UIColor 拓展：16进制色值取颜色

转自：http://blog.csdn.net/wudidalishi/article/details/8028307
注：本宝宝留作笔记参考，感谢作者

• (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];
  }