Proof of Concept app to test behavior of CoreBluetooth on iOS. App contains State restoration, so app will be relaunched by system if dealloced from memory.
Peripheral app from BLE_Prototype_iOS project can be used as bluetooth device, that this app would automatically scan and connect to.
- INACTIVE = Launched Application. Peripheral instance is not existing. App may start scanning for Peripherals or retreive Peripheral instance by UUID
- CONNECTING = Application can start connecting to Peripheral. In this state application can connect within few seconds (if peripheral is in range) or wait for connection infinitelly "waiting connection" *
- CONNECTED = Peripheral was succesfully connected, so next communication can be started (Service and Characteristic discovering and R/W commands)
- DISCONNECTING = Peripheral may change into this state if disconnect is inicialized from Application
- DISCONNECTED = Initial state for peripheral (except of one scenario with App Restoration based on Bluetooth Event)
* Waiting connection is request made by application to connect to specific Peripheral. iOS handles those request even if application is not running and restores application if neccessary.
On foreground application can communicate with Peripherals without limitations. On Background situation is Much more difficult. App is limited to maximum 10s of computation time since last Bluetooth event.
Following scenarion can occur on background:
- System suspends application after 10s of bluetooth inactivity, aplication can resume if bluetooth activity occuress
- System removes application from memory, but application is restored after Peripheral is connected by iOS (thanks to waiting connections)
- System removes application from memory, no waiting connection is created, so application will not work on background.
|
| Bluetooth powered On | Application state | |||
|---|---|---|---|---|
| FALSE | Works after bluetooth is Powered On | |||
| TRUE | Works |
| State | Application works | Notes |
|---|---|---|
| Application quit by system | TRUE | |
| Application quit by user | FALSE | |
| Application crashed | TRUE | |
| Bluetooth power toggled | FALSE | Toggle Bluetooth power either through Settings, or via Airplane mode |
| Airplane mode toogled | TRUE | Only if bluetooth power is not toggled |
| Device restarted | TRUE | If the device requires a passcode to unlock, apps will not be relaunched until the device is unlocked for the first time after a restart |
| State | Application state | Notes | Control Center | |
|---|---|---|---|---|
| Powered off | Works only if App remains in memory (suspended state) | Toggle Bluetooth power either through Settings, or via Airplane mode |  |
|
| Partially on | Works after bluetooth state is changed to Powered On | Toggled in Control Center |  |
|
| Powered on | Works |  |
| State | Application works | Notes |
|---|---|---|
| Application quit by system | TRUE | |
| Application quit by user | FALSE | |
| Application crashed | TRUE | |
| Bluetooth power toggled | FALSE | Toggle Bluetooth power either through Settings, or via Airplane mode |
| Airplane mode toogled | TRUE | Only if bluetooth power is not toggled |
| Device restarted | TRUE | If the device requires a passcode to unlock, apps will not be relaunched until the device is unlocked for the first time after a restart |
| Issue | State |
|---|---|
| App bluetooth state might be incorrectly set to Powered Off after toggling Airplane mode | Reported to Apple |
| Link | |
|---|---|
| Use Airplane Mode on your iPhone, iPad, iPod touch, and Apple Watch | https://support.apple.com/en-us/HT204234 |
| iOS 11 Beta bluetooth state issue | https://forums.developer.apple.com/thread/83852 |
| Conditions Under Which Bluetooth State Restoration Will Relaunch An App | https://developer.apple.com/library/content/qa/qa1962/_index.html |
| Core Bluetooth Programming Guide | https://developer.apple.com/library/content/documentation/NetworkingInternetWeb/Conceptual/CoreBluetooth_concepts/AboutCoreBluetooth/Introduction.html |