Values replacing each other using UserDefaults - ios

Question

I have an app where I time myself and see how long it takes me to complete a bunch of questions. I have the time transferred to another VC and displayed in a label. I have it being stored by pressing a button but when i have a new variable(time) it replaces it. How do i store an Array of values and that can be displayed in a label?
Button to save the value:
#IBAction func saveScore(_ sender: Any) {
scoreLabel.text = label.text
UserDefaults.standard.set(scoreLabel.text, forKey: "score")
}
The code that permanently holds the data:
override func viewDidAppear(_ animated: Bool) {
if let x = UserDefaults.standard.object(forKey: "score") as? String {
scoreLabel.text = x
}
}
My scoreLabel displays all my scores and label shows the time you just got.

Answer 1

Use the following extentions on UserDefaults to store an array of times:
extension UserDefaults {
var times: [String] {
get {
if let times = UserDefaults.standard.object(forKey: "times") as? [String] {
return times
} else {
return []
}
}
set {
UserDefaults.standard.set(newValue, forKey: "times")
}
}
}
While you don't need to extend UserDefaults, using extension can simplify a bit working with persisted values and it makes the code cleaner.
Then at the point where you show the data, use the following line to access the array:
let arrayOfTimes = UserDefaults.standard.times
scoreLabel.text = "\(arrayOfTimes)" // or any other formatting you'd like
And instead of setting the times to persist a new score, just add the new score to the array, e.g.:
// This will not only add the scoreLabel.text to the array, but also persists it
UserDefaults.standard.times.append(scoreLabel.text)

Answer 2

In Swift 4,
To save an array to User Defaults you would do:
let defaults = UserDefaults.standard
let array = [25, 50]
defaults.set(array, forKey: "Scores")
And to access the array from User Defaults:
let defaults = UserDefaults.standard
let retrievedArray = defaults.array(forKey: "Scores") as? [Int] ?? []
And if you were to display a score of your array in a label then, you would just do:
scoreLabel.text = String(describing: retrievedArray[0])
If you are using integers for your scoring system, I would suggest you
storing your scores as Int in User Defaults.
If you prefer using Strings though, please note that you can use the User Defaults' stringArray(forKey:) method directly, instead of the array(forKey:) method, and therefore, in that case, you wouldn't need to type cast your array:
let someStringArray = defaults.stringArray(forKey: "ArrayOfStrings")
Note: To answer your question, I will consider that you are using Int scores, but feel free to use whichever you prefer.
If you want to store your array to the same key in User Defaults every time you get a new score, you could do it easily like this:
let defaults = UserDefaults.standard
// Your new score:
let newScore = 75
// Get your current scores list from User Defaults:
var currentArray = defaults.array(forKey: "Scores") as? [Int] ?? []
// Append your new score to the current array:
let updatedArray = currentArray.append(newScore)
// And save your updated array to User Defaults:
defaults.set(updatedArray, forKey: "Scores")
// In this example, your User Defaults now contains the updated array [25, 50, 75]
And that's it :).
Please note that there is no need to use an extension for that..
UPDATE: Also, if you want to add something inside your viewDidAppear method, don't forget to add super.viewDidAppear(animated). The same goes for viewDidLoad, etc.
The documentation states:
You can override this method to perform additional tasks associated
with presenting the view. If you override this method, you must call
super at some point in your implementation.
So you would have:
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
if let retrievedArray = defaults.array(forKey: "Scores") as? [Int] {
print(retrievedArray)
// You can access your scores array safely here
}
}