TableView loop through all cell for deleting them, Swift - ios

Question

I was trying iterating through all cell in TableView and delete them. I call function DeleteAll:
class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
#IBOutlet weak var myTableView: UITableView!
#IBAction func DeleteAll(sender: UIButton) {
//myTableView.reloadData()
for j in 0..<myTableView.numberOfSections {
for i in (myTableView.numberOfRowsInSection(j) - 1).stride(through: 0, by: -1) {
let myIndexPath = NSIndexPath(forRow: i, inSection: j)
print("I=" + String(i) + "section " + String(j))
self.tableView( myTableView, commitEditingStyle: UITableViewCellEditingStyle.Delete, forRowAtIndexPath: myIndexPath)
}
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
var indexPathForSelectedRows = [NSIndexPath]()
lazy var productLines: [ProductLine] = {
return ProductLine.productLines()
}()
func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
let selctedRow = tableView.cellForRowAtIndexPath(indexPath)!
if editingStyle == UITableViewCellEditingStyle.Delete {
productLines[indexPath.section].products.removeAtIndex(indexPath.row)
tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Automatic)
selctedRow.accessoryType = UITableViewCellAccessoryType.None
}
}
func tableView(tableView: UITableView, editActionsForRowAtIndexPath indexPath: NSIndexPath) -> [UITableViewRowAction]? {
let delete = UITableViewRowAction(style: .Destructive, title: "Delete") { (action, indexPath) in
self.tableView( tableView, commitEditingStyle: UITableViewCellEditingStyle.Delete, forRowAtIndexPath: indexPath)
}
let share = UITableViewRowAction(style: .Normal, title: "Disable") { (action, indexPath) in
}
delete.backgroundColor = UIColor.blackColor()
share.backgroundColor = UIColor.blueColor()
return [delete, share]
}
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
//self.tableView( tableView, commitEditingStyle: UITableViewCellEditingStyle.Delete, forRowAtIndexPath: indexPath)
let row = tableView.cellForRowAtIndexPath(indexPath)!
if row.accessoryType == UITableViewCellAccessoryType.None {
row.accessoryType = UITableViewCellAccessoryType.Checkmark
}
else {
row.accessoryType = UITableViewCellAccessoryType.None
}
}
// MARK: - Table view data source
func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
let productLine = productLines[section]
return productLine.name
}
//override func tableV
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
// #warning Incomplete implementation, return the number of sections
return productLines.count
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// #warning Incomplete implementation, return the number of rows
let productLine = productLines[section]
return productLine.products.count
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("uppercaseString", forIndexPath: indexPath)
let productLine = productLines[indexPath.section]
let product = productLine.products[indexPath.row]
cell.textLabel?.text = product.title
cell.detailTextLabel?.text = product.description
cell.imageView?.image = product.image
// Configure the cell...
return cell
}
}
But I have had this error, and I don't find out what wrong. This is console log:
I=3section 0
I=2section 0
I=1section 0
I=0section 0
I=8section 1
fatal error: unexpectedly found nil while unwrapping an Optional
value (lldb)

Answer 1

Yes, that will return nil if the row isn't on screen, so force
unwrapping is a bad idea. In fact calling the delegate methods
yourself is a bad idea. If you want to reuse code then you should have
your delegate method calla delete method. You can't retrieve all
cells; you can only retrieve cells that are onscreen. You shouldn't
need to retrieve all cells; you simply update your data model and have
the table reflect those changes by reloading the table, reloading
specific rows or inserting/deleting specific rows
– Paulw11