Question

我对Alamofire Image lib有疑问。我尝试下载图像然后杀死应用程序并关闭wifi。因此，当我启动没有连接的应用程序但我的图像没有显示时，我希望能够看到图像（第一次在商店中缓存）。

这里我的代码位于一个简单的UIViewController中，其中包含一个UIImage和一个UIButton，它允许仅为某些测试刷新视图：

import UIKit
import AlamofireImage

class ViewController: UIViewController {

@IBOutlet weak var firstImage: UIImageView!
@IBOutlet weak var descriptionLabel: UILabel!

var imageCache: ImageRequestCache = AutoPurgingImageCache()
let urlRequest = URLRequest(url: URL(string: "https://httpbin.org/image/jpeg")!)

@IBAction func refreshView(_ sender: Any) {
    self.requestFirstImage()
}

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    self.requestFirstImage()
}

func requestFirstImage() {

    let downloader = self.diskImageDownloader()
    downloader.download(self.urlRequest) { response in
        if let image = response.result.value {
            self.firstImage.image = image
            // Add image to cache
            self.imageCache.add(image, for: self.urlRequest, withIdentifier: "wolf")
            self.descriptionLabel.text = "Image added to cache"
        }
    }

    // If image is stored in cache show it
    if let image = self.imageCache.image(for: self.urlRequest, withIdentifier: "wolf") {
        self.firstImage.image = image
        self.descriptionLabel.text = "Image showed from cache"
    } else {
        self.descriptionLabel.text = "Impossible to show image from cache"
        // call image from disk here
        ------> Here how read image which is located in alamofireimage_disk_cache subfolder of the app ?
    }

}

func diskImageDownloader(diskSpaceMB: Int = 300) -> ImageDownloader {

    let diskCapacity = diskSpaceMB * 1024 * 1024
    let diskCache = URLCache(memoryCapacity: diskCapacity, diskCapacity: diskCapacity, diskPath: "alamofireimage_disk_cache")
    let configuration = URLSessionConfiguration.default
    configuration.urlCache = diskCache
    let downloader = ImageDownloader(configuration: configuration)
    UIImageView.af_sharedImageDownloader = downloader

    return downloader
}   
}

提前感谢您的帮助。

亲切的问候，

Answer 1

SDWebImage就是这样做的。当我第一次下载我的图像然后杀死我的应用程序。如果之后我在没有互联网的情况下重新启动它，将显示图像。

这里有一个例子：

import SDWebImage

@IBOutlet weak var myImage: UIImageView!            
let imageURL = URL(string:"Replace by url of image")

self.myImage.sd_setImage(with: imageURL!, placeholderImage:UIImage(named: "PlaceHolderImage")!)

您的信息“PlaceHolderImage”是我的资产中占位符图片的名称。所以用你的替换。此图像将在下载图像之前/期间出现。

不要忘记安装SDWebImage lib。在项目中使用此lib的三种方法：

使用CocoaPods
使用Carthage
将项目克隆到您的存储库

谢谢，祝你好运。

使用AlamofireImage重新启动应用后显示缓存的图像

1 个答案: