iOS mobile application first ever app launch detect

Question

I was trying to initiate an integer value in UserDefaults. But I want to do this operation once. At the first launch.

func application(_: UIApplication, didFinishLaunchingWithOptions _: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        UserDefaults.standard.set(-1, forKey: Constant.shared.empId)
       return true
    }

I tried this the above way. But didFinishLaunchingWithOptions is calling every time I launch the app. is there any function that is called once during the app's whole life cycle?

You can check whether the value exists (means launched before), before you assign the value for the first time. — Raptor, Mar 24 '23 at 09:20
Does this answer your question? [Swift - How to set initial value for NSUserDefaults](https://stackoverflow.com/questions/37830558/swift-how-to-set-initial-value-for-nsuserdefaults) — HangarRash, Mar 27 '23 at 02:33

score 1 · Answer 1 · answered Mar 24 '23 at 11:56

1

You need call:

UserDefaults.standard.register(
  defaults: {
    Constant.shared.empId: -1
  }
)

It will be called every time on app launch, but will not override value set with set method.

answered Mar 24 '23 at 11:56

Cy-4AH

4,370
2
15
22

It should be mentioned that this code would replace the OP's existing `UserDefaults` code in `didFinishLaunchingWithOptions`. – HangarRash Mar 27 '23 at 02:28

score 1 · Accepted Answer · answered Mar 27 '23 at 02:21

1

First, you can check whether userDefault contains any value or not. If it doesn't have any value, then you can set it. Following code may help you.

if UserDefaults.standard.object(forKey: Constant.shared.empId) != nil {
            
    print("UserDefaults has a value")
}
else {
    print("UserDefaults doesn't have a value")
    UserDefaults.standard.set(-1, forKey: Constant.shared.empId)
}

answered Mar 27 '23 at 02:21

Md. Ashikur Rahman

95
7

While this may work, it is far from the best solution. The other answer about registering a default is a much cleaner approach. – HangarRash Mar 27 '23 at 02:27

score -1 · Answer 3 · answered Mar 27 '23 at 03:24

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // Check if this is the first launch
    if UserDefaults.standard.bool(forKey: "isFirstLaunch") {
        // Perform any necessary setup tasks or show a welcome screen
        // ...
        
        // Set isFirstLaunch to false
        UserDefaults.standard.set(false, forKey: "isFirstLaunch")
    }
    
    return true
}

iOS mobile application first ever app launch detect

3 Answers3