REST Call Doesn't Complete When Locking Screen

Question

I perform a REST call whenever the application the application becomes inactive. I make the call within the AppDelegate's applicationWillResignActive method. The call works perfectly if the user clicks the home button on the device, but if a user locks the screen while the application is still in the foreground, the call appears to send, but never completes and I don't receive the call on the server side.

I even attempted what was mentioned in the Creating a Manager with Background Configuration section, but the result has been the same. When using the background configuration, I do receive the error Error Domain=NSURLErrorDomain Code=-997 "Lost connection to background transfer service". This is the code I currently have:

    var deviceId:String
    // Check if deviceId has been stored
    if let device: String = NSUserDefaults.standardUserDefaults().stringForKey(Globals.KEY_DEVICE_ID) {
        // deviceId is stored, use it
        deviceId = device
    } else {
        // deviceId not stored, create a new one and store it
        deviceId = NSUUID().UUIDString
        NSUserDefaults.standardUserDefaults().setObject(deviceId, forKey: Globals.KEY_DEVICE_ID)
    }

    let params = ["statusId": "2"]
    let url = "client/device/" + deviceId

    // Create the URL Request
    let URLRequest = NSMutableURLRequest(URL: NSURL(string: Globals.BASE_URL + url)!)
    // set header fields
    if let key = NSUserDefaults.standardUserDefaults().stringForKey(Globals.NS_KEY_SESSION) {
        URLRequest.setValue(key, forHTTPHeaderField: "X-XX-API")
    }
    // Add user agent
    if let userAgent = NSUserDefaults.standardUserDefaults().stringForKey(Globals.NS_KEY_USER_AGENT) {
        URLRequest.setValue(userAgent, forHTTPHeaderField: "User-Agent")
    }

    // Set the HTTP method
    URLRequest.HTTPMethod = Alamofire.Method.PUT.rawValue

    let configuration = NSURLSessionConfiguration.backgroundSessionConfigurationWithIdentifier("com.myapp.background")
    manager = Alamofire.Manager(configuration: configuration)

    let encodeMethod: Alamofire.ParameterEncoding = Alamofire.ParameterEncoding.URL
    manager.startRequestsImmediately = true
    manager.request(encodeMethod.encode(URLRequest, parameters: params).0).validate().responseJSON() {
        (response) in

        print("response from call: \(response)")
        self.manager = nil
    }

I am using XCode 7.1 with deployment target 9.1 and Alamofire version 3.1.2.

score 1 · Answer 1 · edited May 23 '17 at 11:44

1

I found out I needed to use beginBackgroundTaskWithExpirationHandler. This post helped me out with the answer: objective c - Proper use of beginBackgroundTaskWithExpirationHandler.

edited May 23 '17 at 11:44

Community

1
1

answered Nov 24 '15 at 20:19

Mike Walker

2,944
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If you are targeting iOS 8.1 or later the newer `NSProcessInfo` APIs are preferred to `beginBackgroundTaskWithExpirationHandler`. This was covered extensively at WWDC in 2015. – quellish Nov 24 '15 at 20:30
Can you be more precise? 4 years after it's still an issue :p – Romain Sickenberg Oct 24 '19 at 14:56

REST Call Doesn't Complete When Locking Screen

1 Answers1