iOS Button显示两行标题

```

UIButton *btn = [UIButton buttonWithType:(UIButtonTypeCustom)];

btn.backgroundColor =[UIColor greenColor];

btn.frame = CGRectMake(50, 100, 200, 60);

[btn setTitle:@"fengfeng\nNewfengfeng" forState:(UIControlStateNormal)];

btn.titleLabel.textAlignment = NSTextAlignmentCenter;

btn.titleLabel.lineBreakMode = NSLineBreakByWordWrapping;

btn.titleLabel.numberOfLines = 2;

[self.view addSubview:btn];

```

重点在于在两行标题中间加\n

之前我总是往button上加两个label，但是这样的话按钮的点击事件就会失效，而且处理起来非常的麻烦。这个方法帮我解决了很多问题。