//str：要改变的字 
//result：整个label里的字 
//color: 字的颜色
- (NSMutableAttributedString *)changeSomeText:(NSString *)str inText:(NSString *)result withColor:(UIColor *)color {
  NSMutableAttributedString *attributeStr = [[NSMutableAttributedString alloc] initWithString:result];
  NSRange colorRange = NSMakeRange([[attributeStr string] rangeOfString:str].location,[[attributeStr string] rangeOfString:str].length);
  [attributeStr addAttribute:NSForegroundColorAttributeName value:color range:colorRange];

  return attributeStr;
}