UIImageView+Extension

import UIKit

let imageCache = NSCache<AnyObject, AnyObject>()

extension UIImageView {
    
    func loadImage(urlString: String) -> Void {
        
        if urlString.isEmpty { return }
        
        self.image = nil
        if let cachedImage = imageCache.object(forKey: urlString as AnyObject) as? UIImage {
            self.image = cachedImage
            return
        }
        
        guard let url = URL(string: urlString) else { return }
        
        let request = URLRequest(url: url)
        let dataTask = URLSession.shared.dataTask(with: request) {data, response, error in
            if error != nil { return }
            DispatchQueue.main.async {
                let downloadedImage = UIImage(data: data!)
                if let image = downloadedImage {
                    imageCache.setObject(image, forKey: urlString as AnyObject)
                    self.image = UIImage(data: data!)
                }
            }
        }
        dataTask.resume()
    }
}