如何从UIColor对象获得红绿蓝（RGB）和alpha背面？ [英] How do I get red green blue (RGB) and alpha back from a UIColor object?

问题描述

我从这个方法返回一个UIColor：

I am getting a UIColor returned from this method:

- (UIColor *)getUserSelectedColor {   
return [UIColor colorWithRed:redSlider.value green:greenSlider.value blue:blueSlider.value alpha:1.0];
 }

并获得如下颜色：

UIColor *selectedColor = [(ColorPickerView *)alertView getUserSelectedColor];

现在我想从selectedColor获得红色，绿色和蓝色，以便使用这些值。我想要0到1之间的值。

Now I want to get red, green, blue from selectedColor, in order to use those values. I want values between 0 and 1.

推荐答案

访问 SelectedColor.CGColor时崩溃的原因可能是你没有保留 getColor 的结果，也许你需要的是：

The reason for the crash when accessing SelectedColor.CGColor could be that you do not retain the result from getColor, perhaps what you need is:

SelectedColor = [[(ColorPickerView *)alertView getColor] retain];

您只能从 UIColor获取RGB颜色分量使用RGB颜色空间，因为你使用的是 colorWithRed：green：blue：alpha：这不是问题，但如果你的代码有所不同更改。

You can only get the RGB color component from a UIColor that is using the RGB color space, since you are using colorWithRed:green:blue:alpha: that is not a problem, but be vary of this if your code changes.

这样可以让颜色组件变得非常简单：

With this is mind getting the color components is really easy:

const CGFloat* components = CGColorGetComponents(SelectedColor.CGColor);
NSLog(@"Red: %f", components[0]);
NSLog(@"Green: %f", components[1]); 
NSLog(@"Blue: %f", components[2]);
NSLog(@"Alpha: %f", CGColorGetAlpha(SelectedColor.CGColor));

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