我试图在我的iOS应用程序中制作一个教程屏幕,用户可以在屏幕上滑动几张图片来了解一下这个应用程序。一切看起来都很好,除了当我构建我的项目时,我在代码的第一行得到了以下错误:
类ViewController没有初始化器
我做错什么了?
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
}
}
发布于 2015-07-07 04:26:58
这是因为这一行:
var pageViewController: UIPageViewController
您的意思是pageViewController
不能为空,但是您没有将其设置为值的初始化器。查看您的代码,我怀疑您想要将其更改为:
var pageViewController: UIPageViewController!
发布于 2015-07-07 04:28:46
在Swift类中,每个非可选的声明变量都必须在给定的init方法中初始化。
在您的例子中,它是这个变量
var pageViewController: UIPageViewController
与其他两个变量一样,将其声明为隐式取消包装可选,因为可以保证在使用该变量之前对其进行设置。
var pageViewController: UIPageViewController!
https://stackoverflow.com/questions/31254941
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