How to set CADisplayLink in Swift with weak reference between target and CADisplayLink instance

Question

In Objective-C, we can init CADisplayLink with Proxy Pattern to break strong reference:

WeakProxy *weakProxy = [WeakProxy weakProxyForObject:self];
self.displayL         


        

Answer 1

This proxy class should just work. Don't forget to invalidate before the dealloc.

import UIKit

class CADisplayLinkProxy {

    var displaylink: CADisplayLink?
    var handle: (() -> Void)?

    init(handle: (() -> Void)?) {
        self.handle = handle
        displaylink = CADisplayLink(target: self, selector: #selector(updateHandle))
        displaylink?.add(to: RunLoop.current, forMode: .common)
    }

    @objc func updateHandle() {
        handle?()
    }

    func invalidate() {
        displaylink?.remove(from: RunLoop.current, forMode: .common)
        displaylink?.invalidate()
        displaylink = nil
    }
}

Usage:

class ViewController: UIViewController {

    var displaylinkProxy: CADisplayLinkProxy?

    override func viewDidLoad() {
        super.viewDidLoad()
        displaylinkProxy = CADisplayLinkProxy(handle: { [weak self] in
            self?.updateAnything()
        })
    }

    @objc func updateAnything() {
        print(Date())
    }
}