Nsuserdefaults highscore saving - swift

Question

var score = 0
var highscore = 0
var defaults = NSUserDefaults.standardUserDefaults()
#IBOutlet weak var scoreResult: UILabel!
#IBOutlet weak var highScoreResult: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
if let hscore = defaults.valueForKey("highscore") {
highScoreResult.text = String(hscore)
}
}
#IBAction func tapPressed(sender: AnyObject) {
score++
scoreResult.text = String(score)
if score > highscore {
highscore = score
highScoreResult.text = String(highscore)
defaults.setValue(highscore, forKey: "highscore")
defaults.synchronize()
}
}
When i press "tapPressed" button, score++ , then it saves as highscore, the problem is that when i restart app and i have highscore saved. When i press "tapPressed" highscore starts from zero again.

Answer 1

Change viewDidLoad to:
override func viewDidLoad() {
super.viewDidLoad()
if let hscore = defaults.valueForKey("highscore") {
highscore = hscore
highScoreResult.text = String(hscore)
}
}
That should load the highscore from the defaults once you're app launches.

Answer 2

In your viewDidLoad you need to change your statement to this:
if let hscore = defaults.valueForKey("highscore") {
highscore = hscore
highScoreResult.text = String(hscore)
}

Answer 3

The other answers are describing the reason for the error. In addition I'd like to describe also to use NSUserDefaults properly.
The recommended way is to register the key/value pairs to have reliable default values in case the preference file will be deleted or the app launches the first time.
In AppDelegate (applicationDidFinishLaunching or earlier) register highscore with a value of 0.
let defaultValues = ["highscore" : 0]
defaults.registerDefaults(defaultValues)
Then in viewDidLoad just write
let highscore = defaults.integerForKey("highscore")
highScoreResult.text = String(highscore)
There is no optional binding needed because the value in user defaults is always a non optional.
To save highscore back to disk use the dedicated method setInteger:forKey:
defaults.setInteger(highscore, forKey: "highscore")
valueForKey: is a KVC method with a special meaning and should not be used with NSUserDefaults.