swift - PageViewController 中的每个页面都有一个 UINavigationBar 标题

Question

我已经用一组 ViewController 设置了我的 pageViewController(嵌入在 NavigationController 中)以用作页面(如下所示):

`
class PageViewController: UIPageViewController {

    var arrayIndex: Int = 0
    var navigationBar = UINavigationBar()
    var pageControl = UIPageControl.self





    override func viewDidLoad() {
        super.viewDidLoad()

        dataSource = self



        if let firstViewController = orderedViewControllers.first {
            setViewControllers([firstViewController],
                               direction: .Forward,
                               animated: true,
                               completion: nil)
        }




    }


    // set up & order all view controllers

    private(set) lazy var orderedViewControllers: [UIViewController] = {
        return [self.newDayViewController("monday"),
                self.newDayViewController("tuesday"),
                self.newDayViewController("wednesday"),
                self.newDayViewController("thursday")//,
                self.newDayViewController("friday"),
                self.newDayViewController("saturday"),
                self.newDayViewController("sunday")
        ]


    }()






    // instantiate view controllers above that contain 'day' (easiest method to differentiate from other controllers)

    private func newDayViewController(day: String) -> UIViewController {
        return UIStoryboard(name: "Main", bundle: nil) .
            instantiateViewControllerWithIdentifier("\(day)")
    }


    func pageViewController(pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
        if (!completed) {
            return
        }

         arrayIndex =  Int(pageViewController.viewControllers!.first!.view.restorationIdentifier!)!


        switch arrayIndex {

        case 0:
            navigationBar.topItem!.title = "Monday"
            break

        case 1:
            navigationBar.topItem!.title = "Tuesday"
            break

        case 2:
            navigationBar.topItem!.title = "Wednesday"
            break

        case 3:
            navigationBar.topItem!.title = "Thursday"
        default:
            navigationBar.topItem!.title = "Timetable"


        }
    }








}


extension PageViewController: UIPageViewControllerDataSource {




    func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
        guard let viewControllerIndex = orderedViewControllers.indexOf(viewController) else {
            return nil
        }



        let previousIndex = viewControllerIndex - 1


        guard previousIndex >= 0 else {
            return orderedViewControllers.last
        }

        guard orderedViewControllers.count > previousIndex else {
            return nil
        }

        return orderedViewControllers[previousIndex]
    }

    func pageViewController(pageViewController: UIPageViewController,
                            viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
        guard let viewControllerIndex = orderedViewControllers.indexOf(viewController) else {
            return nil
        }

        let nextIndex = viewControllerIndex + 1
        let orderedViewControllersCount = orderedViewControllers.count




        //MARK: - determine which viewController the user is on



        guard orderedViewControllersCount != nextIndex else {
            return orderedViewControllers.first
        }

        guard orderedViewControllersCount > nextIndex else {
            return nil
        }

        return orderedViewControllers[nextIndex]
    }

    func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int {
        return orderedViewControllers.count
    }

    func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {
        guard let firstViewController = viewControllers?.first,
            firstViewControllerIndex = orderedViewControllers.indexOf(firstViewController) else {
                return 0
        }

        return firstViewControllerIndex
    }


}

`

我想知道如何让用户在浏览页面 View 时，UINavigationBar 的标题更改为他们正在查看的 View 的标题？例如:当用户查看 mondayViewController 时，标题是星期一，他们可以滑动到星期二，标题会改变等等。

欢迎提出建议

谢谢!

Answer 1

您的代码中存在一些错误，首先没有 UIPageViewControllerDelegate，因此永远不会调用委托(delegate)方法。

然后，我不知道你的PageViewController是否真的有一个UINavigationController。为了确保您可以通过选择您的 PageViewController 来嵌入它，并制作与图片中制作的相同的东西:

所以你可以在 Storyboard中看到 UINavigationController 和 UIPageViewController，如下所示:

在你用每个 Storyboard ID 创建了一整天的 UIViewController 之后，例如星期一:

您可以像下面的代码一样修改您的代码:

   import UIKit
    class PageViewController: UIPageViewController,UIPageViewControllerDelegate {
        var arrayIndex: Int = 0
        var pageControl = UIPageControl.self
        private(set) lazy var orderedViewControllers: [UIViewController] = {
            return [self.newDayViewController("monday"),
                    self.newDayViewController("tuesday"),
                    self.newDayViewController("wednesday"),
                    self.newDayViewController("thursday"),
                    self.newDayViewController("friday"),
                    self.newDayViewController("saturday"),
                    self.newDayViewController("sunday")
            ]
        }()

        override func viewDidLoad() {
            super.viewDidLoad()

            dataSource = self
            delegate = self
            if let firstViewController = orderedViewControllers.first {
                self.navigationController!.navigationBar.topItem!.title = "monday"
                setViewControllers([firstViewController],
                                   direction: .Forward,
                                   animated: true,
                                   completion: nil)
            }
        }

        private func newDayViewController(day: String) -> UIViewController {
            return UIStoryboard(name: "Main", bundle: nil) .
                instantiateViewControllerWithIdentifier("\(day)")
        }

        func pageViewController(pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
            if (!completed) {
                return
            }

            if let firstViewController = viewControllers?.first,
                let arrayIndex = orderedViewControllers.indexOf(firstViewController) {
                switch arrayIndex {
                case 0:
                    self.navigationController!.navigationBar.topItem!.title = "Monday"
                    break

                case 1:
                     self.navigationController!.navigationBar.topItem!.title = "Tuesday"
                    break

                case 2:
                     self.navigationController!.navigationBar.topItem!.title = "Wednesday"
                    break

                case 3:
                     self.navigationController!.navigationBar.topItem!.title = "Thursday"
                default:
                     self.navigationController!.navigationBar.topItem!.title = "Timetable"


                }
            }
        }
    }
    extension PageViewController: UIPageViewControllerDataSource {
        func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
            guard let viewControllerIndex = orderedViewControllers.indexOf(viewController) else {
                return nil
            }
            let previousIndex = viewControllerIndex - 1
            guard previousIndex >= 0 else {
                return orderedViewControllers.last
            }
            guard orderedViewControllers.count > previousIndex else {
                return nil
            }
            return orderedViewControllers[previousIndex]
        }

        func pageViewController(pageViewController: UIPageViewController,
                                viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
            guard let viewControllerIndex = orderedViewControllers.indexOf(viewController) else {
                return nil
            }
            let nextIndex = viewControllerIndex + 1
            let orderedViewControllersCount = orderedViewControllers.count
            //MARK: - determine which viewController the user is o
            guard orderedViewControllersCount != nextIndex else {
                return orderedViewControllers.first
            }
            guard orderedViewControllersCount > nextIndex else {
                return nil
            }
            return orderedViewControllers[nextIndex]
        }
        func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int {
            return orderedViewControllers.count
        }
        func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {
            guard let firstViewController = viewControllers?.first,
                firstViewControllerIndex = orderedViewControllers.indexOf(firstViewController) else {
                    return 0
            }
            return firstViewControllerIndex
        }
    }