A package to specify a Key type for use with UserDefaults.
Generally you will want to extend the UserDefaultsKey to add a static property to allow easy access to the key.
extension UserDefaultsKey where Value == Bool {
static let somePreference = UserDefaultsKey("somePreference", default: false)
}Then you can access the value using the key with shorthand syntax. The value you get back will be the one specified at the declaration of the key.
let somePreference = UserDefaults.standard.value(for: .somePreference)
if somePreference {
} else {
}Because the key has the type of the value, you can only store a value of the correct type for that key.
UserDefaults.standard.set(true, for: .somePreference) // Works
UserDefaults.standard.set("true", for: .somePreference) // Fails to compileKeys can be defined with optional values, and can either then fall back to a default value or nil. The initialiser that only takes the key name will return a key that falls back to nil. When declaring optional keys, you will also need to supply the type for Value as a generic parameter.
extension UserDefaultsKey where Value == String? {
static let optionalPreference = UserDefaultsKey<String?>("optionalPreference")
}Once you have defined a key, you can pass it to the UserDefault property wrapper to allow succinct definitions of properties that are backed by user defaults.
struct Foo {
@UserDefault(.somePreference) var somePreference
}Because Swift infers the value type from the key, you don't need to specify it in the property definition. For clarity however, it may be desirable to do so.
struct Foo {
@UserDefault(.somePreference) var somePreference: Bool
func bar() {
if somePreference {
} else {
}
}
}