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];