Question

我正在编写一个Swift应用程序，使用Parse，我得到一个奇怪的＆＃34; unrecognized selector sent to instance＆＃34;错误。首先，它只发生在我在iPhone 5（iPhone 5模拟器或iPhone 5c，我用于开发）上的应用程序上。其次，抛出错误的选择器实际上是属性，而不是方法。我尝试使用Instruments运行应用程序来搜索已解除分配的对象，但无法找到任何问题 - 对象似乎是正确的类型（自定义类Image）。

错误在以下方法中引发，罪魁祸首是isTextOnPicture属性。

func prepareCell(image: Image) {
    translatedText.frame = CGRectMake(translatedText.frame.origin.x,
                                      image.isTextOnPicture ? originalText.frame.origin.y + originalText.frame.height : originalText.frame.origin.y,
                                      translatedText.frame.width,
                                      translatedText.frame.height)
    originalText.hidden = image.isTextOnPicture
    translatedText.hidden = true
    bottomBarView.hidden = true
    saveButton.hidden = true
    translateButton.hidden = true
    shareButton.hidden = true
    translationSearchBar.hidden = true
    translationSearchBar.text = ""
}

我的cellForItemAtIndexPath中的UICollectionViewController方法会调用此方法。这是Image-class：

class Image: PFObject, PFSubclassing {

    @NSManaged var isTextOnPicture: Bool
    @NSManaged var translations: [String: String]!
    @NSManaged var tags: [String]!
    @NSManaged var name: String!
    @NSManaged var image: PFFile!
    @NSManaged var textLanguage: Language!

    override class func initialize() {
        var onceToken : dispatch_once_t = 0;
        dispatch_once(&onceToken) {
            self.registerSubclass()
        }
    }

    class func parseClassName() -> String {
        return "Image"
    }
}

编辑：

这是实际的错误消息：

2015-04-20 15:55:02.673 LesDudesApp[2592:52255] -[LesDudesApp.Image isTextOnPicture]: unrecognized selector sent to instance 0x7b60bda0
2015-04-20 15:55:02.690 LesDudesApp[2592:52255] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[LesDudesApp.Image isTextOnPicture]: unrecognized selector sent to instance 0x7b60bda0'
*** First throw call stack:
(
    0   CoreFoundation                      0x0106c746 __exceptionPreprocess + 182
    1   libobjc.A.dylib                     0x02fefa97 objc_exception_throw + 44
    2   CoreFoundation                      0x01074705 -[NSObject(NSObject) doesNotRecognizeSelector:] + 277
    3   CoreFoundation                      0x00fbb287 ___forwarding___ + 1047
    4   CoreFoundation                      0x00fbae4e _CF_forwarding_prep_0 + 14
    5   LesDudesApp                         0x000db4d6 _TFC11LesDudesApp16FunnyPictureCell11prepareCellfS0_FCS_5ImageT_ + 486
    6   LesDudesApp                         0x000bbd71 _TFC11LesDudesApp36FunnyPictureCollectionViewController14collectionViewfS0_FTCSo16UICollectionView22cellForItemAtIndexPathCSo11NSIndexPath_CSo20UICollectionViewCell + 737
    7   LesDudesApp                         0x000bd929 _TToFC11LesDudesApp36FunnyPictureCollectionViewController14collectionViewfS0_FTCSo16UICollectionView22cellForItemAtIndexPathCSo11NSIndexPath_CSo20UICollectionViewCell + 89
    8   UIKit                               0x0251fd5a -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:applyAttributes:] + 258
    9   UIKit                               0x02521e96 -[UICollectionView _updateVisibleCellsNow:] + 4947
    10  UIKit                               0x025266e1 -[UICollectionView layoutSubviews] + 281
    11  UIKit                               0x01ea557a -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 668
    12  libobjc.A.dylib                     0x03005771 -[NSObject performSelector:withObject:] + 70
    13  QuartzCore                          0x01c35e47 -[CALayer layoutSublayers] + 144
    14  QuartzCore                          0x01c29925 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 403
    15  QuartzCore                          0x01c2977a _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 26
    16  QuartzCore                          0x01b85c52 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 284
    17  QuartzCore                          0x01b870e5 _ZN2CA11Transaction6commitEv + 487
    18  QuartzCore                          0x01b877fc _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 92
    19  CoreFoundation                      0x00f8d86e __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 30
    20  CoreFoundation                      0x00f8d7b0 __CFRunLoopDoObservers + 400
    21  CoreFoundation                      0x00f831ea __CFRunLoopRun + 1226
    22  CoreFoundation                      0x00f82a5b CFRunLoopRunSpecific + 443
    23  CoreFoundation                      0x00f8288b CFRunLoopRunInMode + 123
    24  GraphicsServices                    0x082632c9 GSEventRunModal + 192
    25  GraphicsServices                    0x08263106 GSEventRun + 104
    26  UIKit                               0x01e12106 UIApplicationMain + 1526
    27  LesDudesApp                         0x000b13b4 main + 180
    28  libdyld.dylib                       0x07259ac9 start + 1
    29  ???                                 0x00000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

堆栈跟踪：

enter image description here

cellForRowAtIndexPath方法：

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {

    let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! FunnyPictureCell
    let currentImage = self.images[indexPath.row] as Image
    cell.image = currentImage
    cell.delegate = self

    cell.prepareCell(currentImage)

    if indexPath.row == 0 {
        User.currentUser()!.statistics.totalPicsViewed++
        AppDelegate.getInstance().picsForSession++
    }

    currentImage.image.getDataInBackgroundWithBlock { (data: NSData?, error: NSError?) -> Void in
        if error == nil && data != nil {
            cell.funnyPictureImageView.image = UIImage(data: data!)
        } else {
            println ("error while loading image: \(error)")
        }
    }

    cell.originalText.text = currentImage.translations[User.currentUser()!.motherTongue.language.lowercaseString]
    cell.translatedText.text = currentImage.translations[User.currentUser()!.learningLanguage.language.lowercaseString]

    return cell
}

Answer 1

你确定isTextOnPicture在落入该函数时有一个值吗？

Optionals在有值时不再隐式评估为true，否则不再隐式评估为false，以避免在使用可选的Bool值时出现混淆。相反，使用==或！=运算符对nil进行显式检查，以确定可选项是否包含值。

无法识别的选择器发送到属性的实例

1 个答案: