Kotlin Delegated (SharedPreferences)

BetterSharedPreferences.kt

fun SharedPreferences.string(
    defaultValue: String = "",
    key: (KProperty<*>) -> String = KProperty<*>::name
): ReadWriteProperty<Any, String> =
    object : ReadWriteProperty<Any, String> {
        override fun getValue(
            thisRef: Any,
            property: KProperty<*>
        ) = getString(key(property), defaultValue)
        override fun setValue(
            thisRef: Any,
            property: KProperty<*>,
            value: String
        ) = edit().putString(key(property), value).apply()
    }


fun SharedPreferences.stringNullable(
    defaultValue: String? = null,
    key: (KProperty<*>) -> String = KProperty<*>::name
): ReadWriteProperty<Any, String?> =
    object : ReadWriteProperty<Any, String?> {
        override fun getValue(
            thisRef: Any,
            property: KProperty<*>
        ) = getString(key(property), defaultValue)

        override fun setValue(
            thisRef: Any,
            property: KProperty<*>,
            value: String?
        ) = edit().putString(key(property), value).apply()
    }

fun SharedPreferences.int(
    defaultValue: Int = 0,
    key: (KProperty<*>) -> String = KProperty<*>::name
): ReadWriteProperty<Any, Int> =
    object : ReadWriteProperty<Any, Int> {
        override fun getValue(
            thisRef: Any,
            property: KProperty<*>
        ) = getInt(key(property), defaultValue)

        override fun setValue(
            thisRef: Any,
            property: KProperty<*>,
            value: Int
        ) = edit().putInt(key(property), value).apply()
    }