Not able to update values of a dictionary in Swift

Question

I have a dictionary that I want to manipulate depending on options selcted by the user.

in the first View Controller:

var filterDictionary = [String : [String]]()

includes a function which is called from the second View Controller

func onOptionsCLosed(_ filter : String, options : [String]) {

    if options.count > 0 {
        print(filter)
        print(options)
        filterDictionary[filter] = options
        print(filterDictionary)
    }
}

and also an action that I'm using to test the result

@IBAction func submitFilter(_ sender: UIButton) {

    print(filterDictionary)

}

in the second View Controller, I have an action that checks the items in an array to make sure there something there and then passes the needed values to the first View Controller

 @IBAction func submitOptions(_ sender: UIButton) {
    let mainVC: FilterViewController = FilterViewController()
    var selectedOptions: [String]? = []

    if (optionCollectionView.indexPathsForSelectedItems != nil) {
        for i in optionCollectionView.indexPathsForSelectedItems! {
            let pos = i[1]
            selectedOptions?.append(options[pos])
        }

        mainVC.onOptionsCLosed(filter, options: selectedOptions!)
    } else {

        print("ELSE")
        // no items were selected prompt
    }

    _ = self.navigationController?.popViewController(animated: true)
}

The problem I'm running into is once the correct parameters are passed to the first View Controller and I'm able to print them out but if I click the button to check the values contained by the dictionary it prints and empty dictionary or rather it'll print: [:]

You are instantiating a new `FilterViewController`. That isn't the `FilterViewController` that you will be returning to. You should use delegation to pass back the data back to the calling viewController. — vacawama, Jul 20 '17 at 20:37
See MakeAppPie's answer: https://stackoverflow.com/q/24099230/1630618 — vacawama, Jul 20 '17 at 20:40

score 1 · Answer 1 · answered Jul 20 '17 at 20:39

The problem is that you're not passing the values to the first view controller. You're actually creating a third view controller in this line:

let mainVC: FilterViewController = FilterViewController()

You should grab a reference to the existing first view controller using self.presentingViewController or by setting a reference manually on SecondViewController before presenting.

Not able to update values of a dictionary in Swift

1 Answers1