![]() In just four days, learn how to create your own Twitter using Stream Chat, Algolia, 100ms, Mux, and RevenueCat. The mutability of value types lets you specifically choose what variables can be modified or not. For example: let savedArray defaults.object(forKey: 'SavedArray') as String String() SPONSORED Build a functional Twitter clone using APIs and SwiftUI with Stream's 7-part tutorial series. UserDefaults are persisted for backups and restores. UserDefaults saves its data in a local plists file on disk. This tutorial will show you how to use UserDefaults in Swift. such as user settings or app configuration. UserDefaults lets you store key-value pairs, where a key is always a String and value can be one of the following data types: Data, String, Number, Date, Array or Dictionary. They’re also useful when you want to create a shared, mutable state.Īs a general rule, start by creating your instance as an enum, then move to a struct if you need more customization, and finally move to class when needed. Here’s an example of how to use UserDefaults in Swift: Set Values let defaults UserDefaults.standard t. After that, we tell it to set an object with a specific key. = checks if two objects share the same memory address. Below is sample code of how to do that: let defaults UserDefaults.standard t ('Coding Explorer', forKey: 'userNameKey') So, the first line is getting a reference to something that can access NSUserDefaults with the standard class property. Use a reference type when comparing instance identity with = makes sense. You can find more info about closures in Swift's docs. Let’s experiment with structs and prove that they’re value types:Īdd the following code to your playground: // 1 struct Car There are a few different value types: struct, enum, and tuple. Value Types vs Reference Types Value TypesĪ value type instance is an independent instance and holds its data in its own memory allocation. You'll use it to experiment with the code in this tutorial. This is done inside the Capabilities tab of your target's settings – find iCloud, then flick its switch to be On.First, create a new Playground in Xcode. There is one final, important thing to do: you need to enable iCloud for your app. import Foundation // Access Shared Defaults Object let userDefaults UserDefaults. We access the shared defaults object through the standard class property of the UserDefaults class. With that prefix, MKiCloudSync will copy to iCloud only UserDefaults keys that start with sync – you can now choose what you want to sync just by naming your keys appropriately. You can only store arrays of strings, numbers, Date objects, and Data objects in the user's defaults database. The "sync" part is important, because chances are you won't want to sync everything to iCloud. You can also create your own user defaults, called a persistent domain, which you can read more about in the documentation. Now open your AppDelegate.swift file, find the didFinishLaunchingWithOptions method, and add this line to it: MKiCloudSync.start(withPrefix: "sync") In the example above, you use the class variable standard, which is available anywhere in your code, to get hold of the standard user defaults. I am doing everything in the viewDidLoad for this step so that I. I am going to create two suites so that we can see later on how each suite has a different value for the same key. All we have to do is initialize UserDefaults with the suiteName that we want to use. ![]() ![]() To actually use the library, open your new bridging header (it'll be called something like YourProject-Bridging-Header.h) and add this: #import "MKiCloudSync.h" The synchronize method is automatically invoked at periodic intervals, use this method only if you cannot wait for the automatic synchronization (for example, if your application is about to exit) or if you want to update the user defaults to what is on disk even though you have not made any changes. Creating a new suite with UserDefaults is super simple. ![]() Xcode will ask you if you want to create an Objective-C bridging header, and you should click "Create Bridging Header" - this is required because MKiCloudSync is written in Objective-C rather than Swift. Inside the zip file you'll find MKiCloudSync.h and MKiCloudSync.m, and you should drag them both into your Xcode project. To use it, go here and click Download Zip. It's open source and so easy to use you literally don't notice that it's there once you've added it to your app – it just silently syncs your UserDefaults values to and from iCloud. ![]() One such example is called MKiCloudSync and it's available from here. Fortunately, other developers have written simple wrappers around it so that you can forget about iCloud and focus on the interesting things instead – i.e., the rest of your app. IOS has a built-in iCloud sync system called NSUbiquitousKeyValueStore, but to be honest it's pretty unpleasant to work with. How to store UserDefaults options in iCloud ![]()
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