Core Bluetooth State Restoration

0
votes

I am working on an app that reacts on disconnects of peripherals and I am now trying to adopt the ne state preservation and restoration introduced in iOS 7.

I did everything like the documentation says, means:

  1. I added the background mode for centrals.

  2. I always instantiate my central manager with the same unique identifier.

  3. I implemented the centralManager:willRestoreState: method.

When my App moves to background I kill it in the AppDelegate callback with an kill(getpid(), SIGKILL);. (Core Bluetooth State Preservation and Restoration Not Working, Can't relaunch app into background)

When I now disconnect a peripheral by removing the battery my app is being waked up as expected and launchOptions[UIApplicationLaunchOptionsBluetoothCentralsKey] contains the correct identifier BUT the centralManager:willRestoreState: was not called. Only if I disconnect another peripheral this method gets called.

1
iosios7bluetoothcore-bluetoothcbcentralmanager
Bluetooth acts weird sometimes. This happened to me too, restarted device, suddenly it worked. Also, the last thing your app does before being killed may need to be either scanning or attempting to connect a peripheral. – Yazid
You do need to instantiate the central manager again though, or else willRestoreState: will not be called. – OutOnAWeekend

1 Answers

1
votes

This is how I have it:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{

    NSArray *peripheralManagerIdentifiers = launchOptions[UIApplicationLaunchOptionsBluetoothPeripheralsKey];

    if (peripheralManagerIdentifiers) {

        // We've restored, so create the _manager on the main queue
        _manager = [[CBPeripheralManager alloc] initWithDelegate:self
                                                          queue:dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)
                                                        options:@{CBPeripheralManagerOptionRestoreIdentifierKey:@"YourUniqueIdentifier"}];

    } else {

        // Not restored so just create as normal
        manager = [[CBPeripheralManager alloc] initWithDelegate:self
                                                          queue:nil
                                                        options:@{CBPeripheralManagerOptionRestoreIdentifierKey:@"YourUniqueIdentifier"}];

    }
return YES;
}

And then:

- (void)peripheralManager:(CBPeripheralManager *)peripheral
         willRestoreState:(NSDictionary *)dict
{


    // This is the advertisement data that was being advertised when the app was terminated by iOS
    _advertisementData = dict[CBPeripheralManagerRestoredStateAdvertisementDataKey];

    NSArray *services = dict[CBPeripheralManagerRestoredStateServicesKey];

    // Loop through the services, I only have one service but if you have more you'll need to check against the UUID strings of each
    for (CBMutableService *service in services) {

        _primaryService = service;

        // Loop through the characteristics
        for (CBMutableCharacteristic *characteristic in _primaryService.characteristics) {

            if ([characteristic.UUID.UUIDString isEqualToString:CHARACTERISTIC_UUID]) {

                _primaryCharacteristic = characteristic;

                NSArray *subscribedCentrals = characteristic.subscribedCentrals;

                // Loop through all centrals that were subscribed when the app was terminated by iOS
                for (CBCentral *central in subscribedCentrals) {

                    // Add them to an array
                    [_centrals addObject:central];

                }
            }
        }
    }
}