SwiftyBluetooth

Fully featured closures based library for CoreBluetooth on iOS 9+ devices.

Background

CoreBluetooth and its delegate based API can be difficult to use at time. Often times you already know the specifications of the peripheral you're about to use and simply want to read or write to predetermined characteristics.

SwiftyBluetooth tries to address these concerns by providing a clear, closure based, API for every CBCentralManager and CBPeripheral calls. Furthermore, all your calls are guaranteed to timeout in case of untraceable errors. If required, SwiftyBluetooth will also take care of connecting to peripherals and discovering the required attributes when executing read or write operations lowering the amount of work you need to do.

Features

• Supports Swift 4 ~> v1.0.0, for Swift 3 use v0.3.4
• Synthaxic sugar and helper functions for common CoreBluetooth tasks
• Closure based CBCentralManager peripheral scanning with a timeout
• Notification based event for CBCentralManager state changes and state restoration
• Closure based calls for every CBPeripheral operations
• Notification based event for CBPeripheral name updates, characteristic value updates and services updates
• Precise errors and guaranteed timeout for every Bluetooth operation
• Full documentation for all public interfaces

Usage

The Library has 2 important class:

• The Central class, a Singleton wrapper around CBCentralManager used to scan for peripherals with a closure callback and restore previous sessions.
• The Peripheral class, a wrapper around CBPeripheral used to call CBPeripheral functions with closure callbacks.

Note: The library is currently not thread safe, make sure to run your Central and Peripheral operations on the main thread.

Below are a couple examples of operations that might be of interest to you.

Scanning for Peripherals

Scan for peripherals by calling scanWithTimeout(...) while passing a timeout in seconds and a callback closure to receive Peripheral result callbacks as well as update on the status of your scan:

// You can pass in nil if you want to discover all Peripherals
SwiftyBluetooth.scanForPeripherals(withServiceUUIDs: nil, timeoutAfter: 15) { scanResult in
    switch scanResult {
        case .scanStarted:
            // The scan started meaning CBCentralManager scanForPeripherals(...) was called 
        case .scanResult(let peripheral, let advertisementData, let RSSI):
            // A peripheral was found, your closure may be called multiple time with a .ScanResult enum case.
            // You can save that peripheral for future use, or call some of its functions directly in this closure.
        case .scanStopped(let error):
            // The scan stopped, an error is passed if the scan stopped unexpectedly
    }
}        

Note that the callback closure can be called multiple times, but always start and finish with a callback containing a .scanStarted and .scanStopped result respectively. Your callback will be called with a .scanResult for every unique peripheral found during the scan.

Connecting to a peripheral

peripheral.connect { result in 
    switch result {
    case .success:
        break // You are now connected to the peripheral
    case .failure(let error):
        break // An error happened while connecting
    }
}

Reading from a peripheral's service's characteristic

If you already know the characteristic and service UUIDs you want to read from, once a peripheral has been found you can read from it right away like this:

peripheral.readValue(ofCharacWithUUID: "2A29", fromServiceWithUUID: "180A") { result in
    switch result {
    case .success(let data):
        break // The data was read and is returned as an NSData instance
    case .failure(let error):
        break // An error happened while attempting to read the data
    }
}

This will connect to the peripheral if necessary and ensure that the characteristic and service needed are discovered before reading from the characteristic matching characteristicUUID. If the charac/service cannot be retrieved you will receive an error specifying which charac/service could not be found.

If you have a reference to a CBCharacteristic, you can read using the characteristic directly:

peripheral.readValue(ofCharac: charac) { result in
    switch result {
    case .success(let data):
        break // The data was read and is returned as a Data instance
    case .failure(let error):
        break // An error happened while attempting to read the data
    }
}

Writing to a Peripheral's service's characteristic

If you already know the characteristic and service UUID you want to write to, once a peripheral has been found, you can write to that characteristic right away like this:

let data = String(0b1010).dataUsingEncoding(NSUTF8StringEncoding)!
peripheral.writeValue(ofCharacWithUUID: "1d5bc11d-e28c-4157-a7be-d8b742a013d8", 
                      fromServiceWithUUID: "4011e369-5981-4dae-b686-619dc656c7ba", 
                      value: data) { result in
    switch result {
    case .success:
        break // The write was successful.
    case .failure(let error):
        break // An error happened while writting the data.
    }
}

Receiving Characteristic update notifications

Receiving characteristic value updates is done through notifications on the default NotificationCenter. All supported Peripheral notifications are part of the PeripheralEvent enum. Use this enum's raw values as the notification string when registering for notifications:

// First we prepare ourselves to receive update notifications 
let peripheral = somePeripheral

NotificationCenter.default.addObserver(forName: Peripheral.PeripheralCharacteristicValueUpdate,
                                        object: peripheral, 
                                        queue: nil) { (notification) in
    let charac = notification.userInfo!["characteristic"] as! CBCharacteristic
    if let error = notification.userInfo?["error"] as? SBError {
        // Deal with error
    }
}

// We can then set a characteristic's notification value to true and start receiving updates to that characteristic
peripheral.setNotifyValue(toEnabled: true, forCharacWithUUID: "2A29", ofServiceWithUUID: "180A") { (isNotifying, error) in
    // If there were no errors, you will now receive Notifications when that characteristic value gets updated.
}

Discovering services

Discover services using the discoverServices(...) function:

peripheral.discoverServices(withUUIDs: nil) { result in
    switch result {
    case .success(let services):
        break // An array containing all the services requested
    case .failure(let error):
        break // A connection error or an array containing the UUIDs of the services that we're not found
    }
}

Like the CBPeripheral discoverServices(...) function, passing nil instead of an array of service UUIDs will discover all of this Peripheral's services.

Discovering characteristics

Discover characteristics using the discoverCharacteristics(...) function. If the service on which you are attempting to discover characteristics from has not been discovered, an attempt will first be made to discover that service for you:

peripheral.discoverCharacteristics(withUUIDs: nil, ofServiceWithUUID: "180A") { result in
    // The characteristics discovered or an error if something went wrong.
    switch result {
    case .success(let services):
        break // An array containing all the characs requested.
    case .failure(let error):
        break // A connection error or an array containing the UUIDs of the charac/services that we're not found.
    }
}

Like the CBPeripheral discoverCharacteristics(...) function, passing nil instead of an array of service UUIDs will discover all of this service's characteristics.

State preservation

SwiftyBluetooth is backed by a CBCentralManager singleton wrapper and does not give you direct access to the underlying CBCentralManager.

But, you can still setup the underlying CBCentralManager for state restoration by calling setSharedCentralInstanceWith(restoreIdentifier: ) and use the restoreIdentifier of your choice.

Take note that this method can only be called once and must be called before anything else in the library otherwise the Central sharedInstance will be lazily initiated the first time you access it.

As such, it is recommended to call it in your App Delegate's didFinishLaunchingWithOptions(:)

SwiftyBluetooth.setSharedCentralInstanceWith(restoreIdentifier: "MY_APP_BLUETOOTH_STATE_RESTORE_IDENTIFIER")

Register for state preservation notifications on the default NotificationCenter. Those notifications will contain an array of restored Peripheral.

NotificationCenter.default.addObserver(forName: Central.CentralManagerWillRestoreStateNotification,
                                        object: Central.sharedInstance, 
                                         queue: nil) { (notification) in
    if let restoredPeripherals = notification.userInfo?["peripherals"] as? [Peripheral] {

    }
}

Installation

CocoaPods

Add this to your Podfile:

platform :ios, '9.0'
use_frameworks!

pod 'SwiftyBluetooth'

Then run:

$ pod install

Carthage

Add this to your Cartfile

github "jordanebelanger/SwiftyBluetooth"

Requirements

SwiftyBluetooth requires iOS 9.0+

License

SwiftyBluetooth is released under the MIT License.