iOS 中UIButton中文字换行

UIButton *button =[[UIButton alloc]initWithFrame:CGRectMake(100, 100, 200, 40)];
    button.backgroundColor = [UIColor redColor];
    [button setTitle:@"我是Chenhaijian\n   我要换行" forState:UIControlStateNormal];
    button.titleLabel.lineBreakMode = 0;//这句话很重要，不加这句话加上换行符也没用
    [self.view addSubview:button];