我试图在我的 iOS 应用程序中制作一个教程屏幕，用户可以在其中滑动几张图片来了解有关该应用程序的一些信息。一切看起来都很好，除了当我构建项目时，我在第一行代码中收到以下错误：
ViewController 类没有初始化器
我做错了什么？
我的 ViewController.swift 代码如下
import UIKit
//line below is where I get the error
class ViewController: UIViewController, UIPageViewControllerDataSource {
//end
var pageViewController: UIPageViewController
var pageTitles: NSArray!
var pageImages: NSArray!
override func viewDidLoad() {
super.viewDidLoad()
self.pageTitles = NSArray(objects: "", "", "")
self.pageImages = NSArray(objects: "page1", "page2", "page3")
self.pageViewController = self.storyboard?.instantiateViewControllerWithIdentifier("PageViewController") as!
UIPageViewController
self.pageViewController.dataSource = self
var startVC = self.viewControllerAtIndex(0) as ContentViewController
var viewControllers = NSArray(object: startVC)
self.pageViewController.setViewControllers(viewControllers as [AnyObject], direction: .Forward, animated: true, completion: nil)
self.addChildViewController(self.pageViewController)
self.view.addSubview(self.pageViewController.view)
self.pageViewController.didMoveToParentViewController(self)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
@IBAction func restartAction(sender: AnyObject) {
}
func viewControllerAtIndex(index: Int) -> ContentViewController
{
if ((self.pageTitles.count == 0) || (index >= self.pageTitles.count))
{
return ContentViewController()
}
var vc: ContentViewController = self.storyboard?.instantiateViewControllerWithIdentifier("ContentViewController") as! ContentViewController
vc.imageFile = self.pageImages[index] as! String
vc.titleText = self.pageTitles[index] as! String
vc.pageIndex = index
return vc
}
// Mark: - Page View Controller Data Source
func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
var vc = viewController as! ContentViewController
var index = vc.pageIndex as Int
if (index == 0 || index == NSNotFound)
{
return nil
}
index--
return self.viewControllerAtIndex(index)
}
func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
var vc = viewController as! ContentViewController
var index = vc.pageIndex as Int
if (index == NSNotFound)
{
return nil
}
index++
if (index == self.pageTitles.count)
{
return nil
}
return self.viewControllerAtIndex(index)
}
func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int {
return self.pageTitles.count
}
func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {
return 0
}
}
这是因为这一行：
var pageViewController: UIPageViewController
你是这么说的pageViewController不能为 null，但您没有将其设置为值的初始值设定项。看看你的代码，我怀疑你想将其更改为：
var pageViewController: UIPageViewController!
我在这里更详细地讨论了这个问题。 https://www.hackingwithswift.com/example-code/language/fixing-class-viewcontroller-has-no-initializers
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