UIAlertController警告视图和操作表单

//创建一个myAlert1操作表单对象(UIAlertControllerStyleActionSheet为操作表单，UIAlertControllerStyleAlert为警告视图) 
  UIAlertController *myAlert1 = [UIAlertController alertControllerWithTitle:@"Are you sure?" message:nil preferredStyle:UIAlertControllerStyleActionSheet];
    //创建一个操作表中的按钮对象(警告框、操作表默认没有按钮)
    //参数handler参数是个块，具体实现点击这个按钮所需处理的内容
    UIAlertAction *yesAction = [UIAlertAction actionWithTitle:@"Yes" style:UIAlertActionStyleDestructive handler:^(UIAlertAction *action){
        
        NSString *msg;
        if ([self.nameText.text length] > 0) {
            msg = [NSString stringWithFormat:@"Your name is %@",self.nameText.text];
    
        }else{
            msg = @"You haven't input";
        }
        
        UIAlertController *myAlert2 = [UIAlertController alertControllerWithTitle:@"Something Was Done" message:msg preferredStyle:UIAlertControllerStyleAlert];
        
        UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"Phew!" style:UIAlertActionStyleCancel handler:nil];
    //往myAlert2警告框对象中添加这个cancel按钮
        [myAlert2 addAction:cancelAction];
    //在屏幕中绘制警告框对话框
        [self presentViewController:myAlert2 animated:YES completion:nil];
    }];
    UIAlertAction *noAction = [UIAlertAction actionWithTitle:@"No way!" style:UIAlertActionStyleCancel handler:nil];
    
    [myAlert1 addAction:yesAction];
    [myAlert1 addAction:noAction];
    
    //------这段代码开发iPhone app时可不写,iPad必须要写-------
    UIPopoverPresentationController *ppc = myAlert1.popoverPresentationController;
    
    if (ppc != nil) {
        ppc.sourceView = sender;
        ppc.sourceRect = sender.bounds;
        //设置iPad操作表单的属性，使箭头方向为往下指
        ppc.permittedArrowDirections = UIPopoverArrowDirectionDown;
    }
    //------这段代码开发iPhone app时可不写,iPad必须要写-------
    
    [self presentViewController:myAlert1 animated:YES completion:nil];