Modern interface to UserDefaults + Codable support
Default
is a library that extends what UserDefaults
can do by providing extensions for saving custom objects that conform to Codable
and also providing a new interface to UserDefaults described below, via the protocol DefaultStorable
.
You can use only the Codable
support extensions or the DefaultStorable
protocol extensions or both. (or none, that's cool too)
- Read and write custom objects directly to
UserDefaults
that conform toCodable
- Provides an alternative API to
UserDefaults
withDefaultStorable
Feel free to open an Issue requesting the feature you want or send over a pull request!
This library has
Storing keys and values in defaults the normal way is error prone because typing out the string value for a key
every time leaves the possibility of mistyped keys and keeping track of which keys are used and what is currently stored in
UserDefaults
is somewhat hard.
Defining objects specifically for storing in user defaults makes the job of keeping track of what is currently being stored in UserDefaults
as simple as searching the project's source code for instances that conform to DefaultStorable
.
Using objects specifically for storing a set of data in UserDefaults allows settings for a certain piece of data to be logically grouped together.
Instead of manually adding key values to the key store or having to implement NSCoding
manually and bloating up
object code, you can simply and clearly define defaults objects with a clear intent of being used as a means of storing
defaults.
Much like how conforming to Codable
gets you a lot for free, so does conforming to DefaultStorable
.
**The object conforming to DefaultStorable
must also conform to Codable
:
Say we want to store theme settings in UserDefaults
(fair enough right?) we first define our object conforming to Codable
and DefaultStorable
.
struct VisualSettings: Codable, DefaultStorable {
let themeName: String
let backgroundImageURL: URL?
}
let settings = VisualSettings(themeName: "bright", backgroundImageURL: URL(string: "https://..."))
settings.write()
If you need to save the data under a different key other than the default key (the type name, in this case "VisualSettings"
) then this can be achieved by providing the optional argument to write(withKey:)
:
let settings = VisualSettings(themeName: "bright", backgroundImageURL: URL(string: "https://..."))
settings.write(withKey: "someUniqueKey")
if let settings = VisualSettings.read() {
// Do something
}
If you saved the default under a unque key then it can be read back by providing the optional argument to read(forKey:)
:
if let settings = VisualSettings.read(forKey: "someUniqueKey") {
// Do something
}
This library offers support for directly storing custom objects within UserDefaults
that conform to Codable
.
With the release of Swift 4 comes the Codable
protocol, which provides support for serializing objects.
UserDefaults
has not been updated to work with Swift 4's Codable
protocol so if saving custom objects directly to
UserDefaults
is necessary then that object must support NSCoding
and inherit from NSObject
.
// 1: Declare object (just conform to Codable, getting default encoder / decoder implementation for free)
struct VolumeSetting: Codable {
let sourceName: String
let value: Double
}
let setting = VolumeSetting(sourceName: "Super Expensive Headphone Amp", value: 0.4)
let key: String = String(describing: VolumeSetting.self)
// 2: Write
UserDefaults.standard.df.store(setting, forKey: key)
// 3: Read
UserDefaults.standard.df.fetch(forKey: key, type: VolumeSetting.self)
If the default behaviour of Default
does not quite fit your needs, then any of the default implementation details
can be overridden.
The most commonly overridden properties are defaultIdentifier
and defaults
.
defaultIdentifier
is the key by which your object will be stored.
This defaults to the type name of the object being stored.
public static var defaultIdentifier: String {
return String(describing: type(of: self))
}
defaults
will return the UserDefaults
database that your application will store defaults objects in.
The default implementation returns UserDefaults.standard
public static var defaults: UserDefaults {
return UserDefaults.standard
}
UserDefaults
requires custom types to confrom to NSCoding and be a subclass of NSObject
.
Doing that is a little time consuming, and conforming to NSCoding
requires implementing Decoding / Encoding methods
that take a bit of code to implement.
The good news is that Data
conforms to NSCoding
so if you can find a way to convert your object to Data
then you can store it in UserDefaults
, The Codable
protocol in Swift 4 does just that!
This library takes advantage of the Codable
protocol introduced in Swift 4.
The way it works is by taking an object that conforms to Codable
and encoding it into
a Data
object which can then be stored in UserDefaults
, then when you want to read it back out again just convert using Codable
again!
It's that Simple!
If you use Carthage to manage your dependencies, simply add
Default to your Cartfile
:
github "Nirma/Default"
If you use Carthage to build your dependencies, make sure you have added Default.framework
to the "Linked Frameworks and Libraries" section of your target, and have included Default.framework
in your Carthage framework copying build phase.
If you use CocoaPods to manage your dependencies, simply add
Default to your Podfile
:
pod 'Default'
- Xcode 9.0
- Swift 4.0+
Contributions are more than welcome!
Default is free software, and may be redistributed under the terms specified in the LICENSE file.