UIAlertController 实现kvo实现mes文字设置

UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"更新提示" message:[NSString stringWithFormat:@"%@",self.model.groups.update_content]  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];
            NSLog(@"%@",subView5.subviews);
            //取title和message：
            //UILabel *title = subView5.subviews[0];
            UILabel *message = subView5.subviews[1];
            message.textAlignment = NSTextAlignmentLeft;
          
            
            
            [alert addAction:[UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
                
            }]];
            
            [alert addAction:[UIAlertAction actionWithTitle:@"去更新" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
                //点击按钮的响应事件；
                NSURL *url = [NSURL URLWithString:@"http://itunes.apple.com/cn/app/id1198896188?mt=8"];
                
                [[UIApplication sharedApplication]openURL:url];
            }]];
            
            //弹出提示框；
            [self presentViewController:alert animated:true completion:nil];