asynchronous - Swift async load image

Question

I am working on show image from url async. I have tried to create a new thread for download image and then refresh on main thread.

func asyncLoadImg(product:Product,imageView:UIImageView){
    let downloadQueue = dispatch_queue_create("com.myApp.processdownload", nil)
    dispatch_async(downloadQueue){
        let data = NSData(contentsOfURL: NSURL(string: product.productImage)!)
        var image:UIImage?
        if data != nil{
            image = UIImage(data: data!)
        }
        dispatch_async(dispatch_get_main_queue()){
            imageView.image = image
        }

    }
}

When I was trying to debug that, when it comes to dispatch_async(downloadQueue), it jumps out the func. Any suggestion? Thx

Answer 1

**Swift 5.0+ updated Code :

extension UIImageView {

    
        func imageFromServerURL(_ URLString: String, placeHolder: UIImage?) {

        self.image = nil
        //If imageurl's imagename has space then this line going to work for this
        let imageServerUrl = URLString.addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed) ?? ""
        

        if let url = URL(string: imageServerUrl) {
            URLSession.shared.dataTask(with: url, completionHandler: { (data, response, error) in

                //print("RESPONSE FROM API: (response)")
                if error != nil {
                    print("ERROR LOADING IMAGES FROM URL: (error)")
                    DispatchQueue.main.async {
                        self.image = placeHolder
                    }
                    return
                }
                DispatchQueue.main.async {
                    if let data = data {
                        if let downloadedImage = UIImage(data: data) {
                       
                            self.image = downloadedImage
                        }
                    }
                }
            }).resume()
        }
    }
}

Now wherever you required just do this to load image from server url :

1. Using swift 5.0 + updated code using placeholder image : UIImageView.imageFromServerURL(URLString:"here server url",placeHolder: placeholder image in uiimage format)

Simple !