UIbutton 换行且不同字体大小颜色设置

(NSAttributedString *)getStrWithSring:(NSString *)leftStr rightStr:(NSString *)rightStr leftColor:(UIColor *)leftColor rightColor:(UIColor *)rightColor {
NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:[NSString stringWithFormat:@"%@\n",leftStr]];
[str addAttribute:NSFontAttributeName value:[UIFont fontWithName:@"PingFangSC-Medium" size:18.0] range:NSMakeRange(0, str.length)];
[str addAttribute:NSForegroundColorAttributeName value:leftColor range:NSMakeRange(0, str.length)];

NSMutableAttributedString *str1 = [[NSMutableAttributedString alloc] initWithString:[NSString stringWithFormat:@"%@",rightStr]];
[str1 addAttribute:NSFontAttributeName value:[UIFont fontWithName:@"PingFangSC-Light" size:12.0] range:NSMakeRange(0, str1.length)];
[str1 addAttribute:NSForegroundColorAttributeName value:rightColor range:NSMakeRange(0, str1.length)];

[str appendAttributedString:str1];
return str;
}