it won't do CMYK color, it won't do patterns.

So, these are all things that you're going to lose.

If you ever think that you're going to need that, then probably not the right strategy.

另一种方法，除了我之前已经回答的以外，您可以通过创建 Black UIColor 的 CGColor 来创建 CIColor，例如:

CIColor *color = [CIColor colorWithCGColor:[[UIColor blackColor] CGColor]];