如何加快圖像下載速度

Question

我有一個循環，它獲取 imageUrls 數組並從中制作圖像，但速度很慢，有沒有辦法加快速度？

它看起來像這樣：

self.urlArray.forEach() { 
    let photoURL = URL(string: $0)
    guard let url = photoURL else {continue}
    let data = try? Data(contentsOf: url)
    guard let dataSafe = data else {continue}
    let finishedImage = UIImage(data: dataSafe)
    self.imagesArray.append(finishedImage)
}

Answer 1

您可以在后台線程中獲取數據，然后在主線程上更新 UIImageView。

let photoURL = URL(string: $0)
guard let url = photoURL else {continue}
DispatchQueue.global(qos: DispatchQoS.QoSClass.userInitiated).async{
    //fetch the image data in background
    let data = try? Data(contentsOf: url)
    guard let dataSafe = data else {continue}
    DispatchQueue.main.sync {
        //get back to main thread
        let finishedImage = UIImage(data: dataSafe)
        self.imagesArray.append(finishedImage)
    }
}