Swift 3 - UIPageViewController - 不鼓励在分离的视图控制器上呈现视图控制器

Question

我正在使用 UIPageViewController 来打开我的应用程序。第三页是我的登录页面。这包含 facebook 登录。当我单击 facebook 登录按钮 时，打开空白页面和 xcode 给我这个输出 “不鼓励在分离的视图控制器上显示视图控制器 。”

当 我不使用 UIPageViewController 时，此按钮有效。所以有我的代码。我该如何解决这个问题？

import UIKit

class MyPageViewController: UIPageViewController, 
UIPageViewControllerDataSource, UIPageViewControllerDelegate {

var pageContainer: UIPageViewController!
// The pages it contains
var pages = [UIViewController]()

// Track the current index
var currentIndex: Int?
private var pendingIndex: Int?

override func viewDidLoad() {
    super.viewDidLoad()
    // Setup the pages
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let page1: UIViewController! = storyboard.instantiateViewController(withIdentifier: "firstVC")
    let page2: UIViewController! = storyboard.instantiateViewController(withIdentifier: "secondVC")
    let page3: UIViewController! = storyboard.instantiateViewController(withIdentifier: "LoginPage")
    pages.append(page1)
    pages.append(page2)
    pages.append(page3)

    pageContainer = UIPageViewController(transitionStyle: .scroll, navigationOrientation: .horizontal, options: nil)
    pageContainer.delegate = self
    pageContainer.dataSource = self
    pageContainer.setViewControllers([page1], direction: UIPageViewControllerNavigationDirection.forward, animated: false, completion: nil)
    // Add it to the view
    view.addSubview(pageContainer.view)

}

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

    let currentIndex = pages.index(of: viewController)!
    if currentIndex == 0 {
        return nil
    }
    let previousIndex = abs((currentIndex - 1) % pages.count)
    return pages[previousIndex]
}

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

    let currentIndex = pages.index(of: viewController)!
    if currentIndex == pages.count-1 {
        return nil
    }
    let nextIndex = abs((currentIndex + 1) % pages.count)
    return pages[nextIndex]

}

func pageViewController(_ pageViewController: UIPageViewController, willTransitionTo pendingViewControllers: [UIViewController]) {
    pendingIndex = pages.index(of: pendingViewControllers.first!)
}

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

}

我也可以试试这个

let page3: UIViewController! = storyboard.instantiateViewController(withIdentifier: "LoginPage")

到这里

let page3: UIViewController! = storyboard.instantiateViewController(withIdentifier: "LoginPage") as! LoginPage

或者这个

let page3: LoginPage! = storyboard.instantiateViewController(withIdentifier: "LoginPage") as! LoginPage

没用。

Answer 1

为您的LoginPage 控制器创建delegate，该控制器具有通知Facebook 登录按钮按下的功能。像这样的：

protocol LoginPageDelegate: class {
    func loginPageDidPressFacebookButton(_ controller: LoginPage)
}

现在将 delegate 属性添加到您的 LoginPage 类中

class LoginPage: UIViewController {
    weak var delegate: LoginPageDelegate?
}

现在你需要在用户按下Facebook login button时通知代理

@IBAction func facebookButtonPressed(button: UIButton) {
    self.delegate?.loginPageDidPressFacebookButton(self)
}

您不能在MyPageViewController 中订阅此delegate。

首先你需要使它的类符合LoginPageDelegate

 class MyPageViewController: UIPageViewController,
UIPageViewControllerDataSource, UIPageViewControllerDelegate, LoginPageDelegate {

    //MARK: LoginPageDelegate methods

    func loginPageDidPressFacebookButton(_ controller: LoginPage) {
        //present what you need here
    }
}

现在在你给你看之前LoginPage：

let page3: LoginPage! = storyboard.instantiateViewController(withIdentifier: "LoginPage")
    page3.delegate = self