在swift2上管理页面导航

Question

I'm trying to learn page navigation without using "Navigation Controller".
Created a button and function like;

@IBAction func backPressed(sender: AnyObject) {
    self.performSegueWithIdentifier("page2ToMain", sender: self)
}

It works fine.
I need to pass data from page 2 to page 3. So, inside "didSelectRowAtIndexPath" I used "performSegueWithIdentifier" and override "prepareForSegue" function as below;

func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {

    self.selectedRow = self.dataArray[indexPath.row]

    self.performSegueWithIdentifier("page2ToPage3", sender: self)

}

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {

    let nextViewController = segue.destinationViewController as! ViewController3
    nextViewController.data = self.selectedRow
    print(self.selectedRow)

}

When I click the table cell it works well, jumps to other view controller and I see data variable.
But when I press back button it fails with;

 Could not cast value of type 'test3.ViewControllerMain' (0x1045469f0) to 'test3.ViewController3' (0x1045466e0).

How can I solve the problem?

Answer 1

You can test for this with optional binding:

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if let nextViewController = segue.destinationViewController as? ViewController3 {
        nextViewController.data = self.selectedRow
        print(self.selectedRow)
    }
}

Or look at the segue identifier and then test for that:

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if segue.identifier == "page2ToPage3" {
        let nextViewController = segue.destinationViewController as! ViewController3
        nextViewController.data = self.selectedRow
        print(self.selectedRow)
    }
}