Apple Watch Background Mode? - ios

Question

I am developing apple watch application. when i run the app it is working fine. Now my problem is when the app goes to background mode, the app on the apple watch app will closing automatically. I am writing small code in iPhone app:
func viewDidLoad() {
if (WCSession.isSupported()) {
let session = WCSession.defaultSession()
session.delegate = self
session.activateSession()
// In your WatchKit extension, the value of this property is true when the paired iPhone is reachable via Bluetooth.
// On iOS, the value is true when the paired Apple Watch is reachable via Bluetooth and the associated Watch app is running in the foreground.
// In all other cases, the value is false.
if session.reachable {
lblStatus.text = "Reachable"
}
else
{
lblStatus.text = "Not Reachable"
}
func sessionReachabilityDidChange(session: WCSession)
{
if session.reachable {
dispatch_async(dispatch_get_main_queue(), {
self.lblStatus.text = "Reachable"
})
}
else
{
dispatch_async(dispatch_get_main_queue(), {
self.lblStatus.text = "Not Reachable"
})
}
}
}
}
in WatchExtention Code is
func someFunc() {
if (WCSession.isSupported()) {
let session = WCSession.defaultSession()
session.delegate = self
session.activateSession()
if session.reachable {
ispatch_async(dispatch_get_main_queue(), {
self.lblStatus.setText("Reachable")
})
}
else
{
dispatch_async(dispatch_get_main_queue(), {
self.lblStatus.setText("Not Reachable")
})
}
func sessionReachabilityDidChange(session: WCSession)
{
if session.reachable {
dispatch_async(dispatch_get_main_queue(), {
self.lblStatus.setText("Reachable")
})
}
else
{
dispatch_async(dispatch_get_main_queue(), {
self.lblStatus.setText("Not Reachable")
})
}
}
}
}
Now when enter to background in apple Watch the iPhone app showing Not reachable why ?

Answer 1

It's the default behavior of the AppleWatch, mainly to spare with resources like battery.
session.reachable property is true only when Apple Watch is reachable via Bluetooth and the associated Watch app is running in the
foreground in all other cases, the value is false.
In your case the second option which caused the problem I suppose the bluetooth connection is working.
Anyway the question is what do you like to reach.
Actually the simple rule is that you couldn't wake up the Watch from the iPhone but you could wake up the iPhone app from the Watch.
Two ways with three options to reach the watch when it's counterpart is in the background: send a complication update or send a message (2 options) in the background which will be available for the Watch when it will awake again.
All of them are part of the WCSession Class.
The two options for sending messages are:
- updateApplicationContext:error:
You can use this method to transfer a dictionary of data to the counterpart Watch app.iPhone sends context data when the opportunity arises, means when the Watch app arises.The counterpart’s session on the Watch gets the data with the session:didReceiveUpdate: method or from the receivedApplicationContext property.
You may call this method when the watch is not currently reachable.
The other option is sending data in the background like
- transferUserInfo:
You can use this method when you want to send a dictionary of data to the Watch and ensure that it is delivered. Dictionaries sent using this method are queued on the other device and delivered in the order in which they were sent. After a transfer begins, the transfer operation continues even if the app is suspended.
BUT true for both methods that they can only be called while the session is active. Calling any of these methods for an inactive or deactivated session is a programmer error.
The complication solution is a little bit different but belongs to the same WCSession Class as the earliers.
-transferCurrentComplicationUserInfo:
This method is specifically designed for transferring complication user info to the watch with the aim to be shown on the watch face immediately.
Of course it's available only for iOS, and using of this method counts against your complication’s time budget, so it's availability is limited.
The complication user info is placed at the front of the queue, so the watch wakes up the extension in the background to receive the info, and then the transfer happens immediately.
All messages received by your watch app are delivered to the session delegate serially on a background thread, so you have to switch to the main queue in case you'd like to use or presenting them for UI.

Answer 2

The WWDC talk on WatchConnectivity discusses "reachability" and its nuances in quite a lot of detail, so you should definitely give it a watch.
TL;DR: reachable on the watch is for the most part only going to be true/YES when the watch app's UI is visible on the screen.