Passing object with prepareForSegue Swift

Question

I am trying to pass an object to another scene with prepareForSegue()

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        // Get the new view controller using [segue destinationViewController].
        var nextScene =  segue.destinationViewController as! VehicleDetailsTableViewController

        // Pass the selected object to the new view controller.
        if let indexPath = self.tableView.indexPathForSelectedRow() {
            let selectedVehicle = vehicles[indexPath.row]
            nextScene.currentVehicle = selectedVehicle
        }
    }

And I have currentVehicle object to catch these object. But, when I try to run, it brokes and get error about downcasting.

Error EDIT

Could not cast value of type 'XXX.DisplayViewController' (0x1082dcd80) to 'XXX.VehicleDetailsTableViewController' (0x1082dc9a0). (lldb)

Answer 1

You have to give the segue an identifier in the storyboard.(say mySegue)

Using Xcode 10 swift 4.x(Also works with Xcode 9 & 8 , swift 3.x)

override func prepare(for segue: UIStoryboardSegue, sender: Any?){}

Is called for all segues being called from your current UIViewController. So the identifier is to differentiate the different segues

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "mySegue" , 
       let nextScene = segue.destination as? VehicleDetailsTableViewController , 
       let indexPath = self.tableView.indexPathForSelectedRow {
        let selectedVehicle = vehicles[indexPath.row]
        nextScene.currentVehicle = selectedVehicle
    }
}

If you are using Using Xcode 7, swift 2.x

Then use this code:

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if segue.identifier == "mySegue" {
    var nextScene =  segue.destinationViewController as! VehicleDetailsTableViewController

    // Pass the selected object to the new view controller.
    if let indexPath = self.tableView.indexPathForSelectedRow {
        let selectedVehicle = vehicles[indexPath.row]
        nextScene.currentVehicle = selectedVehicle
    }
  }
}

Place a breakpoint after nextScene and see if it is being triggered by clicking any cell in the TableView. If it isn't then the identifier name u provided in the storyboard must be different then the one given here.

Answer 2

In swift 3.0 Xcode 8 beta 6

AnyObject has been renamed to Any?

override func prepare(for segue: UIStoryboardSegue, sender: Any?){
    let nextScene =  segue.destinationViewController as! VehicleDetailsTableViewController

    // Pass the selected object to the new view controller.
    if let indexPath = self.tableView.indexPathForSelectedRow {
        let selectedVehicle = vehicles[indexPath.row]
        nextScene.currentVehicle = selectedVehicle
    }
  }
}