UIImageView+Extensions.swift

import UIKit

extension UIImageView {
    func downloadImageAsync(urlString: String, defaultImage: UIImage, success: @escaping ()->(), failure: @escaping ()->()) {
        if let image = ImageCache.shared.get(key: urlString) {
            self.image = image
        } else {
            // We can set default image here
            self.image = defaultImage
            DispatchQueue.global().async (execute: {
                guard let url = URL(string: urlString) else {
                    DispatchQueue.main.sync(execute: {
                        failure()
                    })
                    return
                }
                guard let data = try? Data(contentsOf: url) else {
                    DispatchQueue.main.sync(execute: {
                        failure()
                    })
                    return
                }
                guard let image = UIImage(data: data) else {
                    return
                }
                ImageCache.shared.set(key: urlString, image: image)
                DispatchQueue.main.sync (execute: {
                    self.image = image
                    success()
                })
            })
        }
    }
    
    func downloadImageAsync(url: String) {
        self.downloadImageAsync(urlString: url, defaultImage: UIImage(), success: {
            
        }, failure: {
            
        })
    }
    
    func downloadImageAsync(url: String, defaultImage: UIImage) {
        self.downloadImageAsync(urlString: url, defaultImage: defaultImage, success: {
            
        }, failure: {
            
        })
    }
}