saving Set to NSUserDefaults

Question

I am storing a Set into NSUserDefaults with the following code. When I close the app and launch it again it breaks. There is something screwy going on with NSUserDefaults statement, because it works fine if I omit this code. What could be the reason?

var setOfStrings: Set<String>?


 func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

        let onlyAtFirstLaunch = NSUserDefaults.standardUserDefaults().objectForKey("arrayFromSet") as? Array<String>
        if onlyAtFirstLaunch == nil{
            setOfStrings = Set<String>()

        }else{
            let arrayFromSet = NSUserDefaults.standardUserDefaults().objectForKey("arrayFromSet") as! Array<String>

            setOfStrings! = Set(arrayFromSet)
        }
}



func applicationDidEnterBackground(application: UIApplication) {

    let arrayFromSet = Array(setOfStrings!)


    NSUserDefaults.standardUserDefaults().setObject(NSArray(array: arrayFromSet), forKey: "arrayFromSet")

    NSUserDefaults.standardUserDefaults().synchronize()
}

"it breaks". Please avoid such vague statements. How exactly does your code not work as expected? — rmaddy, Sep 16 '15 at 16:31

score 2 · Accepted Answer · edited Feb 15 '22 at 12:45

2

This line of code is causing the crash:

setOfStrings! = Set(arrayFromSet)

You are force unwrapping an optional var which is still nil;

Delete the "!" and it will fix the problem.

setOfStrings = Set(arrayFromSet)

edited Feb 15 '22 at 12:45

Sayalee Pote

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answered Sep 16 '15 at 16:41

wj2061

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saving Set to NSUserDefaults

1 Answers1