互联网 App 中经常会用到 html 颜色值转换 UIColor，比如：#FF9900、0XFF9900 等颜色字符串，以下方法可以将这些字符串转换为 UIColor 对象。
1 #define DEFAULT_VOID_COLOR [UIColor clearColor] 2 3 4 5 6 7 + (UIColor *) colorWithHexString: (NSString *) stringToConvert 8 { 9 NSString *cString = [[stringToConvert stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString]; 10 11 // String should be 6 or 8 characters 12 if ([cString length] < 6) return DEFAULT_VOID_COLOR; 13 14 // strip 0X if it appears 15 if ([cString hasPrefix:@"0X"]) cString = [cString substringFromIndex:2]; 16 if ([cString hasPrefix:@"#"]) cString = [cString substringFromIndex:1]; 17 if ([cString length] != 6) return DEFAULT_VOID_COLOR; 18 // Separate into r, g, b substrings 19 NSRange range; 20 range.location = 0; 21 range.length = 2; 22 NSString *rString = [cString substringWithRange:range]; 23 24 range.location = 2; 25 NSString *gString = [cString substringWithRange:range]; 26 27 range.location = 4; 28 NSString *bString = [cString substringWithRange:range]; 29 30 // Scan values 31 unsigned int r, g, b; 32 [[NSScanner scannerWithString:rString] scanHexInt:&r]; 33 [[NSScanner scannerWithString:gString] scanHexInt:&g]; 34 [[NSScanner scannerWithString:bString] scanHexInt:&b]; 35 36 37 return [UIColor colorWithRed:((float) r / 255.0f) 38 green:((float) g / 255.0f) 39 blue:((float) b / 255.0f) 40 alpha:1.0f]; 41 }