UIColor 工具

有時候美工給的是十六進制的顏色值，所以我寫了個方法來進行轉化：

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

@interface UIColor (UIColor)
+ (UIColor *)colorWithHexValue:(NSUInteger)hexValue alpha:(CGFloat)alpha;//eg. self.window.backgroundColor = [UIColor colorWithHexValue:0x123456 alpha:0.8];
@end

#import "UIColor+UIColor.h"

@implementation UIColor (UIColor)
+ (UIColor *)colorWithHexValue:(NSUInteger)hexValue alpha:(CGFloat)alpha
{
    return [UIColor colorWithRed:((hexValue >> 16) & 0x000000FF)/255.0f
                           green:((hexValue >> 8) & 0x000000FF)/255.0f
                            blue:((hexValue) & 0x000000FF)/255.0
                           alpha:alpha];
}
@end