Appending an Array in NSUserDefaults Swift

Question

So I want to append an array in the NSUserDefaults, not save an entirely new one. The issue is that I want the array to be a logged history of a certain type of user interaction so I need to be appending an existing array in the NSUserDefaults, and not overwriting it.

ie Not:

var data = [String]()
var questionsAsked = [String]()

func storeData() {

    let defaults = NSUserDefaults.standardUserDefaults()

    defaults.setObject(questionsAsked, forKey: "questionsAsked")
    defaults.setObject(data, forKey: "data")

    var storedQuestionsAsked = defaults.objectForKey("questionsAsked") as? [String] ?? [String]()

    var storedData = defaults.objectForKey("data") as? [String] ?? [String]()

}

The array(s) are based in my Modal, and the appending is occurring by appending that array in the ViewController of that Modal

I tried just calling a function like this, but this is just calling an empty array because its never being re-saved to the NSUserDefaults:

func updateQuestionsAsked(questionAsked: String, answerGiven: String) {

    let defaults = NSUserDefaults.standardUserDefaults()

    defaults.setObject([String](), forKey: "questionsAsked")
    defaults.setObject([String](), forKey: "data")

    var storedQuestionsAsked = defaults.objectForKey("questionsAsked") as? [String] ?? [String]()
    var storedData = defaults.objectForKey("data") as? [String] ?? [String]()

    storedData.append(questionAsked)
    storedQuestionsAsked.append(answerGiven)

    NSUserDefaults.standardUserDefaults().synchronize()
}

Is there some kind of synchronization thing I'm missing? I'm sure this is super simple but I'm just spacing out on what to do. Thanks!

Answer 1

YOu are setting empty data for keys "questionsAsked" & "data",

func updateQuestionsAsked(questionAsked: String, answerGiven: String) {

    let defaults = NSUserDefaults.standardUserDefaults()

    //remove this
    //defaults.setObject([String](), forKey: "questionsAsked")
    //defaults.setObject([String](), forKey: "data")

    var storedQuestionsAsked = defaults.objectForKey("questionsAsked") as? [String] ?? [String]()
    var storedData = defaults.objectForKey("data") as? [String] ?? [String]()

    storedData.append(questionAsked)
    storedQuestionsAsked.append(answerGiven)

    // then update whats in the `NSUserDefault`
    defaults.setObject(questionsAsked, forKey: "questionsAsked")
    defaults.setObject(data, forKey: "data")

    // call this after you update
    defaults.synchronize()
}

Another is maybe you failed to set object here...

func storeData() {

    let defaults = NSUserDefaults.standardUserDefaults()

    defaults.setObject(questionsAsked, forKey: "questionsAsked")
    defaults.setObject(data, forKey: "data")

    // call this after setting Objects
    //--
    defaults.synchronize()
    //--

    ...
}