Question

//
//  ViewController.swift
//  FunFacts
//
//  Created by Alex Macleod on 4/10/14.
//  Copyright (c) 2014 Alex Macleod. All rights reserved.
//

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var funFactLabel: UILabel!
    @IBOutlet weak var funFactButton: UIButton!

    @IBOutlet weak var swipeView: UIView!

//    let swipeRec = UISwipeGestureRecognizer()

    let factBook = FactBook()
    let colorWheel = ColorWheel()

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

//        swipeRec.addTarget(self, action: "swipedView")
//        swipeView.addGestureRecognizer(swipeRec)
//        swipeView.userInteractionEnabled = true
        var swipeRight = UISwipeGestureRecognizer(target: self, action: "respondToSwipeGesture:")
        swipeRight.direction = UISwipeGestureRecognizerDirection.Right
        self.view.addGestureRecognizer(swipeRight)

        var swipeLeft = UISwipeGestureRecognizer(target: self, action: "respondToSwipeGesture:")
        swipeLeft.direction = UISwipeGestureRecognizerDirection.Left
        self.view.addGestureRecognizer(swipeLeft)

        var swipeDown = UISwipeGestureRecognizer(target: self, action: "respondToSwipeGesture:")
        swipeDown.direction = UISwipeGestureRecognizerDirection.Down
        self.view.addGestureRecognizer(swipeDown)

        var swipeUp = UISwipeGestureRecognizer(target: self, action: "respondToSwipeGesture:")
        swipeUp.direction = UISwipeGestureRecognizerDirection.Up
        self.view.addGestureRecognizer(swipeUp)

        funFactLabel.text = factBook.randomFact()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }



    func respondToSwipeGesture(gesture: UIGestureRecognizer) {

        if let swipeGesture = gesture as? UISwipeGestureRecognizer {

            switch swipeGesture.direction {
            case UISwipeGestureRecognizerDirection.Right:
//                swipedAlertViewRight()
                self.performSegueWithIdentifier("segueSwipeRight", sender: nil)

            case UISwipeGestureRecognizerDirection.Left:
//                swipedAlertViewLeft()
                swipedLeft()

            case UISwipeGestureRecognizerDirection.Down:
                var randomColor = colorWheel.randomColor()
                view.backgroundColor = randomColor
                funFactButton.tintColor = randomColor

                funFactLabel.text = factBook.randomFact()

            case UISwipeGestureRecognizerDirection.Up:
                var randomColor = colorWheel.randomColor()
                view.backgroundColor = randomColor
                funFactButton.tintColor = randomColor

                funFactLabel.text = factBook.randomFact()

            default:
                break
            }
        }
    }

    func swipedLeft() {

        self.performSegueWithIdentifier("segueSwipeLeft", sender: nil)


    }

//    func swipedAlertViewRight(){
//        let tapAlert = UIAlertController(title: "Swiped", message: "You just swiped right", preferredStyle: UIAlertControllerStyle.Alert)
//        tapAlert.addAction(UIAlertAction(title: "OK", style: .Destructive, handler: nil))
//        self.presentViewController(tapAlert, animated: true, completion: nil)
//    }
//    
//    func swipedAlertViewLeft(){
//        let tapAlert = UIAlertController(title: "Swiped", message: "You just swiped left", preferredStyle: UIAlertControllerStyle.Alert)
//        tapAlert.addAction(UIAlertAction(title: "OK", style: .Destructive, handler: nil))
//        self.presentViewController(tapAlert, animated: true, completion: nil)
//    }

    @IBAction func showFunFact() {
        var randomColor = colorWheel.randomColor()
        view.backgroundColor = randomColor
        funFactButton.tintColor = randomColor

        funFactLabel.text = factBook.randomFact()
    }

}

所以我向左滑动，我将它带到一个新的viewViewcontroller，我向右滑动它带我到另一个空白视图控制器。如何告诉这些空白视图控制器切换回主视图控制器？

Answer 1

该视图控制器中是否有导航栏？

If you do, then you can simply do:

self.navigationController.popViewControllerAnimated(YES)

如果你不这样做，那么你只需要

self.performSegueWithIdentifier("segueSwipeLeft", sender: nil)

（也就是说，对您来自的视图控制器执行segue back ）。 Segues不一定是推动和流行的东西。

Answer 2

Segues创建其视图控制器的实例。这在向前移动时是有意义的，但如果在向后移动时“执行SegueWithIdentifier”，则可能您没有返回到先前的视图控制器，而是您正在创建并呈现之前的新实例查看控制器。

例如，假设您有两个视图控制器，A和B，并且A上有一个文本字段，其中包含用户指定的值。然后你转向B.然后你使用标准的segue回到A.文本将不在A的文本字段中，因为你正在查看A的新实例，而不是该视图控制器的原始实例。 / p>

如果你想备份，有Unwind segues，它是一种特殊的segue，可以让你返回上一个实例。它们被装配到故事板编辑器中场景顶部的绿色“退出”按钮。展开segues（有时称为Exit Segues）非常有趣，因为它们不仅可以让您放松到前一个视图控制器，而且可以一直通过深层视图控制器展开，作为展开的一部分，它们可以在目标上调用不同的方法视图控制器，例如指示在源视图控制器上点击了取消或保存按钮。

以编程方式，如果您的视图控制器是以模态方式呈现的，您还可以使用dismissViewController:animated:completion:进行备份。

我设法转向空白视图控制器。我该怎么回事？

2 个答案: