NSString *str1 = @"1111";
NSString *str2 = @"2222";
[self customizeStr:str1 colorStr:str2];
}

• (void)customizeStr:(NSString *)str colorStr:(NSString *)colorStr
  {
  NSString *apendStr = [NSString stringWithFormat:@"%@%@",str,colorStr];
  NSMutableAttributedString *customizeStr = [[NSMutableAttributedString alloc]initWithString:apendStr];
  NSDictionary *atr = @{NSFontAttributeName:[UIFont boldSystemFontOfSize:18],NSForegroundColorAttributeName:[UIColor greenColor]};
  NSRange colorStrRan = NSMakeRange(2, 4);
  [customizeStr setAttributes:atr range:colorStrRan];
  _colorLabel.attributedText = customizeStr;
  }