Store variables to APP local.

iOS

Use UserDefaults to load & save key-value pairs in APP local.

I prefer to create a singleton Settings class to store all the local variables and load the values of these variables when the singleton class is initialized. Typically, I initialize the Settings class when the app starts.

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class Settings {
    
    static let shared: Settings = {
        let shared = Settings()
        return shared
    }()
    
    var userID = ""
    var userPwd = ""
    var devID = 0
    var enableDev = false
    
    private init(){
        print("Setting init")
        self.load()
    }
    
    func load(){
        self.userID = UserDefaults.standard.value(forKey: "uid") as? String ?? ""
        self.userPwd = UserDefaults.standard.value(forKey: "pwd") as? String ?? ""
        self.devID = UserDefaults.standard.value(forKey: "did") as? Int ?? 0
        self.enableDev = UserDefaults.standard.value(forKey: "enableDev") as? Bool ?? false
        
        print("userID=\(self.userID) userPwd=\(self.userPwd) devID=\(self.devID), enableDev=\(self.enableDev)")
    }

    func save(){
        UserDefaults.standard.set(self.userID, forKey: "uid")
        UserDefaults.standard.set(self.userPwd, forKey: "pwd")
        UserDefaults.standard.set(self.devID, forKey: "did")
        UserDefaults.standard.set(self.enableDev, forKey: "enableDev")
    }
}
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//Setting & saving the variables
Setting.shared.userID = "test123"
Setting.shared.userPwd = "12345678"
Setting.shared.devID = 1980
Setting.shared.enableDev = true

Setting.shared.save()

Android

Use SharedPreferences to load & save key-value pairs in APP local.

I prefer to create an application class to store all the local variables and initialize the values of these variables when the app starts. 

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class MyApplication: Application() {

    companion object{
        var userID = ""
        var userPwd = ""
        var devID = 0
        var enableDev = false

        var preferences: SharedPreferences? = null
        fun save(){
            preferences?.let {
                it.edit()
                    .putString("uid", MyApplication.userID)
                    .putString("pwd", MyApplication.userPwd)
                    .putInt("did", MyApplication.devID)
                    .putBoolean("enableDev", MyApplication.enableDev)
                    .apply()
            }
        }
    }

    override fun onCreate(){
        super.onCreate()
        preferences = getSharedPreferences( packageName + "_preferences", MODE_PRIVATE);
        load()
    }

    private fun load(){
        preferences?.let {
            userID = it.getString("uid", "")?:""
            userPwd = it.getString("pwd", "")?:""
            devID = it.getInt("did", 0)
            enableDev = it.getBoolean("enableDev", false)
        }
        println("userID=$userID userPwd=$userPwd devID=$devID, enableDev=$enableDev")
    }
}
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//Do remember to add the new application class to the AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.xxx.xxx">

    <application
        android:name=".MyApplication"
        ...
    </application>

</manifest>
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//Setting & saving the variables
MyApplication.userID = "test123"
MyApplication.userPwd = "12345678"
MyApplication.devID = 1980
MyApplication.enableDev = true

MyApplication.save()