假如你有一个值为 @”0A5CEA” (字符串类型的16进制色值) ，可以如下方法创建UIColor对象：
UIColor *color = [UIColor colorwithHexString:@"0A5CEA" alpha:.9];
UIColor Category
然后我们来创建一个UIColor Category，
声明代码 UIColor+fromHex.h ：
@interface UIColor (fromHex) + (UIColor *)colorwithHexString:(NSString *)hexStr alpha:(CGFloat)alpha; @end
implementation代码 UIColor+fromHex.m ：
1 @implementation UIColor (fromHex) 2 3 + (UIColor *)colorwithHexString:(NSString *)hexStr alpha:(CGFloat)alpha; 4 { 5 //----------------------------------------- 6 // Convert hex string to an integer 7 //----------------------------------------- 8 unsigned int hexint = 0; 9 10 // Create scanner 11 NSScanner *scanner = [NSScanner scannerWithString:hexStr]; 12 13 // Tell scanner to skip the # character 14 [scanner setCharactersToBeSkipped:[NSCharacterSet 15 characterSetWithCharactersInString:@"#"]]; 16 [scanner scanHexInt:&hexint]; 17 18 //----------------------------------------- 19 // Create color object, specifying alpha 20 //----------------------------------------- 21 UIColor *color = 22 [UIColor colorWithRed:((CGFloat) ((hexint & 0xFF0000) >> 16))/255 23 green:((CGFloat) ((hexint & 0xFF00) >> 8))/255 24 blue:((CGFloat) (hexint & 0xFF))/255 25 alpha:alpha]; 26 27 return color; 28 } 29 30 @end
第8-15行 对 hex value 转换为 unsigned integer.
第20-24行 创建一个 UIColor object 通过位操作 ‘&’ 计算各RGB颜色值， 同时除以255得到float值。
下面示例代码, 包括十六进制值格式“0x0A5CEA” 和@”#0A5CEA” (后者一般用于web开发):
1 NSString *hexStr1 = @"123ABC"; 2 NSString *hexStr2 = @"#123ABC"; 3 NSString *hexStr3 = @"0x123ABC"; 4 5 UIColor *color1 = [UIColor colorwithHexString:hexStr1 alpha:.9]; 6 NSLog(@"UIColor: %@", color1); 7 8 UIColor *color2 = [UIColor colorwithHexString:hexStr2 alpha:.9]; 9 NSLog(@"UIColor: %@", color2); 10 11 UIColor *color3 = [UIColor colorwithHexString:hexStr3 alpha:.9]; 12 NSLog(@"UIColor: %@", color3);
结果如下：
UIColor: UIDeviceRGBColorSpace 0.0705882 0.227451 0.737255 0.9 UIColor: UIDeviceRGBColorSpace 0.0705882 0.227451 0.737255 0.9 UIColor: UIDeviceRGBColorSpace 0.0705882 0.227451 0.737255 0.9
使用十六进制色值表示UIColor,布布扣,bubuko.com
原文：http://www.cnblogs.com/samniu/p/3804397.html