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问如何使用带有现有UIPageViewController的按钮以编程方式幻灯片视图
EN

Stack Overflow用户

提问于 2018-01-01 08:21:57

回答 1查看 602关注 0票数 0

我正在开发一个有3个主视图的应用程序，为了让用户只需滑动(就像Tinder )就可以改变3个视图，我创建了一个PageViewController，它运行得很好。这个PageViewController的工作方式如下所示。

当用户点击“登录”或"SignUp“按钮时，它将指向PageViewController
PageViewController将firstViewController设置为初始视图
在PageViewController中，它有3种方法，即“getFirst”(获取firstViewController)、“getSecond”(获取secondViewController)、“getThird”(获取thirdViewController)。

我还在每个视图的上部添加了按钮，希望用户能够点击这些按钮滑到其他视图，就像他们在滑动视图时所做的那样(这也像Tinder一样)。

所以在实验中，我在SecondViewController上添加了两个按钮。左边的是移动到FirstViewController，右边的是移动到ThirdViewController。然后，在SecondViewController文件中，我添加了"UIPageViewControllerDelegate“，并尝试为左侧按钮调用”getFirst“方法，并从PageViewController文件中调用右侧按钮的”getThird“方法。

但是当我点击左边的按钮时，我已经在getFirst文件中的“PageViewController”方法行中得到了这个错误消息(我可能也会得到右边按钮的相同错误)。

线程1:致命错误:在展开可选值时意外找到零

密码在下面。

PageViewController

import UIKit

class PageViewController: UIPageViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        self.setViewControllers([getFirst()], direction: .forward, animated: true, completion: nil)
        self.dataSource = self as UIPageViewControllerDataSource
    }
}


extension PageViewController : UIPageViewControllerDataSource {

    //FirstViewController
    @objc func getFirst() -> FirstViewController {
        return storyboard!.instantiateViewController(withIdentifier: "FirstViewController") as! FirstViewController
    }
    //SecondViewController
    @objc func getSecond() -> SecondViewController {
        return storyboard!.instantiateViewController(withIdentifier: "SecondViewController") as! SecondViewController
    }
    //ThirdViewController
    @objc func getThird() -> ThirdViewController {
        return storyboard!.instantiateViewController(withIdentifier: "ThirdViewController") as! ThirdViewController
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
        if viewController.isKind(of: ThirdViewController.self) {
            // 3 -> 2
            return getSecond()
        } else if viewController.isKind(of: SecondViewController.self) {
            // 2 -> 1
            return getFirst()
        } else {
            // 1 -> end of the road
            return nil
        }
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
        if viewController.isKind(of: FirstViewController.self) {
            // 1 -> 2
            return getSecond()
        } else if viewController.isKind(of: SecondViewController.self) {
            // 2 -> 3
            return getThird()
        } else {
            // 3 -> end of the road
            return nil
        }
    }
}

SecondViewController

import UIKit
class SecondViewController: UIViewController, UIPageViewControllerDelegate {

    let pageHelper = PageViewController()
    override func viewDidLoad() {
        super.viewDidLoad()

        pageHelper.delegate = self
    }

    @IBAction func toFirstTapped(_ sender: Any) {
        pageHelper.getFirst()
    }
}

我遗漏了什么？?也许我不能让它以这种方式工作(我不能从其他文件重用PageViewController？)

有人能帮帮我吗！

ios

swift

uipageviewcontroller

回答 1

Stack Overflow用户

回答已采纳

发布于 2018-01-01 11:33:36

首先，PageViewController实例化一个子控制器，该子控制器实例化一个PageViewController。这真的是个好主意吗？然后在您的toFirstTapped中，实例化一个FirstViewController，但是对它什么也不做。

如果你对它什么也不做，你希望它能起什么作用？

在任何情况下，请尝试以下方法：

protocol PageNavigationDelegate : class {
    weak var pageController: PageViewController? { get set }
}

class PageViewController: UIPageViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        self.setViewControllers([getFirst()], direction: .forward, animated: true, completion: nil)
        self.dataSource = self as UIPageViewControllerDataSource
    }
}


extension PageViewController : UIPageViewControllerDataSource {

    func getFirst() -> FirstViewController {
        let controller = storyboard!.instantiateViewController(withIdentifier: "FirstViewController") as! FirstViewController
        controller.pageController = self
        return controller
    }

    func getSecond() -> SecondViewController {
        let controller = storyboard!.instantiateViewController(withIdentifier: "SecondViewController") as! SecondViewController
        controller.pageController = self
        return controller
    }

    func getThird() -> ThirdViewController {
        let controller = storyboard!.instantiateViewController(withIdentifier: "ThirdViewController") as! ThirdViewController
        controller.pageController = self
        return controller
    }

    @discardableResult
    func goToPreviousPage() -> Bool {
        let controller = self.viewControllers!.first!
        if controller.isKind(of: SecondViewController.self) {
            self.setViewControllers([getFirst()], direction: .reverse, animated: true, completion: nil)
            return true
        }

        if controller.isKind(of: ThirdViewController.self) {
            self.setViewControllers([getSecond()], direction: .reverse, animated: true, completion: nil)
            return true
        }

        return false
    }

    @discardableResult
    func goToNextPage() -> Bool {
        let controller = self.viewControllers!.first!
        if controller.isKind(of: FirstViewController.self) {
            self.setViewControllers([getSecond()], direction: .forward, animated: true, completion: nil)
            return true
        }

        if controller.isKind(of: SecondViewController.self) {
            self.setViewControllers([getThird()], direction: .forward, animated: true, completion: nil)
            return true
        }

        return false
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {

        if viewController.isKind(of: SecondViewController.self) {
            return getFirst()
        }

        if viewController.isKind(of: ThirdViewController.self) {
            return getSecond()
        }

        return nil
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {

        if viewController.isKind(of: FirstViewController.self) {
            return getSecond()
        }

        if viewController.isKind(of: SecondViewController.self) {
            return getThird()
        }

        return nil
    }
}

class PageNavigationController : UIViewController, PageNavigationDelegate {
    var pageController: PageViewController?

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    @IBAction func goToPreviousController(_ sender: Any) {
        pageController?.goToPreviousPage()
    }

    @IBAction func goToNextController(_ sender: Any) {
        pageController?.goToNextPage()
    }
}

class FirstViewController: PageNavigationController {

}

class SecondViewController: PageNavigationController {

}

class ThirdViewController: PageNavigationController {

}