0
ボタンをクリックして、ダウンロードしたファイルを順番にダウンロードしてからダウンロードした後、表示するWebviewを開きます。しかし、すでに開いているwebviewを完了していないファイルをダウンロードしてしまいます。私は数日でいくつかのアプローチを見て、問題を解決する方法を知らない。誰も助けることができますか？Swift 3：ファイルを順次ダウンロードしてViewControllerを開く方法
多くのありがとうございます。
DownloadManagerクラス
class DownloadManager: NSObject {
/// Dictionary of operations, keyed by the `taskIdentifier` of the `URLSessionTask`
fileprivate var operations = [Int: DownloadOperation]()
/// Serial NSOperationQueue for downloads
private let queue: OperationQueue = {
let _queue = OperationQueue()
_queue.name = "download"
_queue.maxConcurrentOperationCount = 1 // I'd usually use values like 3 or 4 for performance reasons, but OP asked about downloading one at a time
return _queue
}()
/// Delegate-based NSURLSession for DownloadManager
lazy var session: URLSession = {
let configuration = URLSessionConfiguration.default
return URLSession(configuration: configuration, delegate: self, delegateQueue: nil)
}()
/// Add download
///
/// - parameter URL: The URL of the file to be downloaded
///
/// - returns: The DownloadOperation of the operation that was queued
@discardableResult
func addDownload(_ url: URL) -> DownloadOperation {
let operation = DownloadOperation(session: session, url: url)
operations[operation.task.taskIdentifier] = operation
queue.addOperation(operation)
return operation
}
/// Cancel all queued operations
func cancelAll() {
queue.cancelAllOperations()
}
}
// MARK: URLSessionDownloadDelegate methods
extension DownloadManager: URLSessionDownloadDelegate {
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
operations[downloadTask.taskIdentifier]?.urlSession(session, downloadTask: downloadTask, didFinishDownloadingTo: location)
}
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
operations[downloadTask.taskIdentifier]?.urlSession(session, downloadTask: downloadTask, didWriteData: bytesWritten, totalBytesWritten: totalBytesWritten, totalBytesExpectedToWrite: totalBytesExpectedToWrite)
}
}
// MARK: URLSessionTaskDelegate methods
extension DownloadManager: URLSessionTaskDelegate {
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
let key = task.taskIdentifier
operations[key]?.urlSession(session, task: task, didCompleteWithError: error)
operations.removeValue(forKey: key)
}
}
/// Asynchronous Operation subclass for downloading
class DownloadOperation : AsynchronousOperation {
let task: URLSessionTask
init(session: URLSession, url: URL) {
task = session.downloadTask(with: url)
super.init()
}
override func cancel() {
task.cancel()
super.cancel()
}
override func main() {
task.resume()
}
}
// MARK: NSURLSessionDownloadDelegate methods
extension DownloadOperation: URLSessionDownloadDelegate {
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
do {
let manager = FileManager.default
let destinationURL = try manager.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false)
.appendingPathComponent(downloadTask.originalRequest!.url!.lastPathComponent)
if manager.fileExists(atPath: destinationURL.path) {
try manager.removeItem(at: destinationURL)
}
try manager.moveItem(at: location, to: destinationURL)
} catch {
print("\(error)")
}
}
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
let progress = Double(totalBytesWritten)/Double(totalBytesExpectedToWrite)
print("\(downloadTask.originalRequest!.url!.absoluteString) \(progress)")
}
}
// MARK: NSURLSessionTaskDelegate methods
extension DownloadOperation: URLSessionTaskDelegate {
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
completeOperation()
if error != nil {
print("\(error)")
}
}
}
/// Asynchronous operation base class
///
/// This is abstract to class performs all of the necessary KVN of `isFinished` and
/// `isExecuting` for a concurrent `Operation` subclass. You can subclass this and
/// implement asynchronous operations. All you must do is:
///
/// - override `main()` with the tasks that initiate the asynchronous task;
///
/// - call `completeOperation()` function when the asynchronous task is done;
///
/// - optionally, periodically check `self.cancelled` status, performing any clean-up
/// necessary and then ensuring that `completeOperation()` is called; or
/// override `cancel` method, calling `super.cancel()` and then cleaning-up
/// and ensuring `completeOperation()` is called.
public class AsynchronousOperation : Operation {
override public var isAsynchronous: Bool { return true }
private let stateLock = NSLock()
private var _executing: Bool = false
override private(set) public var isExecuting: Bool {
get {
return stateLock.withCriticalScope { _executing }
}
set {
willChangeValue(forKey: "isExecuting")
stateLock.withCriticalScope { _executing = newValue }
didChangeValue(forKey: "isExecuting")
}
}
private var _finished: Bool = false
override private(set) public var isFinished: Bool {
get {
return stateLock.withCriticalScope { _finished }
}
set {
willChangeValue(forKey: "isFinished")
stateLock.withCriticalScope { _finished = newValue }
didChangeValue(forKey: "isFinished")
}
}
/// Complete the operation
///
/// This will result in the appropriate KVN of isFinished and isExecuting
public func completeOperation() {
if isExecuting {
isExecuting = false
}
if !isFinished {
isFinished = true
}
}
override public func start() {
if isCancelled {
isFinished = true
return
}
isExecuting = true
main()
}
}
/*
Copyright (C) 2015 Apple Inc. All Rights Reserved.
See LICENSE.txt for this sample’s licensing information
Abstract:
An extension to `NSLock` to simplify executing critical code.
From Advanced NSOperations sample code in WWDC 2015 https://developer.apple.com/videos/play/wwdc2015/226/
From https://developer.apple.com/sample-code/wwdc/2015/downloads/Advanced-NSOperations.zip
*/
extension NSLock {
/// Perform closure within lock.
///
/// An extension to `NSLock` to simplify executing critical code.
///
/// - parameter block: The closure to be performed.
func withCriticalScope<T>(block:() -> T) -> T {
lock()
let value = block()
unlock()
return value
}
}
[ダウンロード]ボタンをクリックしたときに、私はコードの下に呼び出します。
func downloadFiles() {
do {
var localJson: JSON?
let serverJson = self.serverJson
let str = serverJson?.description
let data = str?.data(using: .utf8)
let fileManager = FileManager.default
let documentsUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first! as URL
let oldManifestUrl = documentsUrl.appendingPathComponent("manifest.json")
let oldManifestPath = oldManifestUrl.path
if fileManager.fileExists(atPath: oldManifestPath) {
let jsonData = NSData(contentsOfFile:oldManifestPath)
localJson = JSON(data: jsonData! as Data)
}
var totalCount = 0
let downloadManager = DownloadManager()
for (index, subJson): (String, JSON) in serverJson! {
for (_, subJson): (String, JSON) in subJson {
let filepath = subJson["path"].stringValue
let nUpdated = subJson["updated"].stringValue
if let oUpdated = localJson?[index].array?.filter({ $0["path"].string == filepath}).first?["updated"].stringValue {
if (oUpdated == nUpdated) { continue }
}
var absPath = filepath
let strIdx = absPath.index(absPath.startIndex, offsetBy: 2)
if (absPath.hasPrefix("./"))
{
absPath = absPath.substring(from: strIdx)
}
let sourceUrl = URL(string: self.sourceUrl.appending(absPath))
downloadManager.addDownload(sourceUrl!)
}
}
// Remove temp json file first if exists.
if fileManager.fileExists(atPath: oldManifestPath) {
try? fileManager.removeItem(atPath: oldManifestPath)
}
// Write temp json file to local.
try data?.write(to: oldManifestUrl)
self.defaults.set(hashes, forKey: "LastHash")
let alertController = UIAlertController(title: "Information", message: "Download completed", preferredStyle: UIAlertControllerStyle.alert)
alertController.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil))
self.present(alertController, animated: true, completion: {
self.openWebView()
})
} catch {
print("Write JSON data to file failed, \(error.localizedDescription)")
}
}