I'm new in swift and I need help with deleting colleciton view cell. In this code, if indexPath is 0, i have error with deleting that cell.

 @IBAction func deleteItem(_ sender: Any) {
    
    if let selectedCells = tablesCollectionView.indexPathsForSelectedItems{
        let items = selectedCells.map {$0.item}.sorted().reversed()
        

        for item in items {
            tables.remove(at: item)
            let tableNo: TableModel
            tableNo = tables[item-1]  //Thread 1: Fatal error: Index out of range
            
            refTables = Database.database().reference().child("userInfo").child(uid!).child("tables")
            refTables.child(tableNo.id!).removeValue { error,arg  in
               if error != nil {
                   print("error \(error)")
               }
             }
            
        }
      
        tablesCollectionView.deleteItems(at: selectedCells)
        deleteButton.isEnabled = false
    }
    
}

I have this message "Thread 1: Fatal error: Index out of range" when I try to delete the cell with 0 indexPath.

CodePudding user response：

This line

tables.remove(at: item)

Is dangerous inside a for loop , as while you delete from array it's size changes which make old indices goes wrong

You need

var toDeleteIds = [String]()
for item in items {
  let tableNo = tables[item]  
  toDeleteIds.append(tableNo.id!)
  refTables =  Database.database().reference().child("userInfo").child(uid!).child("tables")
  refTables.child(tableNo.id!).removeValue { error,arg  in
    if error != nil {
      print("error \(error)")
    }
  } 
} 
tables.removeAll { toDeleteIds.contains($0.id) }