Testing And Loading A High Score In Swift - ios

Question

When I try to load my high score and see if the score I just got was bigger, I am getting some problems. First it seems to be adding some of the previous score, making the high score larger. Also, if the score I get is a negative number larger than the high score, it becomes the new high score only positive. Here is my high score view code:
import UIKit
class HighScore: ViewController {
#IBOutlet weak var HighscoreLabel: UILabel!
#IBOutlet weak var Scorelabel: UILabel!
#IBOutlet weak var NewHighscoreLabel: UILabel!
override func viewDidLoad() {
let defaults: NSUserDefaults = NSUserDefaults.standardUserDefaults()
var score = defaults.valueForKey("Score") as? String
Score = score?.stringByTrimmingCharactersInSet(NSCharacterSet.decimalDigitCharacterSet().invertedSet).toInt() ?? 0
Scorelabel.text = score
let SecondDefaults: NSUserDefaults = NSUserDefaults.standardUserDefaults()
var highscore = SecondDefaults.valueForKey("Highscore") as? String
Highscore = highscore?.stringByTrimmingCharactersInSet(NSCharacterSet.decimalDigitCharacterSet().invertedSet).toInt() ?? 0
HighscoreLabel.text = highscore
if Score < 0 {
NewHighscoreLabel.text = ""
}
else if Score > Highscore {
Highscore = 0
Highscore += Score
var HighscoreString:String = String(format: "Highscore:%i", Highscore)
let SecondDefaults: NSUserDefaults = NSUserDefaults.standardUserDefaults()
SecondDefaults.setObject(HighscoreString, forKey: "Highscore")
SecondDefaults.synchronize()
HighscoreLabel.text = highscore
NewHighscoreLabel.text = "New Highscore!"
}
}
}
Here is my saving code for the score on the actual game page:
var ScoreString:String = String(format: "Score:%i", Score)
ScoreLabel.text = (string: ScoreString)
let defaults: NSUserDefaults = NSUserDefaults.standardUserDefaults()
defaults.setObject(ScoreString, forKey: "Score")
defaults.synchronize()

Answer 1

First, some problems in your code: there is no need to create a SecondDefaults variable. It is always the same singleton referring to the defaults data base, so you can continue using your first variable defaults.
Variables, by convention, start with lower case letters. The use of your uppercase letters ivars is very confusing because they look like class names.
The logic is not quite clear because you are retrieving values from user defaults in viewDidLoad and then comparing them and re-setting some values. That does not seem logical. The user defaults entries should be in order when you read them - you should only adjust them when you evaluate a new score.
There are various other illogical lines, e.g.
highscore = 0
highscore += score
is exactly equivalent to
highscore = score
Back to your problem: you should not save your high score as a string. Not surprisingly, you run into all sorts of problems doing that because you have to encode and decode these strings. Instead, store your scores as numbers - you can just use them without having to parse strings.
The error you get is presumably because you have no value in one of the defaults entries. You should initialize your variables upon app start to make sure they are there. The best way to do this is the registerDefaults API.
let seedData = ["Score" : 0, "Highscore" : 0]
defaults.registerDefaults(seedData)
This will initialize them to 0 only if these keys are not already there.
The rest is easy:
let score = defaults.integerForKey("Score")!
scoreLabel.text = "\(score)"
let highscore = defaults.integerForKey("Highscore")!
highscore.text = "\(highscore)"
newHighscoreLabel.text = ""
Note that you can force unwrap with ! because you know the variables are initialized. As pointed out above, reading the score from user defaults does not make any sense. More likely you are displaying a score screen and get a new score value. Thus
defaults.setInteger(score, forKey: "Score")
let highscore = defaults.integerForKey("Highscore")!
if score > highscore {
defaults.setInteger(score, forKey: "Highscore")
newHighscoreLabel.text = "New Highscore!"
}