How to add a segue programmatically?

Question

I know, I know this has been asked a lot of times. I also found this question but the solution it suggested did not work for me.

I am just trying to build an app to demonstrate how to use those things in UIKit (in case I want to use them later on. I can just copy the code).

I have created a View Controller with a table view in it. I wrote a class called PrototypeTableController to act as the view controller class for the view controller I created in the storyboard.

When the user taps on one of the cells, I want another view controller to show, called Prototype Table Content. And different text will be shown if you tap on different cells.

In the storyboard, it's like this:

The text of the label in Prototype Table Content will be different when the user taps on a different cell. This means I need to send data from one view controller to another.

The post mentioned above suggested that I should give the segue an identifier, so I did:

Here is my code:

View controller class for the table view:

class PrototypeTableController: UIViewController, UITableViewDataSource, UITableViewDelegate {
    let data = ["Cell1", "Cell2", "Cell3", "Cell4", "Cell5"]
    let contents = ["Hello", "Nice", "OMG", "Jesus", "Peace"]
    var content: String?

    func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        return 1
    }

    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return data.count
    }

    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = UITableViewCell()
        cell.textLabel?.text = data[indexPath.row]
        return cell
    }

    func tableView(tableView: UITableView, titleForFooterInSection section: Int) -> String? {
        return "This is a prototype table view created by Sweeper"
    }

    func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
        return "my table"
    }

    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
        content = contents[indexPath.row]
        tableView.deselectRowAtIndexPath(indexPath, animated: true)
        performSegueWithIdentifier("showContent", sender: tableView)
    }

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if segue.identifier == "showContent" {
            let destination = segue.destinationViewController as! PrototypeTableContentViewController
            destination.contentString = content
        }
    }
}

View controller class for Prototype Table Content view:

class PrototypeTableContentViewController: UIViewController {
    @IBOutlet var tableContent: UILabel!
    var contentString: String?

    override func viewDidLoad() {
        super.viewDidLoad()
        tableContent.text = contentString
    }
}

I think I did all the things suggested in the post mentioned above. I added an identifier, I called performSegueWithIdentifier , I also deselected the cell after the tapping.

However, it just doesn't go to the other view controller! It stays on the same controller! Like this:

push view controller instead of adding segue programmatically — Divyanshu Sharma, Dec 28 '15 at 14:05
push doesn't happen, when table doesn't have navigation controller @DivyanshuSharma — Teja Nandamuri, Dec 28 '15 at 14:06
Try this if segue!.identifier == or if( segue.identifier == ) — Teja Nandamuri, Dec 28 '15 at 14:12
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/99136/discussion-between-mr-t-and-sweeper). — Teja Nandamuri, Dec 28 '15 at 14:16
Can you try this 'segue.identifier! == "showContent"' instead of 'segue.identifier == "showContent" ' . identifier is an optional and it requires unwrapping. Tell me if that works — LearneriOS, Dec 28 '15 at 14:16

score 4 · Answer 1 · edited Sep 27 '17 at 21:10

When the user taps on one of the cells, I want another view controller to show, called Prototype Table Content. And different text will be shown if you tap on different cells.

While you can programmatically call performSegueWithIdentifier, it's a lot of effort that the storyboard can automatically handle for you. Just use a show storyboard segue from your prototype cell to PrototypeTableContentViewController.

prepareForSegue knows which cell you selected because the cell is the sender. All you have to do is set the destination view controller's contentString.

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    guard let controller = (segue.destinationViewController as? PrototypeTableContentViewController where segue.identifier == "showContent", let cell = sender as? UITableViewCell, textLabel = cell.textLabel else {
        return
    }

    controller.contentString = textLabel.text
}

This is very similar to how a template like Master-Detail segues from a cell to show details about a cell (although Apple uses indexPathForSelectedRow to pass the cell's details):

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if segue.identifier == "showDetail" {
        if let indexPath = self.tableView.indexPathForSelectedRow {
            let object = objects[indexPath.row] as! NSDate
            let controller = (segue.destinationViewController as! UINavigationController).topViewController as! DetailViewController
            controller.detailItem = object
            controller.navigationItem.leftBarButtonItem = self.splitViewController?.displayModeButtonItem()
            controller.navigationItem.leftItemsSupplementBackButton = true
        }
    }
}

In either case, the SDK performs the storyboard segue for you; a segue didn't need to be programmatically added or performed.

score 3 · Accepted Answer · answered Dec 28 '15 at 14:21

Make sure your tableview delegate is set. If you are using storyboard, make sure delegate outlet in your storyboard is connected properly. If you are creating tableview by code, then you should do tableView.delegate=self; to set the delegate.

Your code is fine.

And one more thing:

You might need to change this line:

     performSegueWithIdentifier("showContent", sender: tableView)

you need to make the sender as the row but not the tableview,so that the prepare for segue will get the sender as row instead of whole tableview.

As you are calling the prepareForSegue overtime you select a row, it makes sense to make the row as sender in performSegueWithIdentifier.

So it would be:

            let row=indexPAth.row
          performSegueWithIdentifier("showContent", sender: row)

How to add a segue programmatically?

2 Answers2