DemoSwiftLeak

DemoWeakTests.swift

import XCTest
@testable import DemoWeak

class DemoWeakTests: XCTestCase {
    
    override func setUp() {
        super.setUp()
        // Put setup code here. This method is called before the invocation of each test method in the class.
    }
    
    override func tearDown() {
        // Put teardown code here. This method is called after the invocation of each test method in the class.
        super.tearDown()
    }
    
    func testDelegateMemoryLeak() {
        let controller = ViewController()
        
        var observer = ObserverMock()
        weak var weakObserver = observer
        controller.addObserver(weakObserver!)
        
        observer = UIPageViewControllerDelegateMock()
        XCTAssertNil(weakObserver)
    }
    
    func ObserverMock() -> ManagerObserver {
        return ManagerObserver()
    }
}

UserManager.swift

class UserManager {
    private var observers = [ObserverWrapper]()
    
    public func addObserver(_ observer: ManagerObserver) {
        let wrapper = ObserverWrapper(observer: observer)
        observers.append(wrapper)
    }
}

private extension UserManager {
    struct ObserverWrapper {
        weak var observer: ManagerObserver?
    }
}

// define ManagerObserver
class ManagerObserver: NSObject, UIPageViewControllerDelegate {

}

ViewController.swift

protocol UIPageViewControllerDelegate {
    
}

class ViewController: UIViewController {
    private var observers = UserManager()
    
    func addObserver(_ observer: ManagerObserver) {
        observers.addObserver(observer)
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}