UIPageViewController - 不符合协议

Question

我想实现一个UIPageViewController和我收到以下错误：我的代码如下

import UIKit 

class ShopViewController: UIPageViewController, UIPageViewControllerDataSource { 

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

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

这给了我一个错误，指出：ShopViewController不符合协议UIPageViewControllerDataSource。

于是我发现了另一个线程建议我增加了以下功能：

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

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

后做，所以我的代码现在：

class ShopViewController: UIPageViewController, UIPageViewControllerDataSource { 

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

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

    override func viewDidLoad() { 
    super.viewDidLoad() 

    } 

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

但我仍然得到一个错误说同样的+预期{在函数声明中我添加了2个新函数。

任何人都可以帮忙吗？

Answer 1

你需要使用这样的，因为你正在使用UIPageViewController，你是不执行委托方法viewControllerAfter和UIPageViewController这就是为什么你收到此错误viewControllerBefore。

class ShopViewController: UIPageViewController, UIPageViewControllerDataSource { 

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? { 
     // Returns the view controller after the given view controller. 
     return self 
    } 

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? { 
     // Returns the view controller before the given view controller. 

     return self 
    } 

    override func viewDidLoad() { 
     super.viewDidLoad() 

    } 

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