斯威夫特4::

这将在加载图像时显示加载器。 你可以使用NSCache临时存储图像

let imageCache = NSCache<NSString, UIImage>()
extension UIImageView {
    func loadImageUsingCache(withUrl urlString : String) {
        let url = URL(string: urlString)
        if url == nil {return}
        self.image = nil

        // check cached image
        if let cachedImage = imageCache.object(forKey: urlString as NSString)  {
            self.image = cachedImage
            return
        }

        let activityIndicator: UIActivityIndicatorView = UIActivityIndicatorView.init(activityIndicatorStyle: .gray)
        addSubview(activityIndicator)
        activityIndicator.startAnimating()
        activityIndicator.center = self.center

        // if not, download image from url
        URLSession.shared.dataTask(with: url!, completionHandler: { (data, response, error) in
            if error != nil {
                print(error!)
                return
            }

            DispatchQueue.main.async {
                if let image = UIImage(data: data!) {
                    imageCache.setObject(image, forKey: urlString as NSString)
                    self.image = image
                    activityIndicator.removeFromSuperview()
                }
            }

        }).resume()
    }
}

用法:-

truckImageView.loadImageUsingCache(withUrl: currentTruck.logoString)

使用Ascyimageview，你可以很容易地加载imageurl在imageview。

let image1Url：URL = URL（string： “（imageurl）” as String）！ imageview.imageURL=image1Url

翠鸟是一个最好的库加载图像到URL。

Github URL - https://github.com/onevcat/Kingfisher

// If you want to use Activity Indicator.
imageview_pic.kf.indicatorType = .activity
imageview_pic.kf.setImage(with: URL(string: "Give your url string"))

// If you want to use custom placeholder image.
imageview_pic.kf.setImage(with: URL(string: "Give your url string"), placeholder: UIImage(named: "placeholder image name"), options: nil, progressBlock: nil, completionHandler: nil)

斯威夫特5

extension UIImageView {
    func load(url: URL) {
        DispatchQueue.global().async { [weak self] in
            if let data = try? Data(contentsOf: url) {
                if let image = UIImage(data: data) {
                    DispatchQueue.main.async {
                        self?.image = image
                    }
                }
            }
        }
    }
}

使用

override func awakeFromNib() {
    super.awakeFromNib()
   if let url = URL(string:"<imageURLHere>"){
     imgView.load(url: url)
   }
}

从服务器加载图像:-

func downloadImage(from url: URL , success:@escaping((_ image:UIImage)->()),failure:@escaping ((_ msg:String)->())){
    print("Download Started")
    getData(from: url) { data, response, error in
        guard let data = data, error == nil else {
            failure("Image cant download from G+ or fb server")
            return
        }

        print(response?.suggestedFilename ?? url.lastPathComponent)
        print("Download Finished")
        DispatchQueue.main.async() {
             if let _img = UIImage(data: data){
                  success(_img)
            }
        }
    }
}
func getData(from url: URL, completion: @escaping (Data?, URLResponse?, Error?) -> ()) {
    URLSession.shared.dataTask(with: url, completionHandler: completion).resume()
}

用法:-

  if let url = URL(string: "http://www.apple.com/euro/ios/ios8/a/generic/images/og.png") {
                        self.downloadImage(from:url , success: { (image) in
                            print(image)

                        }, failure: { (failureReason) in
                            print(failureReason)
                        })
                    }

let url = NSURL.URLWithString("http://live-wallpaper.net/iphone/img/app/i/p/iphone-4s-wallpapers-mobile-backgrounds-dark_2466f886de3472ef1fa968033f1da3e1_raw_1087fae1932cec8837695934b7eb1250_raw.jpg");
var err: NSError?
var imageData :NSData = NSData.dataWithContentsOfURL(url,options: NSDataReadingOptions.DataReadingMappedIfSafe, error: &err)
var bgImage = UIImage(data:imageData)