ios - 'NSRangeException'，原因 : '*** -[__NSArrayI objectAtIndex:]: index 3 beyond bounds [0 .. 2]'

Question

我尝试在 UIPageView 中显示三张图片，但每次滑动到第三张图片时，我都会收到此错误:'NSRangeException'，原因:'*** -[__NSArrayI objectAtIndex:]: 索引 3 超出范围 [0 .. 2]'

我已经检查了关于同一问题的其他问题，但无法弄清楚我的问题出在哪里。

这是输出的其余部分:

*** First throw call stack:
(
    0   CoreFoundation                      0x000000010a410c65 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x000000010a0a9bb7 objc_exception_throw + 45
    2   CoreFoundation                      0x000000010a30717e -[__NSArrayI objectAtIndex:] + 190
    3   BonBUp                              0x0000000109b1a1cb _TFC6BonBUp14ViewController21viewControllerAtIndexfS0_FSiCS_21ContentViewController + 619
    4   BonBUp                              0x0000000109b1a792 _TFC6BonBUp14ViewController18pageViewControllerfS0_FTCSo20UIPageViewController33viewControllerAfterViewControllerCSo16UIViewController_GSqS2__ + 418
    5   BonBUp                              0x0000000109b1a84f _TToFC6BonBUp14ViewController18pageViewControllerfS0_FTCSo20UIPageViewController33viewControllerAfterViewControllerCSo16UIViewController_GSqS2__ + 79
    6   UIKit                               0x000000010afc2c67 -[UIPageViewController _queuingScrollView:viewBefore:view:] + 129
    7   UIKit                               0x000000010b06044c -[_UIQueuingScrollView _viewAtIndex:loadingIfNecessary:updatingContents:animated:] + 247
    8   UIKit                               0x000000010b0625c2 -[_UIQueuingScrollView _adjustContentInsets] + 316
    9   UIKit                               0x000000010b060135 -[_UIQueuingScrollView _replaceViews:updatingContents:adjustContentInsets:animated:] + 763
    10  UIKit                               0x000000010b063287 -[_UIQueuingScrollView _didScrollWithAnimation:force:] + 1082
    11  UIKit                               0x000000010b05f42b -[_UIQueuingScrollView layoutSubviews] + 155
    12  UIKit                               0x000000010aacb9eb -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 536
    13  QuartzCore                          0x000000010f122ed2 -[CALayer layoutSublayers] + 146
    14  QuartzCore                          0x000000010f1176e6 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 380
    15  QuartzCore                          0x000000010f117556 _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 24
    16  QuartzCore                          0x000000010f08386e _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 242
    17  QuartzCore                          0x000000010f084a22 _ZN2CA11Transaction6commitEv + 462
    18  QuartzCore                          0x000000010f146085 _ZN2CA7Display11DisplayLink14dispatch_itemsEyyy + 489
    19  CoreFoundation                      0x000000010a378174 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 20
    20  CoreFoundation                      0x000000010a377d35 __CFRunLoopDoTimer + 1045
    21  CoreFoundation                      0x000000010a339d3d __CFRunLoopRun + 1901
    22  CoreFoundation                      0x000000010a339366 CFRunLoopRunSpecific + 470
    23  GraphicsServices                    0x000000010ec4ba3e GSEventRunModal + 161
    24  UIKit                               0x000000010aa4b8c0 UIApplicationMain + 1282
    25  BonBUp                              0x0000000109b21327 main + 135
    26  libdyld.dylib                       0x000000010cfe2145 start + 1
    27  ???                                 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

这是我的 ViewController 中的代码:

import UIKit

class ViewController: UIViewController, UIPageViewControllerDataSource {


    var pageViewController: UIPageViewController!
    var pageImages: NSArray!

    override func viewDidLoad() {
        super.viewDidLoad()

        self.pageImages = NSArray(objects: "jeans.png", "blusas.png", "leggings.png")

        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.pageViewController.view.frame = CGRectMake(0, 30, self.view.frame.width, self.view.frame.size.height - 60)

        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.
    }

    func viewControllerAtIndex(index: Int) -> ContentViewController
    {

        var vc: ContentViewController = self.storyboard?.instantiateViewControllerWithIdentifier("ContentViewController") as! ContentViewController

        vc.imageFile = self.pageImages[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++

        return self.viewControllerAtIndex(index)

    }

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


}

和ContentViewController:

import UIKit

class ContentViewController: UIViewController {

    @IBOutlet weak var imageView: UIImageView!
    var pageIndex: Int!
    var imageFile: String!



    override func viewDidLoad()
    {
        super.viewDidLoad()

        self.imageView.image = UIImage(named: self.imageFile)

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

}

Answer 1

您没有检查 index >= self.pageImages.count 是否在 viewControllerAtIndex 方法中返回 nil，所以当您在 last之后它会向 viewController 请求页面，你最终会因为索引越界而崩溃，你的方法应该如下所示。

 func viewControllerAtIndex(index: Int) -> ContentViewController?
    {
        if index >= self.pageImages.count
        {
            return nil
        }
        var vc: ContentViewController = self.storyboard?.instantiateViewControllerWithIdentifier("ContentViewController") as! ContentViewController

        vc.imageFile = self.pageImages[index] as! String
        vc.pageIndex = index

        return vc

    }

由于您的方法现在可以返回 nil，所以我在方法末尾添加了 ?，您现在需要对代码进行一些更改才能使用它。