UserDefaultsKey

A package to create and use typed keys for UserDefaults and @AppStorage.

Why?

@AppStorage is a newer API and it works nicer than UserDefaults but it's still not perfect also the interop leaves room for desires.

Keys are strings, so there is no code completion
Keys could represent any Type this type has to be remembered when retrieving the value
There is no nice way to set default values*
Even if there is a default value an optional is returned
Storing RawRepresentable in UserDefaults is cumbersome (actually store rawValue)
Retrieving RawRepresentable from UserDefaults is even more cumbersome

* With UserDefaults register(defaults:) has to be called. Which accepts a String keyed Dictionary which is prone to errors. Also if there is a central place for all used keys, the default values are probably stored elsewhere. With @AppStorage the default values can directly be set in the View while this is nice you might end up with many places where the default value has to be set. This can easily lead to inconsistencies.

Solution

Declare all used keys in one place and provide a default value where needed. The library takes care of converting RawRepresentable as expected.

Declare a key

extension UserDefaults.Key where Value == Int {
  static let myIntValue = Self("myIntValue")
  static let myOtherIntValue: Self = "myOtherIntValue"
}

extension UserDefaults.DefaultValueKey where Value == Int {
  static let myIntValueWithDefault = Self("myIntValueWithDefault", default: 42)
}

Usage

// Get Value
let myIntValue = UserDefaults.standard.integer(for: .myIntValue)

// Set Value
UserDefaults.standard.set(1234, for: .myIntValue)

struct MyView: View {
  @AppStorage(.myIntValue) var myIntValue = 1
  @AppStorage(.myIntValueWithDefault) var myIntValueWithDefault

  var body: some View {
    // ...
  }
}

Warning

Make sure you don't create a static let with the same variable name on both UserDefaults.Key and UserDefaults.DefaultValueKey. This won't compile if you use this key with UserDefaults. If you only use it with @AppStorage the result may be surprising.

Notes

Please create an Issue in case a function is missing.

jandamm / UserDefaultsKey