解除視圖控制器並顯示另一個視圖控制器

Question

• 我有三個ViewController-V1 V2和V3。
• 在V1上單擊一個按鈕，將顯示ViewController V2和動畫FlipHorizo​​ntal。

• 現在，從V2上單擊按鈕，應將ViewController退回到V1並顯示ViewController V3。

  我嘗試了這段代碼來實現此功能。 雖然沒有用。 請幫忙！

注意 ：V2和V3在同一StoryBoard中（開始）。 V1在不同的故事板（主）中。

var VC3 : ViewController3?

        let mainStoryboard: UIStoryboard = UIStoryboard(name: "start",bundle: nil)

 self.dismissViewControllerAnimated(false, completion: {
            self.VC3 = (mainStoryboard.instantiateViewControllerWithIdentifier("ViewController3") as! ViewController3)
            self.presentViewController(self.VC3!, animated: true, completion: nil)
        })

更新 -我收到此警告嘗試在視圖控制器不在窗口層次結構中的ViewController2上顯示ViewController3！

Answer 1

我復制了您的查詢並創建了3個視圖控制器：VC1，VC2和VC3。 我使用Delegates和Segues實現了這一目標。 情節提要設置 。

VC1.Swift：

class VC1: UIViewController, VC2Delegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    func showVC3() {
        self.performSegueWithIdentifier("VC1ToVC3", sender: nil)
    }

    // MARK: - Navigation
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if segue.identifier == "VC1ToVC2" {
            if let destVC = segue.destinationViewController as? VC2 {
                destVC.delegate = self
            }
        }
    }

}

VC2.Swift：

protocol VC2Delegate {
    func showVC3()
}

class VC2: UIViewController {
    var delegate:VC2Delegate?

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    @IBAction func actBack(){
        self.dismissViewControllerAnimated(true, completion: nil)
        if let _ = delegate {
            delegate?.showVC3()
        }
    }

}

Answer 2

警告指出“您正在ViewController2上顯示ViewController3，但是ViewController2在視圖層次結構中不存在！”。 這意味着ViewController2在顯示ViewController3之前已經關閉。 因此，不可能在ViewController2上顯示ViewController 3

使用以下示例代碼：

ViewController1

import UIKit

class ViewController: UIViewController, presentViewControllerThree{

    @IBAction func displayViewControllerTwoOnClick(_ sender: AnyObject) {
        let currentStoryboard: UIStoryboard = UIStoryboard(name: "Start",bundle: nil)
        let  vc2: ViewController2 = currentStoryboard.instantiateViewController(withIdentifier: "viewcont2") as! ViewController2
        vc2.delegate = self
        self.navigationController?.present(vc2, animated: true, completion: nil)
    }

    func presentVC3(){
        let currentStoryboard: UIStoryboard = UIStoryboard(name: "Start",bundle: nil)
        let  vc3: ViewController3 = currentStoryboard.instantiateViewController(withIdentifier: "viewcont3") as! ViewController3

         self.navigationController?.present(vc3, animated: true, completion: nil)
    }

}

ViewController2

 import UIKit

protocol presentViewControllerThree {
    func presentVC3()
}

class ViewController2: UIViewController {

    var delegate: presentViewControllerThree?

    @IBAction func dismissViewControllerOnClick(_ sender: AnyObject) {

        self.dismiss(animated: true, completion: nil)
        delegate?.presentVC3()

    }

}

ViewController3

   import UIKit

class ViewController3: UIViewController {

    @IBAction func dismissViewControllerOnClick(_ sender: AnyObject) {

        self.dismiss(animated: true, completion: nil)
    }


}

Main.storyboard屏幕截圖：

Start.storyboard：

請檢查我的GitHub鏈接以測試示例項目：

https://github.com/k-sathireddy/DismissPresentViewControllers

Answer 3

該錯誤消息具有很強的描述性：

嘗試在視圖控制器不在窗口層次結構中的ViewController2上顯示ViewController3！

讓我們看一下您現有的代碼：

 self.dismissViewControllerAnimated(false, completion: {
            self.VC3 = (mainStoryboard.instantiateViewControllerWithIdentifier("ViewController3") as! ViewController3)

            //Using self here is causing that error
            self.presentViewController(self.VC3!, animated: true, completion: nil)
})

在完成處理程序中，您嘗試從self呈現VC3 ...，但是self指的是您剛剛關閉的ViewController 。 那就是該錯誤消息告訴您的內容。

相反， 您需要從VC2的父級中呈現VC3 。 實現此目標的一種方法是通過presentingViewController屬性：

 self.dismissViewControllerAnimated(false, completion: {
            self.VC3 = (mainStoryboard.instantiateViewControllerWithIdentifier("ViewController3") as! ViewController3)
            self.presentingViewController.presentViewController(self.VC3!, animated: true, completion: nil)
})