我想从我的应用程序中的URL加载图像,所以我首先尝试了Objective-C和它的工作,但是,与Swift,我有一个编译错误:

'imageWithData'不可用:使用对象构造'UIImage(data:)'

我的函数:

@IBOutlet var imageView : UIImageView

override func viewDidLoad() {
    super.viewDidLoad()

    var url:NSURL = NSURL.URLWithString("http://myURL/ios8.png")
    var data:NSData = NSData.dataWithContentsOfURL(url, options: nil, error: nil)

    imageView.image = UIImage.imageWithData(data)// Error here
}

在objective - c中:

- (void)viewDidLoad {
    [super viewDidLoad];

    NSURL *url = [NSURL URLWithString:(@"http://myURL/ios8.png")];
    NSData *data = [NSData dataWithContentsOfURL:url];

    _imageView.image = [UIImage imageWithData: data];
    _labelURL.text = @"http://www.quentinroussat.fr/assets/img/iOS%20icon's%20Style/ios8.png";
 }

有人能解释一下为什么imageWithData:不能与Swift一起工作,我该如何解决这个问题。


当前回答

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)

其他回答

干净的方式:

extension URL {
    var favIcon16: UIImage? { getFav(ofSize: .s) }
    var favIcon32: UIImage? { getFav(ofSize: .m) }
    var favIcon64: UIImage? { getFav(ofSize: .l) }
    var favIcon128: UIImage? { getFav(ofSize: .xl) }
    var favIcon256: UIImage? { getFav(ofSize: .xxl) }
    var favIcon512: UIImage? { getFav(ofSize: .xxxl) }

    private func getFav(ofSize s: FavSize) -> UIImage? {
        guard UIApplication.shared.canOpenURL(self),
              let favUrl = URL(string: "https://www.google.com/s2/favicons?sz=\(s.rawValue)&domain=\(self.absoluteURL)"),
              let data = try? Data(contentsOf: favUrl)
        else { return nil }
        return UIImage(data: data)
 }
    private enum FavSize: Int, CaseIterable { case s = 16, m = 32, l = 64, xl = 128, xxl = 256, xxxl = 512 }
}

和用法:

let myUrl = URL(string: "http://facebook.com")
myImgView.image = myUrl.favIcon16

Xcode 12•Swift 5

Leo Dabus的答案非常棒!我只是想提供一个一体化的功能解决方案:

if let url = URL(string: "http://www.apple.com/euro/ios/ios8/a/generic/images/og.png") {
    let task = URLSession.shared.dataTask(with: url) { data, response, error in
        guard let data = data, error == nil else { return }
        
        DispatchQueue.main.async { /// execute on main thread
            self.imageView.image = UIImage(data: data)
        }
    }
    
    task.resume()
}

斯威夫特4

这个方法将从一个网站异步下载图像并缓存它:

    func getImageFromWeb(_ urlString: String, closure: @escaping (UIImage?) -> ()) {
        guard let url = URL(string: urlString) else {
return closure(nil)
        }
        let task = URLSession(configuration: .default).dataTask(with: url) { (data, response, error) in
            guard error == nil else {
                print("error: \(String(describing: error))")
                return closure(nil)
            }
            guard response != nil else {
                print("no response")
                return closure(nil)
            }
            guard data != nil else {
                print("no data")
                return closure(nil)
            }
            DispatchQueue.main.async {
                closure(UIImage(data: data!))
            }
        }; task.resume()
    }

在使用:

    getImageFromWeb("http://www.apple.com/euro/ios/ios8/a/generic/images/og.png") { (image) in
        if let image = image {
            let imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
            imageView.image = image
            self.view.addSubview(imageView)
        } // if you use an Else statement, it will be in background
    }

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

供你参考:对于swift-2.0 Xcode7.0 beta2

extension UIImageView {
    public func imageFromUrl(urlString: String) {
        if let url = NSURL(string: urlString) {
            let request = NSURLRequest(URL: url)
            NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue()) {
            (response: NSURLResponse?, data: NSData?, error: NSError?) -> Void in
                self.image = UIImage(data: data!)
            }
        }
    }
}