文字富文本化

  NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:@"啊哈哈哈好烦"];
   //设置文字颜色
    [str addAttribute:NSForegroundColorAttributeName value:[UIColor blueColor] range:NSMakeRange(0,1)];
    [str addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:NSMakeRange(4,2)];
   
   //设置字体
    [str addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:30] range:NSMakeRange(1,3)];
   self.label.attributedText = str;