Question

我最近为我的应用程序实现了一个新视图，其中UICollectionView充当了要加载图像的网格：

class MemoriesView: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource{

@IBOutlet weak var images_collection: UICollectionView!

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

    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)
        self.navigationController?.navigationBarHidden = false
    }

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

    func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 12
    }

    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier("memory_image_1", forIndexPath: indexPath) as! CollectionViewController
        return cell
    }

}

现在这个类中的代码很可能是完全颠倒的，因为我必须遵循这个教程。所以这里没有个人主动。因此，当我试图进入这个视图时，可能会产生这个错误：

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<Certi.MemoriesView 0x7fb613f3c8d0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key imageCollectionView.'

*** First throw call stack:
(
    0   CoreFoundation                      0x000000010ee6ae65 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x000000010f2c7deb objc_exception_throw + 48
    2   CoreFoundation                      0x000000010ee6aaa9 -[NSException raise] + 9
    3   Foundation                          0x000000010cfb29bb -[NSObject(NSKeyValueCoding) setValue:forKey:] + 288
    4   UIKit                               0x000000010d98c320 -[UIViewController setValue:forKey:] + 88
    5   UIKit                               0x000000010dbbaf41 -[UIRuntimeOutletConnection connect] + 109
    6   CoreFoundation                      0x000000010edab4a0 -[NSArray makeObjectsPerformSelector:] + 224
    7   UIKit                               0x000000010dbb9924 -[UINib instantiateWithOwner:options:] + 1864
    8   UIKit                               0x000000010d992eea -[UIViewController _loadViewFromNibNamed:bundle:] + 381
    9   UIKit                               0x000000010d993816 -[UIViewController loadView] + 178
    10  UIKit                               0x000000010d993b74 -[UIViewController loadViewIfRequired] + 138
    11  UIKit                               0x000000010d999f4f -[UIViewController __viewWillAppear:] + 120
    12  UIKit                               0x000000010d9c9e44 -[UINavigationController _startCustomTransition:] + 1203
    13  UIKit                               0x000000010d9da23f -[UINavigationController _startDeferredTransitionIfNeeded:] + 712
    14  UIKit                               0x000000010d9db3af -[UINavigationController __viewWillLayoutSubviews] + 57
    15  UIKit                               0x000000010db81ff7 -[UILayoutContainerView layoutSubviews] + 248
    16  UIKit                               0x000000010d8b44a3 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 703
    17  QuartzCore                          0x000000011101459a -[CALayer layoutSublayers] + 146
    18  QuartzCore                          0x0000000111008e70 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 366
    19  QuartzCore                          0x0000000111008cee _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 24
    20  QuartzCore                          0x0000000110ffd475 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 277
    21  QuartzCore                          0x000000011102ac0a _ZN2CA11Transaction6commitEv + 486
    22  UIKit                               0x000000010d7f7f7c _UIApplicationHandleEventQueue + 7329
    23  CoreFoundation                      0x000000010ed96a31 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
    24  CoreFoundation                      0x000000010ed8c95c __CFRunLoopDoSources0 + 556
    25  CoreFoundation                      0x000000010ed8be13 __CFRunLoopRun + 867
    26  CoreFoundation                      0x000000010ed8b828 CFRunLoopRunSpecific + 488
    27  GraphicsServices                    0x00000001115d7ad2 GSEventRunModal + 161
    28  UIKit                               0x000000010d7fd610 UIApplicationMain + 171
    29  Certi                               0x000000010b92c1fd main + 109
    30  libdyld.dylib                       0x000000010fde392d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

Answer 1

此功能是问题所在：

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("memory_image_1", forIndexPath: indexPath) as! CollectionViewController

return cell

您正在尝试将UICollectionViewCell转换为CollectionViewController。对该行末尾的简单更改：

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("memory_image_1", forIndexPath: indexPath) as! UICollectionViewCell
// see below
return cell

会阻止此错误，但您仍会获得空白单元格。我添加评论\\ see below的位置是您需要更新cell的值以选择此行上显示的内容的位置。如果您使用多个部分，则可以从indexPath.row和indexPath.section确定该行。

此外，如果您正在为您的单元格使用自定义类来处理默认视图以外的视图，那么您需要将cell强制转换为该自定义类，而不是UICollectionViewController虽然我假设你还在看教程，但这不是你将要尝试的东西。

正如我在该问题的评论中所述，教程 - https://www.raywenderlich.com/136159/uicollectionview-tutorial-getting-started - 以及本网站上的其他教程对初学者非常有用。

Answer 2

我怀疑您确实已将IBOutlet imageCollectionView重命名为images_collection，但未在故事板中更新此内容。

解决此问题：

右键点击故事板中的imageCollectionView
点击小“x”按钮

Memories View

通过将代码中的IBOutlet拖至故事板中的imageCollectionView来创建新链接

NSUnknownKeyException UICollectionView

2 个答案: