我想了解這個錯誤是什么意思？
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason:
'the view returned from -collectionView:viewForSupplementaryElementOfKind:atIndexPath: was not
retrieved by calling -dequeueReusableSupplementaryViewOfKind:withReuseIdentifier:forIndexPath:
for element kind 'UICollectionElementKindSectionHeader' at index path <NSIndexPath: 0x8aeb905cf5be0ed2>
{length = 2, path = 0 - 0}; supplementary view:
<UICollectionReusableView: 0x7f9236dc4ff0; frame = (0 0; 0 0); layer = <CALayer: 0x600001018620>>'
我正在為 UICollectionView 使用自定義標頭。我在加載視圖后立即崩潰。即使在呼叫 cellforrowatindexpath 并且問題不在于自定義標頭之前，也在于回傳 UICollectionReusableView()
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
if kind == UICollectionView.elementKindSectionHeader && indexPath.section == 2
{
return someCustomHeader
}
return UICollectionReusableView()
}
uj5u.com熱心網友回復：
您必須始終使用方法獲取部分標題dequeueReusableSupplementaryViewOfKind:withReuseIdentifier:forIndexPath:，在呼叫它之前您還必須注冊一個標題類。如果您只想顯示第三部分的標題，您必須collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int)通過給它們一個.zero大小來隱藏不需要的標題（您不能簡單地UICollectionReusableView為不需要的標題回傳一個實體）。
import UIKit
class CollectionViewController: UICollectionViewController {
private let headerId = "headerId"
override func viewDidLoad(){
super.viewDidLoad()
// Registers a header class
self.collectionView.register(YourClass.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: self.headerId) // Replace YourClass with the name of your header class
}
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
// This method must always call dequeueReusableSupplementaryView, even if section!=2
if kind == UICollectionView.elementKindSectionHeader{
return self.collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: self.headerId, for: indexPath)
}
return UICollectionReusableView()
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize{
// Shows only the header of the third section
return section == 2 ? desiredSize : .zero // Replace desiredSize with the size of the visible header
}
}
uj5u.com熱心網友回復：
當您使用自定義標頭時，您必須首先注冊標頭類。
collectionView.register(AppHeaderCollectionView.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: AppHeaderCollectionView.headerIdentifier)
之后要使用標題，您必須這樣做。
override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
let header = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: AppHeaderCollectionView.headerIdentifier, for: indexPath) as! AppHeaderCollectionView
return header
}
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