Get image from URL thread safe

UIImageView+Nuke.swift

//
//  UIImageView+Nuke.swift
//  
//
//  Created by Aline e Tulio on 29/04/19.
//  Copyright © 2019 . All rights reserved.
//

import UIKit
import Nuke

public extension UIImageView {
    
    private static var kAssociationKeyImageTask = [String: ImageTask?]()
    
    var task: ImageTask? {
        get {
            let tmpAddress = String(format: "%p", unsafeBitCast(self, to: Int.self))
            return UIImageView.kAssociationKeyImageTask[tmpAddress] ?? nil
        }
        set(newValue) {
            let tmpAddress = String(format: "%p", unsafeBitCast(self, to: Int.self))
            UIImageView.kAssociationKeyImageTask[tmpAddress] = newValue
        }
    }
    
    public func setImage(with url: URL, placeholder: UIImage? = nil, callback: ((Error?) -> Void)? = nil) {
        task?.cancel()
        task = ImagePipeline.shared.loadImage(with: url, progress: nil) { (imageResponse, responseError) in
            if let error = responseError {
                self.image = placeholder
                guard let safeCallback = callback else { return }
                safeCallback(error)
                print("Job failed: \(error.localizedDescription)")
            } else {
                DispatchQueue.main.async {
                    UIView.animate(withDuration: 1.0, animations: {
                        self.image = imageResponse?.image
                        guard let safeCallback = callback else { return }
                        safeCallback(nil)
                    })
                }
               
            }
        }
    }
}