为 UIColor 类增加 RandomColor 方法

UIColor+RandomColor.h

//.h
#import <UIKit/UIKit.h>

@interface UIColor (RandomColor)
+(UIColor *) randomColor;
@end



//.m
#import "UIColor+RandomColor.h"

@implementation UIColor (RandomColor)
+(UIColor *) randomColor
{
    CGFloat hue = ( arc4random() % 256 / 256.0 );  //  0.0 to 1.0
    CGFloat saturation = ( arc4random() % 128 / 256.0 ) + 0.5;  //  0.5 to 1.0, away from white
    CGFloat brightness = ( arc4random() % 128 / 256.0 ) + 0.5;  //  0.5 to 1.0, away from black
    return [UIColor colorWithHue:hue saturation:saturation brightness:brightness alpha:1];
}
@end


//引用这个 category，然后可以直接调用这个 randomColor 方法了。

via: here

RGB 取色：

[UIColor colorWithRed:237/255.0  green:237/255.0 blue:237/255.0 alpha:1.0]; 

// or
#define COLOR_WITH_RGBA(r,g,b,a) [UIColor colorWithRed:(r)/255.0 green:(g)/255.0 blue:(b)/255.0 alpha:(a)]