如何更改尚未顯示在屏幕上的單元格的屬性？

我有一個應用程序，它包含一個時間表（UITableView）和一個白天（UICollectionView）。用戶可以通過以下兩種方法之一改變自己選定日期：如何更改尚未顯示在屏幕上的單元格的屬性？

從DayBar
選擇一天點擊「JumpToTomorrow」按鈕，表格視圖的底部。

現在的問題是，當我在第二天尚未滾動到屏幕上的場景中單擊它時，未選擇當天的單元格（請參閱下文）。

DayCollectionViewCell.isSelected（不會被調用由於某種原因）

override var isSelected: Bool { 
    didSet { 
     self.backgroundColor  = self.getBackgroundColor(selected: isSelected) 
     self.layer.borderColor  = self.getBorderColor(selected: isSelected) 
     self.number.attributedText = NSAttributedString(string: number.text!, attributes: self.getTextAttributes(selected: isSelected)) 
    } 
}

DayBarController功能

override func viewDidLoad() { 
    super.viewDidLoad() 
    // To preserve selection between presentations 
    self.clearsSelectionOnViewWillAppear = false 
    setEdgeInsets() 
    BroadcastManager.listen(to: PrepNotifications.JumpToTomorrowClicked, listenerId: "UpdateSelectedDay", react: updateSelectedDay) 
} 
    /// change the selected day and notify the app about the change 
override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) { 
    PrepGlobals.Calendar.SELECTED_DAY = indexPath.row 
    BroadcastManager.broadcast(PrepNotifications.SelectedDayChanged) 
    //scroll to center on selected day in case of clicked on today 
    if (PrepGlobals.Calendar.TODAY_INDEX == indexPath.row){ 
     self.collectionView?.scrollToItem(
      at: indexPath, 
      at: .centeredHorizontally, 
      animated: true 
     ) 
    } 
} 

private func updateSelectedDay(_ userInfo: [AnyHashable: Any]? = nil) { 
    PrepGlobals.Calendar.SELECTED_DAY += 1 
    let selectedDayIndex = IndexPath(row: PrepGlobals.Calendar.SELECTED_DAY, section: 0) 
    self.collectionView!.selectItem(at: selectedDayIndex, animated: true, scrollPosition: .right) 
    BroadcastManager.broadcast(PrepNotifications.SelectedDayChanged) 
}

來源

2017-06-01 Deco

我編輯了我的答案。其實你必須手動設置isSelected。

override func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) { 
     cell.isSelected = (indexPath.row == PrepGlobals.Calendar.SELECTED_DAY) 
}

來源

2017-06-01 09:35:45 PMT

這也適用。 – Deco