UIKit (iOS/tvOS) 的 LeakedViewControllerDetector

import LeakedViewControllerDetector

LeakedViewControllerDetector.onDetect() { leakedViewController, leakedView, message in
    #if DEBUG
    return true //show warning alert dialog
    #else
    //here you can log warning message to a server, e.g. Crashlytics
    return false //don't show warning to user
    #endif
}

//once the view is removed it will warn you if it (or any of its subviews) haven't deinnited: 
someView.removeFromSuperviewDetectLeaks()

override func viewDidLoad() {
    super.viewDidLoad() //don't forget this!
    ...
}

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated) //don't forget this!
    ...
}

override func viewDidDisappear(_ animated: Bool) {
    super.viewDidDisappear(animated) //don't forget this!
    ...
}

//navigationController?.viewControllers.remove(at:3)
navigationController?.viewControllers[3].removeFromParent()

//tabBarController?.viewControllers?.remove(at:3)
tabBarController?.viewControllers?[3].removeFromParent()

LeakedViewControllerDetector.onDetect(detectionDelay: 1.0) { leakedViewController, leakedView, message in
    return true
}

LeakedViewControllerDetector.onDetect() { leakedViewController, leakedView, message in
    //return nil to ignore:
    if let leakedViewController {
        if leakedViewController is IgnoreThisViewController {return nil}
        if type(of: leakedViewController).description() == "_IgnoreThisPrivateViewController" {return nil}
        if leakedViewController.view.tag == -1 {return nil}
    }
    if let leakedView {
        if leakedView is IgnoreThisView {return nil}
        if type(of: leakedView).description() == "_IgnoreThisPrivateView" {return nil}
        if leakedView.tag == -1 {return nil}
    }
    return true
}

import FirebaseCrashlytics

let error = NSError(domain: Bundle.main.bundleIdentifier!,
                      code: 8, //whatever number you fancy
                  userInfo: [NSLocalizedDescriptionKey: message])
Crashlytics.crashlytics().record(error: error)

#if DEBUG
let delay = 0.2
#else
let delay = 1.0
#endif
               
LeakedViewControllerDetector.onDetect(detectionDelay: delay) { leakedViewController, leakedView, message in
    //return nil to ignore warnings of certain Viewscontrollers/Views
    if let leakedViewController {
        // UIImagePickerController tends to leak for ~5 second when you close it
        if leakedViewController is UIImagePickerController {return nil}
        if leakedViewController is IgnoreThisViewController {return nil}
        if type(of: leakedViewController).description() == "_IgnoreThisPrivateViewController" {return nil}
        if leakedViewController.view.tag == -1 {return nil}
    }
    if let leakedView {
        if leakedView is IgnoreThisView {return nil}
        if type(of: leakedView).description() == "_IgnoreThisPrivateView" {return nil}
        if leakedView.tag == -1 {return nil}
    }

    #if DEBUG
    print(message)
    return true //show alert
    #else
    //log leak message to server:
    let error = NSError(domain: Bundle.main.bundleIdentifier ?? "bundleIdentifier",
                        code: 8,
                        userInfo: [NSLocalizedDescriptionKey: message])
    Crashlytics.crashlytics().record(error: error)
    return false //don't show alert
    #endif
}

#if DEBUG
LeakedViewControllerDetector.onDetect() { leakedViewController, leakedView, message in
    //insert ignore code here
    print(message)
    return true //show alert
}
#endif

override func viewDidDisappear(_ animated: Bool) {
    super.viewDidDisappear(animated)
           
    DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) { [weak self] in
        
        //when self is nil the ViewController has deinnited, so no leak
        guard let self = self else { return }
        
        //if all these properties are nil the ViewController is considered to have leaked
        if self.view.window == nil && self.parent == nil && self.presentedViewController == nil && (view == nil || view.superview == nil) {
            print("Leaked ViewController detected: \(self)")
        }
    }
}

DispatchQueue.main.asyncAfter(deadline: .now() + 10) {
    print(self)
}

DispatchQueue.main.asyncAfter(deadline: .now() + 10) { [weak self] in
    guard let self = self else {return}
    print(self)
}

NotificationCenter.default.addObserver(forName: NSNotification.Name(rawValue: "SomeNotification"), object: nil, queue: nil) { [weak self] notification in
    print(self)
}

NotificationCenter.default.addObserver(self, selector: #selector(someMethod), name: Notification.Name("SomeNotification"), object: nil)

weak var delegate: MyViewControllerDelegate?

self.presentationController?.delegate = self

self.presentingViewController?.presentedViewController?.presentationController?.delegate = self

override func viewDidDisappear(_ animated: Bool) {
    super.viewDidDisappear(animated)
    //it's tempting to do this, but don't
    navigationController?.presentationController?.delegate = nil
}

//since we're referencing alert inside the callbacks use unowned or weak or it will never deinit
let alert = UIAlertController.init(title: "Retain test", message: nil, preferredStyle: .alert)
alert.addAction(UIAlertAction.init(title: "Unowned", style: .default) { [unowned alert] action in
    print(alert)
})
alert.addAction(UIAlertAction.init(title: "Weak", style: .default) { [weak alert] action in
    print(alert!) //explicitly unwrapping weak alert works basically the same as using unowned
})
self.present(alert, animated: true)

//in UITextView subclass
override func removeFromSuperview() {
    let wasSelectable = isSelectable
    isSelectable = false
    super.removeFromSuperview()
    isSelectable = wasSelectable
}