ios開發之16進制顏色(html顏色值)字符串轉爲UIColor

互聯網 App 中常常會用到 html 顏色值轉換 UIColor，好比：#FF9900、0XFF9900 等顏色字符串，如下方法能夠將這些字符串轉換爲 UIColor 對象。

+ (UIColor *) colorWithHexString: (NSString *)color
{
   NSString *cString = [[color stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];

   // String should be 6 or 8 characters
   if ([cString length] < 6) {
       return [UIColor clearColor];
   }

   // strip 0X if it appears
   if ([cString hasPrefix:@"0X"])
       cString = [cString substringFromIndex:2];
   if ([cString hasPrefix:@"#"])
       cString = [cString substringFromIndex:1];
   if ([cString length] != 6)
       return [UIColor clearColor];

   // Separate into r, g, b substrings
   NSRange range;
   range.location = 0;
   range.length = 2;

   //r
   NSString *rString = [cString substringWithRange:range];

   //g
   range.location = 2;
   NSString *gString = [cString substringWithRange:range];

   //b
   range.location = 4;
   NSString *bString = [cString substringWithRange:range];

   // Scan values
   unsigned int r, g, b;
   [[NSScanner scannerWithString:rString] scanHexInt:&r];
   [[NSScanner scannerWithString:gString] scanHexInt:&g];
   [[NSScanner scannerWithString:bString] scanHexInt:&b];

   return [UIColor colorWithRed:((float) r / 255.0f) green:((float) g / 255.0f) blue:((float) b / 255.0f) alpha:1.0f];
}