我正在尝试实现一个代码，其中将在文件上传到 AWS 服务器后不久调用 API，但它必须处于后台模式。虽然 AWS sdk 在后台模式下管理将文件上传到他们的服务器，但以下代码不起作用。
ViewController.swift
func upload(_ mediaData:Data){
//AWS method to upload a file
AWSS3UploadImageData(mediaData!, strImageName: "person.jpg", strContentType: "img/*", { (isSuccess, result, strMessage) in
if isSuccess {
let arrPost = result as! [[String : String]]
//Call custom webservice
VaultUploadWebService.shared.callVaultUploadWebService(Params: arrPost)
}
else {
print("Unsuccess")
}
})
}
VaultWebService.swift
class VaultUploadWebService: NSObject {
static let shared = VaultUploadWebService()
var savedCompletionHandler: (() -> Void)?
func callVaultUploadWebService(Params: [[String : String]]) {
startRequest(for: "www.example.com", param: Params)
}
func startRequest (for urlString: String, param: [[String : String]]) {
let identifier = "com.com.background" + "\(NSDate().timeIntervalSince1970 * 1000)"
let configuration = URLSessionConfiguration.background(withIdentifier:identifier)
let session = URLSession(configuration: configuration, delegate: self, delegateQueue: nil)
let url = URL(string: urlString)!
var request = URLRequest(url: url, cachePolicy: .useProtocolCachePolicy, timeoutInterval: 180)
request.httpMethod = "post"
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
do {
let paramsData = try JSONSerialization.data(withJSONObject:param, options:[])
request.httpBody = paramsData
session.uploadTask(withStreamedRequest: request).resume()
}catch {
print("JSON serialization failed: ", error)
return
}
//Also tried using the following but no luck
/*guard let documentDirectoryUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else { return }
let fileUrl = documentDirectoryUrl.appendingPathComponent("Persons.json")
let jsonEncoder = JSONEncoder()
do {
let jsonData = try jsonEncoder.encode(param)
try jsonData.write(to: fileUrl, options: [])
}
catch let error {
print(error.localizedDescription)
}
session.uploadTask(with: request, fromFile: fileUrl).resume()*/
}
}
extension VaultUploadWebService: URLSessionDelegate {
func urlSessionDidFinishEvents(forBackgroundURLSession session: URLSession) {
DispatchQueue.main.async {
self.savedCompletionHandler?()
self.savedCompletionHandler = nil
}
}
}
extension VaultUploadWebService: URLSessionTaskDelegate{
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
if (error != nil){
print(error?.localizedDescription ?? "error")
}
else{
print(task.response)
}
}
}
最后.. Appdelegate.swift
func application(_ application: UIApplication, handleEventsForBackgroundURLSession identifier: String, completionHandler: @escaping () -> Void) {
let id = identifier as NSString
if id.contains("com.amazonaws") {
AWSS3TransferUtility.interceptApplication(application, handleEventsForBackgroundURLSession: identifier, completionHandler: completionHandler)
}else{
VaultUploadWebService.shared.savedCompletionHandler = completionHandler
}
}
但是这个委托(delegate)方法永远不会被调用，而它被调用用于 AWS 上传。我认为这是后台 uploadTask 对我不起作用的主要原因。卡了2天。任何帮助将不胜感激。
最佳答案
如果您通过 uploadTask(withStreamedRequest:) 创建上传任务，
httpBody 将被忽略。它需要实现 urlSession(_:task:needNewBodyStream:) 委托(delegate)回调。对于背景模式，它不适合。尝试使用 uploadTask(with request: URLRequest, from bodyData: Data) 代替。此外，它看起来像 VaultUploadWebService 没有对 session 对象的任何引用。尝试将 session 存储为 VaultUploadWebService 的成员。
关于ios - 后台上传在 Swift 中不起作用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51709220/