我正在使用 Xcode 6 GM。我正在尝试实现这个 page view controller tutorial但是在 Swift 而不是 Objective-C 中，它没有按预期工作。

我实际上找到了 git repo其他人也在做同样的事情，但是在克隆他们的项目并在 Xcode 中打开它之后，它出现了与我相同的错误。除了实现 UIPageViewControllerDataSource 协议(protocol)时的协议(protocol)一致性问题外，我已经设法解决了其中的大部分问题。

老实说，我不完全理解 ? 和 ! 在 Swift 中的用法，以及这是否导致了我的问题。删除!来自协议(protocol)方法实现中的变量导致其他错误。

有人可以帮忙吗？

class ViewController: UIViewController, UIPageViewControllerDataSource {

var pageViewController : UIPageViewController?
var pageTitles = ["Over 200 Tips and Tricks", "Discover Hidden Features", "Bookmark Favorite Tip", "FreeRegular Update"]
var pageImages = ["page1.png", "page2.png", "page3.png", "page4.png"]
var currentIndex = 0

@IBAction func startWalkthrough(sender: UIButton) {
    var startingViewController : PageContentViewController = self.viewControllerAtIndex(0)!
    var viewControllers : NSArray = [startingViewController]
    self.pageViewController!.setViewControllers(viewControllers, direction: .Forward, animated: false, completion: nil)
}

override func viewDidLoad() {
    super.viewDidLoad()

    //Create page view controller
    self.pageViewController = UIPageViewController(transitionStyle: .Scroll, navigationOrientation: .Horizontal, options: nil)
    self.pageViewController!.dataSource = self

    let startingViewController : PageContentViewController = self.viewControllerAtIndex(0)!
    let viewControllers: NSArray = [startingViewController]
    self.pageViewController!.setViewControllers(viewControllers, direction: .Forward, animated: false, completion: nil)

    // Change the size of page view controller
    self.pageViewController!.view.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height - 30);

    self.addChildViewController(self.pageViewController!)
    self.view.addSubview(self.pageViewController!.view)
    self.pageViewController!.didMoveToParentViewController(self)

}

func pageViewController(pageViewController: UIPageViewController!,
    viewControllerBeforeViewController viewController: UIViewController!) -> UIViewController! {

        var index = (viewController as PageContentViewController).pageIndex

        if index == 0 || index == NSNotFound {
            return nil
        }

        index!--

        println("Decreasing Index: \(index)")

        return self.viewControllerAtIndex(index!)
}

func pageViewController(pageViewController: UIPageViewController!,
    viewControllerAfterViewController viewController: UIViewController!) -> UIViewController! {

        var index = (viewController as PageContentViewController).pageIndex

        if index == NSNotFound {
            return nil
        }

        index!++

        println("Increasing Index: \(index)")

        if index == self.pageTitles.count {
            return nil;
        }
        return self.viewControllerAtIndex(index!);
}

func viewControllerAtIndex(index : Int) -> PageContentViewController? {

    if self.pageTitles.count == 0 || index >= self.pageTitles.count {
        return nil;
    }

    // Create a new view controller and pass suitable data.
    let pageContentViewController = self.storyboard!.instantiateViewControllerWithIdentifier("PageContentViewController") as PageContentViewController
    pageContentViewController.imageFile = self.pageImages[index]
    pageContentViewController.titleText = self.pageTitles[index]
    pageContentViewController.pageIndex = index

    return pageContentViewController;
}

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

func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {
    return 0
}
}

最佳答案

这是因为 UIPageViewControllerDataSource 协议(protocol)更新了方法签名 - 您正在使用:

func pageViewController(pageViewController: UIPageViewController!, viewControllerBeforeViewController viewController: UIViewController!) -> UIViewController!

func pageViewController(pageViewController: UIPageViewController!, viewControllerAfterViewController viewController: UIViewController!) -> UIViewController!

但现在他们是:

func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController?

func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController?

当您对不符合协议(protocol)的协议(protocol)有疑问时，按住 Command 并单击协议(protocol)名称会将您带到协议(protocol)声明，您可以在其中查看是否正确实现了其接口(interface)

关于ios - Swift:类型 'ViewController' 不符合协议(protocol) 'UIPageViewControllerDataSource'，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/25831897/