从UIViewController回到第一个ViewController

Question

手头的问题如下：我展示了一个UIAlertController。如果用户按下删除键，则视图应该返回到class TableViewQuery: PFQueryTableViewController类的第一页。

import UIKit 

class DetailViewController: UIViewController { 

    var currentObject : PFObject? 


      @IBAction func pressDelete(sender: AnyObject) { 

       let deleteUser = UIAlertController(title: "Are you sure?", message: "Are you sure you want to delete the current user?", preferredStyle: UIAlertControllerStyle.Alert) 
       deleteUser.addAction(UIAlertAction(title: "Yes", style: .Default, handler: { (action: UIAlertAction) -> Void in 

        // Unwrap current object 
        if let object = self.currentObject { 
         object["firstName"] = self.firstName.text 
         object["lastName"] = self.lastName.text    
         object.deleteEventually() 
        } 

      })) 
      deleteUser.addAction(UIAlertAction(title: "Cancel", style: .Cancel, handler: { (action: UIAlertAction) -> Void in 
       //Do nothing 
      })) 


      presentViewController(deleteUser, animated: true, completion: nil)   
    } 

我已经试过self.dismissViewControllerAnimated(true, completion: nil)，但只是关闭UIAlertController。

我也尝试了unwind segue，但是当它按下按钮时，它立即做到了，而不是显示UIAlertController。

我也试过segueForUnwindingToViewController(<toViewController: UIViewController:UIViewController>, fromViewController: <#T##UIViewController#>, identifier: <#T##String?#>)但是我的toViewController不是UIViewController，而是PFQueryTableViewController。

我还有什么可以尝试的任何想法？

Answer 1

当用户单击YES时，您应该将代码放入UIAlertAction的处理程序中以进行响应。我想你正在使用主细节视图控制器。如果是这样，你需要找到正确的导航控制器弹出。否则，如果您正在使用导航控制器，只需按照我评论的代码弹出即可。

@IBAction func pressDelete(sender: AnyObject) { 
    let deleteUser = UIAlertController(title: "Are you sure?", message: "Are you sure you want to delete the current user?", preferredStyle: UIAlertControllerStyle.Alert) 
    deleteUser.addAction(UIAlertAction(title: "Yes", style: .Default, handler: { (action: UIAlertAction) -> Void in 
     // If you are using master detail view controllers 
     if let navController = self.splitViewController?.viewControllers[0] as? UINavigationController { 
      navController.popViewControllerAnimated(true) 
     } 
     // If you using navigation controller 
     // self.navigationController?.popViewControllerAnimated(true) 
    })) 
    deleteUser.addAction(UIAlertAction(title: "Cancel", style: .Cancel, handler: { (action: UIAlertAction) -> Void in 
     //Do nothing 
    })) 


    presentViewController(deleteUser, animated: true, completion: nil) 
} 

Answer 2

您应该使用presentViewController的完成处理程序。您可能需要跟踪用户使用警报视图控制器执行的任何操作。您必须使用警报视图控制器操作来跟踪用户的选择。然后在完成处理程序中检查用户的选择，然后相应地进行导航。

var didTapDeleteButton = false 

     @IBAction func pressDelete(sender: AnyObject) { 

      let deleteUser = UIAlertController(title: "Are you sure?", message: "Are you sure you want to delete the current user?", preferredStyle: UIAlertControllerStyle.Alert) 
      deleteUser.addAction(UIAlertAction(title: "Yes", style: .Default, handler: { (action: UIAlertAction) -> Void in 

       // Unwrap current object 
       if let object = self.currentObject { 
        object["firstName"] = self.firstName.text 
        object["lastName"] = self.lastName.text    
        object.deleteEventually() 

        didTapDeleteButton = true 
       } 

     })) 
     deleteUser.addAction(UIAlertAction(title: "Cancel", style: .Cancel, handler: { (action: UIAlertAction) -> Void in 
      didTapDeleteButton = false 
     })) 

     presentViewController(viewController, animated: true, completion: { 

      // Make navigation choice here 
      if didTapDeleteButton == true { 
       // Navigation option 1 
      } else { 
       // Navigation option 2 
      } 

     })