对于Swift-3及以上版本:

extension UIImageView {
  public func imageFromUrl(urlString: String) {
    if let url = URL(string: urlString) {
        let request = URLRequest(url: url)
        NSURLConnection.sendAsynchronousRequest(request as URLRequest, queue: .main, completionHandler: { (response, data, error) in
            if let imageData = data as NSData? {
                self.image = UIImage(data: imageData as Data)
            }
        })
    }
  }
}

一个快速的黑客，如果你想快速检查图像从url

 let imageURL = NSURL(string: "https://farm2.staticflickr.com/1591/26078338233_d1466b7da2_m.jpg")
 let imagedData = NSData(contentsOfURL: imageURL!)!
 imageView?.image = UIImage(data: imagedData)

我在一个tableview中实现了一个只有图像的自定义单元格

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell{
        
        let cell = tableView.dequeueReusableCellWithIdentifier("theCell", forIndexPath: indexPath) as! customTableViewCell

        let imageURL = NSURL(string: "https://farm2.staticflickr.com/1591/26078338233_d1466b7da2_m.jpg")
        
        let imagedData = NSData(contentsOfURL: imageURL!)!
            
        cell.imageView?.image = UIImage(data: imagedData)
        
        return cell
        
    }

一种获取图像的方法是安全的，适用于Swift 2.0和X-Code 7.1:

static func imageForImageURLString(imageURLString: String, completion: (image: UIImage?, success: Bool) -> Void) {
    guard let url = NSURL(string: imageURLString),
        let data = NSData(contentsOfURL: url),
        let image = UIImage(data: data)
        else { 
            completion(image: nil, success: false); 
            return 
       }

    completion(image: image, success: true)
}

然后你可以像这样调用这个方法:

imageForImageURLString(imageString) { (image, success) -> Void in
        if success {
            guard let image = image 
                 else { return } // Error handling here 
            // You now have the image. 
         } else {
            // Error handling here.
        }
    }

如果你要用图像更新视图，你必须在" If success{"后面加上这个:

    dispatch_async(dispatch_get_main_queue()) { () -> Void in
         guard let image = image 
              else { return } // Error handling here 
         // You now have the image. Use the image to update the view or anything UI related here
         // Reload the view, so the image appears
    }

The reason this last part is needed if you are using the image in the UI is because network calls take time. If you try to update the UI using the image without calling dispatch_async like above, the computer will look for the image while the image is still being fetched, find that there is no image (yet), and move on as if there was no image found. Putting your code inside of a dispatch_async completion closure says to the computer, "Go, get this image and when you are done, then complete this code." That way, you will have the image when the code is called and things will work well.

斯威夫特 2.2 ||Xcode 7.3

我得到了惊人的成绩!!使用AlamofireImage swift库

它提供了多种功能，如:

异步下载 自动清除图像缓存，如果内存警告发生的应用程序 图像URL缓存 图像缓存 避免重复下载

在你的应用中很容易实现

步骤1安装吊舱

Alamofire 3 x 3。

宾夕法尼亚州’Alamofire’

AlamofireImage 2。4 . x

宾夕法尼亚州’AlamofireImage’

步骤2导入并使用

import Alamofire
import AlamofireImage

let downloadURL = NSURL(string: "http://cdn.sstatic.net/Sites/stackoverflow/company/Img/photos/big/6.jpg?v=f4b7c5fee820")!
imageView.af_setImageWithURL(downloadURL)

就是这样! !它会照顾好一切

非常感谢Alamofire的伙计们，让iDevelopers的生活变得简单了;)

您可以使用pod SDWebImage来实现相同的功能。它很容易使用。你可以在SDWebImage这里获得文档

下面是示例代码

self.yourImage.sd_setImage(with: NSURL(string: StrUrl as String ) as URL!, placeholderImage: placeholderImage, options: SDWebImageOptions(rawValue: 0), completed: { (image, error, cacheType, imageURL) in
                if( error != nil)
                {
                    print("Error while displaying image" , (error?.localizedDescription)! as String)
                }
            })

Xcode 8或更高版本•Swift 3或更高版本

同步:

if let filePath = Bundle.main.path(forResource: "imageName", ofType: "jpg"), let image = UIImage(contentsOfFile: filePath) {
    imageView.contentMode = .scaleAspectFit
    imageView.image = image
}

异步:

创建一个带有完成处理程序的方法，从您的url获取图像数据

func getData(from url: URL, completion: @escaping (Data?, URLResponse?, Error?) -> ()) {
    URLSession.shared.dataTask(with: url, completionHandler: completion).resume()
}

创建一个方法来下载映像(启动任务)

func downloadImage(from url: URL) {
    print("Download Started")
    getData(from: url) { data, response, error in
        guard let data = data, error == nil else { return }
        print(response?.suggestedFilename ?? url.lastPathComponent)
        print("Download Finished")
        // always update the UI from the main thread
        DispatchQueue.main.async() { [weak self] in
            self?.imageView.image = UIImage(data: data)
        }
    }
}

用法:

override func viewDidLoad() {
    super.viewDidLoad()
    print("Begin of code")
    let url = URL(string: "https://cdn.arstechnica.net/wp-content/uploads/2018/06/macOS-Mojave-Dynamic-Wallpaper-transition.jpg")! 
    downloadImage(from: url)
    print("End of code. The image will continue downloading in the background and it will be loaded when it ends.")
}

扩展:

extension UIImageView {
    func downloaded(from url: URL, contentMode mode: ContentMode = .scaleAspectFit) {
        contentMode = mode
        URLSession.shared.dataTask(with: url) { data, response, error in
            guard
                let httpURLResponse = response as? HTTPURLResponse, httpURLResponse.statusCode == 200,
                let mimeType = response?.mimeType, mimeType.hasPrefix("image"),
                let data = data, error == nil,
                let image = UIImage(data: data)
                else { return }
            DispatchQueue.main.async() { [weak self] in
                self?.image = image
            }
        }.resume()
    }
    func downloaded(from link: String, contentMode mode: ContentMode = .scaleAspectFit) { 
        guard let url = URL(string: link) else { return }
        downloaded(from: url, contentMode: mode)
    }
}

用法:

imageView.downloaded(from: "https://cdn.arstechnica.net/wp-content/uploads/2018/06/macOS-Mojave-Dynamic-Wallpaper-transition.jpg")