Cant pass value to another viewController?

问题

I have some text in tableview cells which you will tap on it you will pass the name of the cell and also you will be pushed to another view.

       override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    tableView.deselectRow(at: indexPath as IndexPath, animated: true)

    let row = indexPath.row
    valueToPass = sections[row]
    print(valueToPass)
}


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

    if (segue.identifier == "fromWelcomeToSectionPage") {
        // initialize new view controller and cast it as your view controller
         let vc:sectionPage = segue.destination as! sectionPage
        vc.passedValue = valueToPass

    }
}

also I created code in another controller to check

    if passedValue == "Základy" {
        print("it works")
    }

This is how I trying to pass it. Variable valueToPass is global variable. Idk but when I'm printing it in didSelectRowAtIndexPath it's okey but in prepare it's nil.
After tapping on cell I've got unexpectedly found nil while unwrapping an Optional value

That's how I created variable in another view

var passedValue = String()

回答1:

Your prepareForSegue method is called before the didSelectRowAt method, so you can't rely on any logic you do in didSelectRow to help pass the data.

You can get the selected row in prepareForSegue and use it there to get the data and pass it along:

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

    if (segue.identifier == "fromWelcomeToSectionPage") {
         // initialize new view controller and cast it as your view controller
         let vc = segue.destination as! sectionPage
         let selectedRow = tableView.indexPathForSelectedRow!.row
         vc.passedValue = sections[selectedRow]
    }
}

来源：https://stackoverflow.com/questions/40113116/cant-pass-value-to-another-viewcontroller

标签

ios

swift

uitableview

segue