Swift --- PageViewController 封装循

准备工作 用storyboard 创建一个pageviewController 和 3个 controller 我之前文章有说过创建方法pageviewController传送门

本章只讲封装pageviewController
话不多说，开撸

创建一个继承pageviewController的类

 import UIKit

class TutorialPageViewController: UIPageViewController {

weak var tutorialDelegate: TutorialPageViewControllerDelegate?

fileprivate(set) lazy var orderedViewControllers: [UIViewController] = {
    // The view controllers will be shown in this order
    return [self.newColoredViewController("Green"),
            self.newColoredViewController("Red"),
            self.newColoredViewController("Blue")]
}()

override func viewDidLoad() {
    super.viewDidLoad()
    
    dataSource = self
    delegate = self
    
    
    if let initialViewController = orderedViewControllers.first {
        scrollToViewController(initialViewController, anima: true)
    }
    
    tutorialDelegate?.tutorialPageViewController(self,
                                                 didUpdatePageCount: orderedViewControllers.count)
}

/**
 Scrolls to the next view controller.
 */
func scrollToNextViewController() {
    if let visibleViewController = viewControllers?.first,
        let nextViewController = pageViewController(self,
                                                    viewControllerAfter: visibleViewController) {
        scrollToViewController(nextViewController, anima: true)
    }
}

/**
 Scrolls to the view controller at the given index. Automatically calculates
 the direction.
 
 - parameter newIndex: the new index to scroll to
 */
func scrollToViewController(index newIndex: Int,animal:Bool) {
    if let firstViewController = viewControllers?.first,
        let currentIndex = orderedViewControllers.index(of: firstViewController) {
        let direction: UIPageViewControllerNavigationDirection = newIndex >= currentIndex ? .forward : .reverse
        let nextViewController = orderedViewControllers[newIndex]
        scrollToViewController(nextViewController, direction: direction,anima:animal)
    }
}

fileprivate func newColoredViewController(_ color: String) -> UIViewController {
    return UIStoryboard(name: "Main", bundle: nil) .
        instantiateViewController(withIdentifier: "\(color)ViewController")
}

/**
 Scrolls to the given 'viewController' page.
 
 - parameter viewController: the view controller to show.
 */
fileprivate func scrollToViewController(_ viewController: UIViewController,
                                        direction: UIPageViewControllerNavigationDirection = .forward,anima:Bool) {
    setViewControllers([viewController],
                       direction: direction,
                       animated: anima,
                       completion: { (finished) -> Void in
                        // Setting the view controller programmatically does not fire
                        // any delegate methods, so we have to manually notify the
                        // 'tutorialDelegate' of the new index.
                        self.notifyTutorialDelegateOfNewIndex()
    })
}

/**
 Notifies '_tutorialDelegate' that the current page index was updated.
 */
fileprivate func notifyTutorialDelegateOfNewIndex() {
    if let firstViewController = viewControllers?.first,
        let index = orderedViewControllers.index(of: firstViewController) {
        tutorialDelegate?.tutorialPageViewController(self,
                                                     didUpdatePageIndex: index)
    }
}

 }

 // MARK: UIPageViewControllerDataSource

 extension TutorialPageViewController: UIPageViewControllerDataSource {

func pageViewController(_ pageViewController: UIPageViewController,
                        viewControllerBefore viewController: UIViewController) -> UIViewController? {
    guard let viewControllerIndex = orderedViewControllers.index(of: viewController) else {
        return nil
    }
    
    let previousIndex = viewControllerIndex - 1
    
    // User is on the first view controller and swiped left to loop to
    // the last view controller.
    guard previousIndex >= 0 else {
        return orderedViewControllers.last
    }
    
    guard orderedViewControllers.count > previousIndex else {
        return nil
    }
    
    return orderedViewControllers[previousIndex]
}

func pageViewController(_ pageViewController: UIPageViewController,
                        viewControllerAfter viewController: UIViewController) -> UIViewController? {
    guard let viewControllerIndex = orderedViewControllers.index(of: viewController) else {
        return nil
    }
    
    let nextIndex = viewControllerIndex + 1
    let orderedViewControllersCount = orderedViewControllers.count
    
    // User is on the last view controller and swiped right to loop to
    // the first view controller.
    guard orderedViewControllersCount != nextIndex else {
        return orderedViewControllers.first
    }
    
    guard orderedViewControllersCount > nextIndex else {
        return nil
    }
    
    return orderedViewControllers[nextIndex]
}

 }

extension TutorialPageViewController: UIPageViewControllerDelegate {

func pageViewController(_ pageViewController: UIPageViewController,
                        didFinishAnimating finished: Bool,
                        previousViewControllers: [UIViewController],
                        transitionCompleted completed: Bool) {
    notifyTutorialDelegateOfNewIndex()
}

}

 protocol TutorialPageViewControllerDelegate: class {

/**
 Called when the number of pages is updated.
 
 - parameter tutorialPageViewController: the TutorialPageViewController instance
 - parameter count: the total number of pages.
 */
func tutorialPageViewController(_ tutorialPageViewController: TutorialPageViewController,
                                didUpdatePageCount count: Int)

/**
 Called when the current index is updated.
 
 - parameter tutorialPageViewController: the TutorialPageViewController instance
 - parameter index: the index of the currently visible page.
 */
func tutorialPageViewController(_ tutorialPageViewController: TutorialPageViewController,
                                didUpdatePageIndex index: Int)

}

在主Controller中实现代理方法

 var tutorialPageViewController: TutorialPageViewController? {
    didSet {
        tutorialPageViewController?.tutorialDelegate = self
    }
}

func tutorialPageViewController(_ tutorialPageViewController: TutorialPageViewController,
                                didUpdatePageCount count: Int) {
 }

func tutorialPageViewController(_ tutorialPageViewController: TutorialPageViewController,
                                didUpdatePageIndex index: Int) {
    
    print(index)
 }


override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if let tutorialPageViewController = segue.destination as? TutorialPageViewController {
        self.tutorialPageViewController = tutorialPageViewController
    }
}

demo地址