Connection management

Once you discover the devices, is time to establish a connection with one of them. To do this you need a WLXConnectionManager. The WLXConnectionManager is a protocol that exposes an API to manage the connection with a device. As with the WLXDiscoverer, you ask for an object that implements the WLXConnectionManager to the WLXBluetoothDeviceManager through the method connectionManagerForPeripheral:usingReconnectionStrategy:.

To obtain a WLXConnectionManager you need a CBPeripheral and WLXReconnectionStrategy. You can get the CBPeripheral from the WLXDiscoveryData. As for the reconnection strategy you can create an instance of one the classes provided by the library or implement your own.

Once you get a WLXConnectionManager you can start a connection using one of the following methods: connectWithTimeout: or connectWithTimeout:usingBlock:. Both of this methods require a timeout (in milliseconds). After the timeout expires, if the connection cannot be established, an error will be raised. If you use the method that requires a block, that block will get called with an error or nil if the connection was successfully established.

If you want to be notified about the connection status, you can implement the WLXConnectionManagerDelegate that provides methods for every possible scenario:

• Connection established
• Fail to connect
• Connection lost
• Connection terminated
• Did reconnect
• Will attempt to reconnect

Reconnection strategies

The library provides a protocol to encapsulate the reconnection logic, WLXReconnectionStrategy. It also provides two concrete implementations: WLXLinearReconnectionStrategy and WLXNullReconnectionStrategy.

The WLXNullReconnectionStrategy, as its name suggests, does nothing. If the connection is lost a connection lost error will immediately be raised.

The WLXLinearReconnectionStrategy performs a linear back-off between each reconnection attempt. Every time a connection is lost this strategy will check if there are any remaining connection attempts. In such case, after waiting for a certain amount of time, it will try to reconnect. If there are no remaining reconnection attempts a connection lost error will be raised. To create an instance of WLXLinearReconnectionStrategy you must provide the following parameters:

• a wait time, that is the amount of time (in milliseconds) to wait between each reconnection attempt.
• the maximum amount of reconnection attempts.
• a connection timeout, you can use the same one you use for the first connection
• a dispatch queue, we recommend to provide the same one the device manager is using. You can getting by doing deviceManager.queue

Here is an example of how to create a linear reconnection strategy:

WLXBluetoothDeviceManager * deviceManager = ...;
id<WLXReconnectionStrategy> reconnectionStrategy =
[[WLXLinearReconnectionStrategy alloc] initWithWaitTime:2000
maxReconnectionAttempts:3
connectionTimeout:3000
queue:deviceManager.queue];

Notifications

The WLXConnectionManager also publishes connection related notifications using NSNotificationCenter. The following is a list of the notifications:

• WLXBluetoothDeviceConnectionEstablished: Published every time a connection is established. You can get the peripheral from the user info using the key WLXBluetoothDevicePeripheral.
• WLXBluetoothDeviceReconnectionEstablished: Published every time a reconnection is established. You can get the peripheral from the user info using the key WLXBluetoothDevicePeripheral.
• WLXBluetoothDeviceFailToConnect: Published when a connection with a peripheral could not be established. You can get the error from the NSNotification user info using the key WLXBluetoothDeviceError.
• WLXBluetoothDeviceConnectionLost: Published when a established connection with a peripheral is lost. You can get the error and the peripheral from the user info dictionary using the keys WLXBluetoothDeviceError and WLXBluetoothDevicePeripheral.
• WLXBluetoothDeviceConnectionTerminated: Published every time a the WLXConnecitonManager disconnect method is called and the connection is successfully terminated.
• WLXBluetoothDeviceReconnecting: Published every time a reconnection attempt is about to be executed. You can get the remaining reconnection attempts from the user info dictionary using the key WLXBluetoothDeviceRemainingReconnectionAttemps.

Device registry

A device registry encapsulates the logic of maintaining a registry of the connected devices, so the next time you want to connect with a device you do not have to discover a device a again. To create a new WLXBluetoothDeviceRegistry you need an object that conforms to the WLXBluetoothDeviceRepository protocol. The repository is the one that actually stores the required information to later be able to retrieve a peripheral. This information is encapsulated in a WLXBluetoothDeviceConnectionRecord.

Once you get an instance of WLXBluetoothDeviceRegistry you have to enable it, then every time a new connection is established the registry will save the connection record using the provided repository. To enable the registry you should set the enabled property to YES.

You can have more than one device registry but you probably need one. Keep in mind that if you have more than one registry they should use different repositories.

The library provides an repository that stores the last connection record into the user defaults, WLXBluetoothDeviceUserDefaultsRepository but you can have your own repository, say core data, by implementing the protocol WLXBluetoothDeviceRepository.

Examples

The following is an example of how to create a device registry using the user defaults repository:

WLXBluetoothDeviceManager * deviceManager = [WLXBluetoothDeviceManager deviceManager];
id<WLXBluetoothDeviceRepository> repository = [[WLXBluetoothDeviceUserDefaultsRepository alloc] initWithUserDefaults:[NSUserDefaults standardUserDefaults]];
WLXBluetoothDeviceRegistry * registry = [deviceManager deviceRegistryWithRepository:repository];
registry.enabled = YES;

Here is an example of how to establish a connection with a previously stored device:

id<WLXReconnectionStrategy> strategy = ...;
CBPeripheral * peripheral = registry.lastConnectedPeripheral;
id<WLXConnectionManager> connectionManager = [deviceManager connectionManagerForPeripheral:peripheral usingReconnectionStrategy:strategy];
[connectionManager connectWithTimeout:3000];