Singleton - Swift

The Singleton pattern ensures a class has only one instance and provides a global point of access to it. This is useful for managing shared resources or configurations. In Swift, we achieve this using a static instance property and a private initializer to prevent external instantiation. The example demonstrates a Logger class that manages logging functionality throughout the application. The shared property provides access to the unique instance. This approach is idiomatic Swift, leveraging static properties for global access and controlling object creation through initializer access control.

// Logger.swift

import Foundation

class Logger {
    static let shared = Logger()

    private init() {
        // Private initializer to prevent direct instantiation
    }

    func log(message: String) {
        let timestamp = DateFormatter.localizedString(from: Date(), format: "yyyy-MM-dd HH:mm:ss")
        print("[\(timestamp)] - \(message)")
    }
}

// Usage:
// Logger.shared.log(message: "Application started")
// Logger.shared.log(message: "User logged in")