UIAlertController显示内容左对齐

UIAlertController默认居中对齐。找了很多帖子，也没有看到怎么单纯的修改信息内容的左对齐。有的方法改完以后连title都靠左了。不符合我们的预期。直接上代码

    UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"更新提示！" message:tips preferredStyle:UIAlertControllerStyleAlert];    UIView *subView1 = alert.view.subviews[0];    UIView *subView2 = subView1.subviews[0];    UIView *subView3 = subView2.subviews[0];    UIView *subView4 = subView3.subviews[0];    UIView *subView5 = subView4.subviews[0];//分别拿到title 和 message 可以分别设置他们的对齐属性    UILabel *title = subView5.subviews[0];    UILabel *message = subView5.subviews[1];    message.textAlignment = NSTextAlignmentLeft;