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singletonswift3

Singleton with properties in Swift 3

In Apple's Using Swift with Cocoa and Objective-C document (updated for Swift 3) they give the following example of the Singleton pattern:

class Singleton {
    static let sharedInstance: Singleton = {
        let instance = Singleton()

        // setup code

        return instance
    }()
}

Let's imagine that this singleton needs to manage a variable array of Strings. How/where would I declare that property and ensure it gets initialized properly to an empty [String] array?

Solution

  • For me this is the best way, make init private. Swift 3 \ 4 \ 5 syntax

    // MARK: - Singleton

final class Singleton {

    // Can't init is singleton
    private init() { }

    // MARK: Shared Instance

    static let shared = Singleton()

    // MARK: Local Variable

    var emptyStringArray = [String]()

}