我正在尝试在URLSession恢复后完成一个动作。
所以我使用url从我的服务器下载了几张图片，这些都很好用。但是现在我尝试在下载完毕后将这些图像保存到磁盘上。
问题
现在我可以在下载时将它们保存在同一个查询中，但我不想这样做，因为它会使我的查询变慢。
所以我用查询为我的func添加了一个完成处理程序，但是当我将图像保存到该块中的磁盘时，它可以正常工作，但我无法对我的屏幕做任何事情，因为查询尚未恢复，但它已被阻止接触我猜...
现在我希望能够在恢复查询后立即调用我的func将图像保存到磁盘....任何人都有任何想法？
如果有人需要更多解释或看到代码，请在下方发表评论
非常感谢任何有帮助的人！
下载代码
func loadPosts(completionHandler: @escaping (Bool) -> ()) {
pageNumber = 1
appDelegate.setNetworkActivityIndicatorVisible(true)
let id = user!["id"] as! String
let url = URL(string: "http://************/Files/Posts.php")!
var request = URLRequest(url: url)
request.httpMethod = "POST"
let body = "id=\(id)&caption=&uuid=&page="
request.httpBody = body.data(using: String.Encoding.utf8)
let task = URLSession.shared.dataTask(with: request, completionHandler: { (data:Data?, response:URLResponse?, error:Error?) in
DispatchQueue.global(qos: .background).async {
if error == nil {
let oldImageArray = self.cellContentArray
self.cellContentArray.removeAll(keepingCapacity: false)
do {
let json = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as? NSDictionary
guard let parseJSON = json else {
print("Error while parsing")
return
}
guard let posts = parseJSON["Posts"] as? [AnyObject] else {
print("Error while parseJSONing")
return
}
for element in posts {
// here I download the stuff and it to my Array, too long and no point to show here
}
let oldImageSet = Set(oldImageArray.map({return $0.uuid}))
let newImageSet = Set(self.cellContentArray.map({return $0.uuid}))
let addedImages = newImageSet.subtracting(oldImageSet)
let addedImageSections = Array(addedImages).map{ self.cellContentArray.map({return $0.uuid}).index(of: $0)! }
let addedImageIndexSet = IndexSet(addedImageSections)
let removedImages = oldImageSet.subtracting(newImageSet)
let removedImageSections = Array(removedImages).map{ oldImageArray.map({return $0.uuid}).index(of: $0)! }
let removedImageIndexSet = IndexSet(removedImageSections)
if !addedImageIndexSet.isEmpty {
if oldImageArray.count >= 5 {
self.lastUUIDImage = oldImageArray[4].uuid
} else {
}
self.coreDataShit()
}
DispatchQueue.main.async{
print(placeholderImage.count)
if placeholderImage.count > 5 {
placeholderImage.removeFirst(placeholderImage.count - 5)
}
print("finished")
self.customView.isHidden = true
if posts.count >= 5 {
self.tableView.addInfiniteScroll { [weak self] (scrollView) -> Void in
self?.loadMore()
}}
self.activityView.stopAnimating()
self.internetView.removeFromSuperview()
self.tableView.beginUpdates()
if !addedImageIndexSet.isEmpty {
self.tableView.insertSections(addedImageIndexSet, with: .top)
}
if !removedImageIndexSet.isEmpty {
self.tableView.deleteSections(removedImageIndexSet, with: .bottom)
}
self.tableView.endUpdates()
self.tableView.finishInfiniteScroll()
self.refresher.endRefreshing()
appDelegate.setNetworkActivityIndicatorVisible(false)
completionHandler(true)
}
} catch {
DispatchQueue.main.async {
self.tableView.removeInfiniteScroll()
self.customView.isHidden = false
self.refresher.endRefreshing()
self.tableView.reloadData()
}
}
} else {
DispatchQueue.main.async(execute: {
let message = error!.localizedDescription
appDelegate.infoView(message: message, color: smoothRedColor)
})
}
}
})
task.resume()
}
保存图片
self.loadPosts(completionHandler: { (true) in
print("completion")
let sections = self.tableView.numberOfSections
for i in 0..<sections {
self.rows += self.tableView.numberOfRows(inSection: i)
}
print(self.rows)
if self.rows <= 5 {
print("less than 5")
print(self.rows)
var i = 0
for element in self.cellContentArray {
let path = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as String
let dirPath = "\(path)/images"
let url = NSURL(fileURLWithPath: dirPath)
let filePath = url.appendingPathComponent("\(element.uuid).jpg")?.path
let fileManager = FileManager.default
if fileManager.fileExists(atPath: filePath!) {
print("File exsists")
} else {
print("File doesn't exsist")
DispatchQueue.main.async {
let url = NSURL(string: element.fullImage!)! // convert path str to url
let imageData = NSData(contentsOf: url as URL) // get data via url and assigned imageData
let imageName = element.uuid
let saveImages = FileSaveHelper(fileName: imageName, fileExtension: .JPG, subDirectory: "images", directory: .documentDirectory)
do {
guard let image = UIImage.sd_image(with: imageData as Data!) else {
print("Error getting image")
return
}
try saveImages.saveFile(image: image)
self.saveNewImagePath(imageLink: imageName, uuid: imageName)
self.removeImage(itemName: "file\(i)", fileExtension: "jpg")
self.removeImage(itemName: self.lastUUIDImage, fileExtension: "jpg")
i += 1
} catch {
print(error)
}
}
}
}
}
})
tableView Cell中的图像
self.postImage.sd_setImage(with: URL(string: content.fullImage!), placeholderImage: placeHolder, options: .retryFailed) { (image:UIImage?, error:Error?, cached:SDImageCacheType, url:URL?) in
}
答案 0 :(得分：1)
在您保存图片的代码中，这行代码阻止了您的用户界面
let imageData = NSData(contentsOf: url as URL) // get data via url and assigned imageData
这不是从服务器下载图像的正确方法，您应该使用URLSession