I want to create an application similar to WhatsApp and Viber (maybe Skype), for iPhone starting from iOS 8.4, using swift 2.2. So I need to send https requests to my server every 30 seconds (I am using `NSURLSession), to show that my application is online and other contacts can see it. There is no problem with it if application is in active state, timer works perfectly and every 30 seconds. But I need application to work also in Inactive, Background, Suspended and Not running (if that even possible) modes, even if iPhone is sleeping. I just need to send little signal, thats all.
I already have this code:
func registerBackgroundTask() {
backgroundTask = UIApplication.sharedApplication().beginBackgroundTaskWithExpirationHandler {
[unowned self] in self.endBackgroundTask()
}
assert(backgroundTask != UIBackgroundTaskInvalid)
}
func endBackgroundTask() {
UIApplication.sharedApplication().endBackgroundTask(backgroundTask)
backgroundTask = UIBackgroundTaskInvalid
}
func reinstateBackgroundTask() {
if backgroundTask == UIBackgroundTaskInvalid {
registerBackgroundTask()
}
}
func functionToPerformOnBackground() {
requestToServer()
}
This functions are called by timer in AppDelegate.swift like this:
func applicationDidEnterBackground(application: UIApplication) {
//START BACKGROUND TIMER!!!
if !timerForBackgroundRunning {
timerForBackground = NSTimer.scheduledTimerWithTimeInterval(20, target: self, selector: "functionToPerformOnBackground", userInfo: nil, repeats: true)
registerBackgroundTask()
timerForBackgroundRunning = true
}
}
and
func applicationDidBecomeActive(application: UIApplication) {
if timerForBackgroundRunning {
timerForBackground.invalidate()
if backgroundTask != UIBackgroundTaskInvalid {
endBackgroundTask()
}
timerForBackgroundRunning = false
}
}
This code works perfectly, but when iPhone is going to sleep, it stops to send requests. To force code work again I have to go in application again and then press Home Button on iPhone. I have tested Viber and WhatsApp and I can say that Whatsapp is working similar, but Viber knows how to solve this problem.
Can somebody help me, please?
I will be thankful for any help, advice or anything.
P.S. I have already seen this tutorial: http://www.raywenderlich.com/92428/background-modes-ios-swift-tutorial
Is is great but not complete.
Related
The app is in the background and it receives a callback upon disconnection with the BLE device, after which the app has to wait for sometime(1minute) and then execute some piece of code. The app behaves as expected even when in the background if the screen is turned on. But if the screen is turned off then the timer is not working and the app is not executing as expected.
This is the code in AppDelegate to start a timer in background:
func startTimerWith(timeInterval: TimeInterval) {
registerBackgroundTask()
timer = Timer.scheduledTimer(withTimeInterval: timeInterval, repeats: false, block: { (timer) in
NotificationCenter.default.post(name: NSNotification.Name(rawValue: "Time"), object: nil)
self.endBackgroundTask()
})
}
func registerBackgroundTask() {
backgroundTask = UIApplication.shared.beginBackgroundTask(expirationHandler: {
self.endBackgroundTask()
})
}
func endBackgroundTask() {
print("Background task ended.")
UIApplication.shared.endBackgroundTask(backgroundTask)
backgroundTask = UIBackgroundTaskInvalid
timer?.invalidate()
timer = nil
}
When disconnected from the BLE device, I start the timer by registering to background task:
func disconnected(_ peripheral: CBPeripheral, with error: Error?) {
print("DISCONNECTED!!!")
AppDelegate.sharedApp().startTimerWith(timeInterval: TimeInterval(TIME))
BLEDeviceHandler.sharedInstance.handleBLEDevice(connectedPeripheral!)
}
Two points are vital here :
Timer doesn't work if the app is in background state for more than 10 minutes. I had an exact scenario where I had to perform some
action in background. I found out that after 10 minutes, timer didn't
work.
Timers do not work when the device is locked. App gets suspended immediately once the device is locked. This is for iOS >= 7.0
Bug is fixed its because app using location services but I forgot to given permission to update location when app is in background.
I have a timer app that I have made.
When I run it on the iPhone X on the simulator, the timer will run in the background just fine, but when I test it on my physical device (iPad Pro), it does not run in the background.
When I say in the background, I mean when you press the off button located on the top (iPad)/side (iPhone) of the device, so that the screen goes black.
Is this a glitch on the simulator's behalf, or something that I am not aware of, or is there something I need to change about my app to make it work in the background on PHYSICAL DEVICES as well?
Thanks
In DidBackground:
stop normalTimer.
start New backgroundTaskTimer
In WillForeground:
stop backgroundTaskTimer.
start normalTimer
Find below sample code:
In Appdelegate:
Declaration:
var backgroundUpdateTask: UIBackgroundTaskIdentifier!
var backgroundTaskTimer:Timer! = Timer()
Implementation:
func doBackgroundTask() {
DispatchQueue.global(qos: .default).async {
self.beginBackgroundTask()
if self.backgroundTaskTimer != nil {
self.backgroundTaskTimer.invalidate()
self.backgroundTaskTimer = nil
}
//Making the app to run in background forever by calling the API
self.backgroundTaskTimer = Timer.scheduledTimer(timeInterval: 10, target: self, selector: #selector(self.startTracking), userInfo: nil, repeats: true)
RunLoop.current.add(self.backgroundTaskTimer, forMode: RunLoopMode.defaultRunLoopMode)
RunLoop.current.run()
// End the background task.
self.endBackgroundTask()
}
}
func beginBackgroundTask() {
self.backgroundUpdateTask = UIApplication.shared.beginBackgroundTask(withName: "Track trip", expirationHandler: {
self.endBackgroundTask()
})
}
func endBackgroundTask() {
UIApplication.shared.endBackgroundTask(self.backgroundUpdateTask)
self.backgroundUpdateTask = UIBackgroundTaskInvalid
}
In ApplicationDidEnterBackground:
func applicationDidEnterBackground(_ application: UIApplication) {
//Start the background fetch
self.doBackgroundTask()
}
In ApplicationWillEnterForeground:
func applicationWillEnterForeground(_ application: UIApplication) {
if self.backgroundTaskTimer != nil {
self.backgroundTaskTimer.invalidate()
self.backgroundTaskTimer = nil
}
}
I am trying to perform the Finite-Length background task in my app. However, as of now my code is not executed before the app is suspended.
I've followed quite a few tutorials that claims the following to be the way, but obviously I'm getting something wrong. Relevant code should be posted below (please just ask for any clarification if I'm missing something):
class Manager {
private var backgroundTask: UIBackgroundTaskIdentifier = UIBackgroundTaskInvalid
init(){
// Add observer able of detecting when app will go to background
NotificationCenter.default.addObserver(self, selector: #selector(self.didEnterBackground(_:)), name: .UIApplicationDidEnterBackground, object: nil)
}
deinit {
// Observers removed when view controller is dismissed / deallocated
NotificationCenter.default.removeObserver(self)
}
// Routine performed when app will resign from active
#objc private func didEnterBackground(_ notification: Notification){
registerBackgroundTask()
// Code that needs to be executed before app is suspended ------
DispatchQueue.global().sync {
self.isBackgrounding = true
self.shutdownSession()
self.isConnected = false
self.isActivated = false
self.activate = false
self.connectionManager.closeConnectionToPeripherals()
}
// -----------------------------------------------------
self.endBackgroundTask()
}
func registerBackgroundTask() {
backgroundTask = UIApplication.shared.beginBackgroundTask { [weak self] in
self?.endBackgroundTask()
}
assert(backgroundTask != UIBackgroundTaskInvalid)
}
func endBackgroundTask() {
print("\n\n\nBackground task ended.\n\n\n")
UIApplication.shared.endBackgroundTask(backgroundTask)
backgroundTask = UIBackgroundTaskInvalid
}
}
I am facing a problem where the background task always seem to be ended before executing the code. How do I ensure that the code in my synchronous block gets executed before app is suspended?
I don't quite understand the "registerBackgroundTask()" either - even though the internet insists on implementing it this way - as it calls the endBackgroundTask().
You need to move your self.endBackgroundTask() call into your DispatchQueue block, right after self.connectionManager.closeConnectionToPeripherals().
The registerBackgroundTask method does not directly call self.endBackgroundTask(), instead it is only called if the background task expired. Usually, this happens if your app does not complete the task after ~30s in background.
I am developing an iOS app and I want to detect when the user connects/disconnects to Wifi even when the app is closed. I did a lot of research, but still didn't find any solutions to this problem.
Can someone point me in the general direction of how to do this?
It is not possible to detect network connection after the application is closed. The process is shut down and your code cannot be executed.
Check iOS application lifecycle for more details
Maybe you should considered option of application, that can run in background. This is of course possible in iOS, you need Capability type:Background Modes. Then you can check if wifi is availible.
For some unspecified time you can attain this by using Background Fetch.
override init() {
super.init()
initializeBackgroundTask()
NotificationCenter.default.addObserver(self, selector: #selector(networkHasChanged(notification:)), name: NSNotification.Name.reachabilityChanged, object: nil)
}
func networkHasChanged(notification : NSNotification) {
if let reachability = notification.object as? Reachability {
// Do whatever you want to do!!!
}
}
func initializeBackgroundTask() {
if bgTask == UIBackgroundTaskInvalid {
bgTask = UIApplication.shared.beginBackgroundTask(withName: "CheckNetworkStatus", expirationHandler: {
self.endBackgroundTask()
})
}
}
func endBackgroundTask() {
if deepLinkString == nil {
if (self.bgTask != UIBackgroundTaskInvalid) {
UIApplication.shared.endBackgroundTask(self.bgTask)
self.bgTask = UIBackgroundTaskInvalid
}
}
}
deinit {
NotificationCenter.default.removeObserver(self, name: NSNotification.Name.reachabilityChanged, object: nil)
}
Also try not to initialise background task if not in use.
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
var timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: Selector("update"), userInfo: nil, repeats: true)
}
func update() {
println("Something cool")
}
}
It's ok for the Simulator ，I will get continuous "Something cool" through I tapped the home button. But it worked out when I debug the app with my iPhone. I did't get anything when I tapped the home button and make my app run background.
Someone told me I can play a long blank music to make my App run in the background.But I don't know how to play music in the background with swift #matt
You can use beginBackgroundTaskWithExpirationHandler to get some background execution time.
class ViewController: UIViewController {
var backgroundTaskIdentifier: UIBackgroundTaskIdentifier?
override func viewDidLoad() {
super.viewDidLoad()
backgroundTaskIdentifier = UIApplication.sharedApplication().beginBackgroundTaskWithExpirationHandler({
UIApplication.sharedApplication().endBackgroundTask(self.backgroundTaskIdentifier!)
})
var timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: "update", userInfo: nil, repeats: true)
}
func update() {
println("Something cool")
}
}
Swift 3.0
backgroundTaskIdentifier = UIApplication.shared.beginBackgroundTask(expirationHandler: {
UIApplication.shared.endBackgroundTask(self.backgroundTaskIdentifier!)
})
This code was inspired by this answer, but I ported to swift.
This apparently only runs for 3 minutes on iOS 7+.
I'm willing to bet that you don't need to run a timer in the background, what you need is to know the time that has elapsed while you were suspended. That is a much better use of your resources than trying to play an empty sound file.
Use applicationWillResignActive and applicationDidBecomeActive to determine how much time has elapsed. First save the fireDate of your timer and invalidate it in applicationWillResignActive
func applicationWillResignActive(application: UIApplication) {
guard let t = self.timer else { return }
nextFireDate = t.fireDate
t.invalidate()
}
Next, determine how much time is left for the timer in applicationDidBecomeActive by comparing the time now to the fireDate you saved in the applicationWillResignActive call:
func applicationDidBecomeActive(application: UIApplication) {
guard let n = nextFireDate else { return }
let howMuchLonger = n.timeIntervalSinceDate(NSDate())
if howMuchLonger < 0 {
print("Should have already fired \(howMuchLonger) seconds ago")
target!.performSelector(selector!)
} else {
print("should fire in \(howMuchLonger) seconds")
NSTimer.scheduledTimerWithTimeInterval(howMuchLonger, target: target!, selector: selector!, userInfo: nil, repeats: false)
}
}
If you need a repeating one, just do math to figure out how many times the timer should have fired while in the background
let howManyTimes = abs(howMuchLonger) / repeatInterval
when I tapped the home button and make my app run background
No, that's a false assumption. When you tap the home button, you do not make your app run in the background. You make your app suspend in the background. Your code does not run when you are in the background.
Apps can get special permission to run in the background just in order to perform certain limited activities, like continuing to play music or continuing to use Core Location. But your app does none of those things, so it goes into the background and stops.
add this code in appdelegate for run a task in background , its working finely,
var backgroundUpdateTask: UIBackgroundTaskIdentifier = 0
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
return true
}
func applicationWillResignActive(application: UIApplication) {
self.backgroundUpdateTask = UIApplication.sharedApplication().beginBackgroundTaskWithExpirationHandler({
self.endBackgroundUpdateTask()
})
}
func endBackgroundUpdateTask() {
UIApplication.sharedApplication().endBackgroundTask(self.backgroundUpdateTask)
self.backgroundUpdateTask = UIBackgroundTaskInvalid
}
func applicationWillEnterForeground(application: UIApplication) {
self.endBackgroundUpdateTask()
}