Method instances for defining singletons in Swift

This time I will show you how to define a singleton in Swift and what are the precautions for defining a singleton in Swift. The following is a practical case, let's take a look.

What is a singleton

Single case pattern is the simplest one among design patterns. Even some pattern masters do not call it a pattern, but call it an implementation technique, because the design pattern pays attention to the object. The abstraction of the relationship between objects, while the singleton mode has only one object of its own.

Singleton Pattern, also called monad pattern, is a commonly used software design pattern. When applying this pattern, the class of a singleton object must ensure that only one instance exists.

The Singleton design pattern may be the most widely discussed and used design pattern, and it may also be the most frequently asked design pattern in interviews. The main purpose of this design pattern is to ensure that only one instance of a class can appear in the entire system. Of course, this is necessary, such as the global configuration information of your software, or a Factory, or a main control class, etc.

How to create a singleton in swift

There are the following two ways to create a singleton in swift

The way of global variables

let sharedNetworkManager = NetworkManager(baseURL: API.baseURL)
class NetworkManager {
 // MARK: - Properties
 let baseURL: URL
 // Initialization
 init(baseURL: URL) {
 self.baseURL = baseURL
 }
}

Use this global variable for

reference

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
 print(sharedNetworkManager)
 return true
}

StaticAttributes and privatizationConstruction method

class NetworkManager {
 // MARK: - Properties
 private static var sharedNetworkManager: NetworkManager = {
 let networkManager = NetworkManager(baseURL: API.baseURL)
 // Configuration
 // ...
 return networkManager
 }()
 // MARK: -
 let baseURL: URL
 // Initialization
 private init(baseURL: URL) {
 self.baseURL = baseURL
 }
 // MARK: - Accessors
 class func shared() -> NetworkManager {
 return sharedNetworkManager
 }
}

Directly call the class method for reference

NetworkManager.shared()

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the PHP Chinese website!

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