UIAlert视图从CustomCell类// Swift触发

Question

I have a TableViewCell populated with CustomCells. In the customCells I have a button which I want to trigger an UIAlert.

Here is my code for the button in the CustomCell Class:

@IBAction func anzahlButton(sender: UIButton) {

    let alert = UIAlertController(title: "Bitte gib Deine gewünschte Anzahl an:", message: nil, preferredStyle: .Alert)
    alert.addTextFieldWithConfigurationHandler {
        (tf:UITextField!) in
        tf.keyboardType = .NumberPad
        tf.addTarget(self, action: "textChanged:", forControlEvents: .EditingChanged)
    }

    func handler(act:UIAlertAction!) {
        let tf = alert.textFields![0] as UITextField
        let addItem = "\(tf.text)"
        var fixedToDoItems = ""
        anzahlText.setTitle("\(addItem)", forState: .Normal)
        //println("User entered \(addItem), tapped \(act.title)")
    }

    alert.addAction(UIAlertAction(title: "Cancel", style: .Cancel, handler: nil))
    alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: handler))
    (alert.actions[1] as UIAlertAction).enabled = false

    TableViewController().presentViewController(alert, animated: true, completion: nil)
}

When I hit the button I get this alert: Warning: Attempt to present <UIAlertController: 0x7fc7f0cbc5c0> on <MyApp.TableViewController: 0x7fc7f0c965f0> whose view is not in the window hierarchy!

I deed some resaerch on the debug-alert, but couldn't find an answer that is in swift and works for me... ;-)

Any ideas?

THX //Seb

Answer 1

In your line TableViewController().presentViewController , TableViewController() actually creates a new instance of the view controller TableViewController . This instance is not the one currently displayed on the screen. Which is why you get the error that the view is not part of the window hierarchy.

In order to fix that move the func anzahlButton(sender: UIButton) to the TableViewController file and then connect it to the button through cellForRowAtIndexPath function. remove the @IBAction part since we are no longer connecting the button through the interface builder.

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell 
{
    // Your Code
    cell.button.addTarget(self, action: "anzahlButton:", forControlEvents: UIControlEvents.TouchUpInside)
}

Then change the line

TableViewController().presentViewController(alert, animated: true, completion: nil)

to

self.presentViewController(alert, animated: true, completion: nil)