UICollectionView sizeForItemAt IndexPath

Question

我试图为我的手机设定大小，根据里面的内容，这是我的代码，它崩溃了，我找不到错误的介面。

extension TimelineCollectionVC: UICollectionViewDelegateFlowLayout {



func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "timeline", for: indexPath) as? Timeline

    cell?.textView.translatesAutoresizingMaskIntoConstraints = true
    cell?.textView.sizeToFit()



    if cell?.containerView.subviews.count == 0 {
        cell?.containerHeight.constant = 1
    } else {
        cell?.containerHeight.constant = (cell?.containerView.subviews.first?.frame.size.height) ?? 80
    }

    let cellHeight = (cell?.upperView.bounds.height)! + (cell?.textView.bounds.height)! + (cell?.containerView.bounds.height)! + (cell?.lowerView.bounds.height)!


    return CGSize(width: 375, height: cellHeight)



}

}

原因：‘-*NSCFString setSizeHasBeenSet:：未识别的选择器发送到实例0x610000076bc0’*第一次抛出调用堆栈：(0 CoreFoundation 0x0000000109dd9d4b __exceptionPreprocess + 171 1 libobjc.A.dylib 0x00000001094d921e objc_exception_throw + 48 2 CoreFoundation 0x0000000109e49f04 -NSObject(NSObject) doesNotRecognizeSelector：+ 132 3 CoreFoundation 0x00000109d5f005 __ __)_forwarding_ + 1013 4 CoreFoundation 0x0000000109d5eb88 _CF_forwarding_prep_0 + 120 5 UIKit 0x00000001080d9485 -UICollectionViewFlowLayout _getSizingInfosWithExistingSizingDictionary：+ 3691 6 UIKit 0x00000001080da97b -UICollectionViewFlowLayout _fetchItemsInfoForRect：+ 127 7 UIKit 0x00000001080d3504 -UICollectionViewFlowLayout prepareLayout + 273 8UIKit 0x00000001080f3d6c -UICollectionViewData _prepareToLoadData + 159 9 UIKit 0x00000001080f4618 -UICollectionViewData validateLayoutInRect：+ 57 10 UIKit 0x000000010809b6d4 -UICollectionView layoutSubviews + 232 11 UIKit 0x000000107817ab8 -UIView(CALayerDelegate) layoutSublayersOfLayer：+ 1237 12 QuartzCore_ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 366 14 QuartzCore 0x00000106fc12be _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 24 15 QuartzCore 0x0000000106f4f318 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 280 16 QuartzCore 0x0000000106f7c3ff _ZN2CA11Transaction6commitEv + 475 17 QuartzCore0x00000106f7cd6f _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 113 18 CoreFoundation 0x0000000109d7e267 CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION** + 23 19 CoreFoundation 0x0000000109d7e1d7 __CFRunLoopDoObservers + 391 20 CoreFoundation 0x0000000109d628a6 CFRunLoopRunSpecific + 454 21 UIKit 0x000000010774 _run _run+ 43422 UIKit 0x0000000107752c68 UIApplicationMain + 159 23 Moden 0x0000000104ab4fbf main + 111 24 libdyld.dylib 0x000000010ad4e68d start +1) libc++abi.dylib:以NSException (lldb)类型的未加例外终止

Answer 1

您不应该在这里使用dequeueReusableCell。这只是为了创建新的单元格。在本例中，您希望获得一个现有的单元格，并且可能在UICollectionView类中使用UICollectionView。