iOS：从网址加载图片

I need to load an image from a url and set it inside an UIImageView; the problem is that I don't know the exact size of the image, then how can I show the image correctly?

我需要从URL加载图像并将其设置在UIImageView中;问题是我不知道图像的确切大小，那么如何才能正确显示图像？

5 个解决方案

#1

111

Just use the size property of UIImage, for example:

只需使用UIImage的size属性，例如：

NSURL *url = [NSURL URLWithString:path];
NSData *data = [NSData dataWithContentsOfURL:url];
UIImage *img = [[UIImage alloc] initWithData:data];
CGSize size = img.size;

#2

In swift:

在迅捷：

var url = NSURL.URLWithString("http://www.example.com/picture.png")
var data = NSData(contentsOfURL : url)
var image = UIImage(data : data)
image.size // if you need it

#3

In swift regarding using optionals:

在快速使用期权：

var url:NSURL? = NSURL(string: imageString)
var data:NSData? = NSData(contentsOfURL : url!)
var image = UIImage(data : data!)

#4

IN SWIFT 3.0

在SWIFT 3.0中

The main thread must be always remain free so it serves the user interface and user interactions.

主线程必须始终保持空闲状态，以便为用户界面和用户交互提供服务。

class ViewController: UIViewController {

@IBOutlet weak var imageView: UIImageView!

private func fetchImage() {
    let imageURL = URL(string: "https://i.stack.imgur.com/9z6nS.png")
    var image: UIImage?
    if let url = imageURL {
        //All network operations has to run on different thread(not on main thread).
        DispatchQueue.global(qos: .userInitiated).async {
            let imageData = NSData(contentsOf: url)
            //All UI operations has to run on main thread.
            DispatchQueue.main.async {
                if imageData != nil {
                    image = UIImage(data: imageData as! Data)
                    self.imageView.image = image
                    self.imageView.sizeToFit()
                } else {
                    image = nil
                }
            }
        }
    }
}

override func viewDidLoad() {
    super.viewDidLoad()
    fetchImage()
}

}

#5

To download Asynchronous image with Kingfisher library you can follow this step,url :https://github.com/onevcat/Kingfisher:

要使用Kingfisher库下载异步映像，您可以按照以下步骤操作：urps：https：//github.com/onevcat/Kingfisher：

 func imageFromUrl(_ urlString: String) {
        if let url = URL(string: urlString) {
            ImageDownloader.default.downloadImage(with: url, options: [], progressBlock: nil) {
                (image, error, url, data) in
                DispatchQueue.main.async {
                    self.imageView.image = image
                }
            }
        }
    }

You can also download image with default URLSession.shared.dataTask

您还可以使用默认URLSession.shared.dataTask下载图像

 func imageFromUrl(_ urlString: String) {
        if let url = URL(string: urlString) {
            let request = URLRequest(url: url)
            URLSession.shared.dataTask(with: request) {(data,response,error) in
                if let imageData = data as Data? {
                    if let img = UIImage(data: imageData){
                       DispatchQueue.main.async {
                       self.imageView.image = img
                       }
                    }
                }
            }
        }
    }

#1

111