I have been trying for weeks to figure out how state preservation and restoration works for Core Bluetooth in iOS, but I am completely lost.
So far I have done the following:
Added a Restoration Identifier to my CBCentralManager
centralManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil options:#{CBCentralManagerOptionRestoreIdentifierKey:#"myCentralManager"}];
Which should make my application able to call the delegate method:
centralManager:(CBCentralManager *)central
willRestoreState:(NSDictionary *)dict;
In here I am trying to reconnect to my peripheral, if I had a connection prior to the app being suspended, otherwise I will try to scan for my peripheral again, like so:
if (dict[CBCentralManagerRestoredStatePeripheralsKey]) {
for (CBPeripheral *currentPeripheral in peripherals) {
peripheral = currentPeripheral;
}
// Connect to peripheral
}
else{
// Scan for UUID
}
Am I doing this right, am I close, or is this completely wrong?
It works for me now.
I initialize my central manager, just like I did originally, and then in the willRestoreState method, I run the following code:
NSArray* peripherals = [central retrieveConnectedPeripheralsWithServices:[NSArray arrayWithObject:UUID]];
if ([peripherals count] > 0) {
_discoveredPeripheral = [peripherals objectAtIndex:0];
_discoveredPeripheral.delegate= self;
[central connectPeripheral:_discoveredPeripheral options:nil];
} else {
[self scan];
}
Related
I have created two iOS apps; one a Bluetooth LE peripheral that advertises a service, and one a Bluetooth LE central that scans for the advertised service. The peripheral is running on my iPhone5s, and the central is running on my iPad Mini. I initially set the central up to scan for the specific advertised service, but later changed it to listen to any service. In either case, the iPad Mini app acting as a central never detects any advertised service. I am uncertain whether its a problem with the way I setup the peripheral manager to advertise, or if its a problem with the way I setup the central manager to scan, or a device configuration problem. Please offer suggestions or tests I can perform to get this working.
The following is the relevant code for the iPhone5s app acting as a peripheral:
CBPeripheralManager *peripheralManager = [[CBPeripheralManager alloc] initWithDelegate:self queue:nil options:nil];
CBUUID *immediateAlertServiceUUID = [CBUUID UUIDWithString: IMMEDIATE_ALERT_SERVICE_UUID];
CBUUID *alertLevelCharacteristicUUID = [CBUUID UUIDWithString: ALERT_LEVEL_CHARACTERISTIC_UUID];
CBUUID *myCustomCharacteristicUUID = [CBUUID UUIDWithString: MY_CUSTOM_CHARACTERISTIC_UUID];
alertLevelCharacteristic =
[[CBMutableCharacteristic alloc] initWithType:alertLevelCharacteristicUUID
properties:CBCharacteristicPropertyRead
value: nil permissions:CBAttributePermissionsReadable];
myCustomCharacteristic =
[[CBMutableCharacteristic alloc] initWithType:myCustomCharacteristicUUID
properties:CBCharacteristicPropertyRead
value: nil permissions:CBAttributePermissionsReadable];
NSArray *myCharacteristics = #[alertLevelCharacteristic, myCustomCharacteristic];
// Now setup the service
myService = [[CBMutableService alloc] initWithType:immediateAlertServiceUUID primary:YES];
// Finally, associate the characteristic with the service. This is an array of characteristics
myService.characteristics = myCharacteristics;
[peripheralManager addService:myService];
... wait for user to push button to start advertising ...
// Start Advertising
[peripheralManager startAdvertising:#{ CBAdvertisementDataLocalNameKey : #"My Service",
CBAdvertisementDataServiceUUIDsKey : #[myService.UUID] }];
And here are the necessary delegate methods. NOTE: delegate method peripheralManagerDidUpdateState fires and indicates that "CoreBluetooth BLE hardware is powered on and ready" (same is true on the central side). Delegate method peripheralManager:didAddService:error fires without error (see output below). And delegate method peripheralManagerDidStartAdvertising:error fires without an error). Here is the service info printed from didAddService:
<CBMutableService: 0x17008efb0 Primary = YES, UUID = 1802, Included Services = (null), Characteristics = (
"<CBMutableCharacteristic: 0x1702c1500 UUID = 2A06, Value = (null), Properties = 0x2, Permissions = 0x1, Descriptors = (null), SubscribedCentrals = (\n)>",
"<CBMutableCharacteristic: 0x1702c15e0 UUID = 66E613B5-7225-42C6-A9C2-11FADAE62899, Value = (null), Properties = 0x2, Permissions = 0x1, Descriptors = (null), SubscribedCentrals = (\n)>")>
CBPeripheralManager Delegate Methods (sorry for all the code, just trying to be complete.):
- (void)peripheralManagerDidUpdateState:(CBPeripheralManager *)peripheral {
// Determine the state of the peripheral
if ([peripheral state] == CBPeripheralManagerStatePoweredOff) {
NSLog(#"CoreBluetooth BLE hardware is powered off");
}
else if ([peripheral state] == CBPeripheralManagerStatePoweredOn) {
NSLog(#"CoreBluetooth BLE hardware is powered on and ready");
}
else if ([peripheral state] == CBPeripheralManagerStateUnauthorized) {
NSLog(#"CoreBluetooth BLE state is unauthorized");
}
else if ([peripheral state] == CBPeripheralManagerStateUnknown) {
NSLog(#"CoreBluetooth BLE state is unknown");
}
else if ([peripheral state] == CBPeripheralManagerStateUnsupported) {
NSLog(#"CoreBluetooth BLE hardware is unsupported on this platform");
}
}
- (void)peripheralManager:(CBPeripheralManager *)peripheral
didAddService:(CBService *)service
error:(NSError *)error {
if (error) {
NSLog(#"Error publishing service: %#", [error localizedDescription]);
return;
}
else {
NSLog(#"Hurray! Your Service has been successfully published as: %#", service);
}
}
- (void)peripheralManagerDidStartAdvertising:(CBPeripheralManager *)peripheral
error:(NSError *)error {
if (error == nil) {
NSLog(#"Your service is now advertising");
}
else {
NSLog(#"In peripheralManagerDidStartAdvertising: Your service advertising failed with error: %#", error);
}
}
And here is the relevant central code that runs on the iPad Mini:
// Scan for all available CoreBluetooth LE devices
NSArray *services = #[[CBUUID UUIDWithString:IMMEDIATE_ALERT_SERVICE_UUID]];
CBCentralManager *centralManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];
//[centralManager scanForPeripheralsWithServices:services options:nil];
[centralManager scanForPeripheralsWithServices:nil options:nil];
self.centralManager = centralManager;
And here is one of the Central delegate methods. Except for centralManagerDidUpdateState:, none of the delegate methods fire.
// CBPeripheralDelegate - Invoked when you discover the peripheral's available services.
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error
{
NSLog(#"Did Discover Services");
for (CBService *service in peripheral.services) {
[peripheral discoverCharacteristics:nil forService:service];
}
}
// CBCentralManagerDelegate - This is called with the CBPeripheral class as its main input parameter. This contains most of the information there is to know about a BLE peripheral.
- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI
{
NSLog(#"Did Discover Peripheral");
NSString *localName = [advertisementData objectForKey:CBAdvertisementDataLocalNameKey];
if (![localName isEqual:#"My Service"]) {
// We found the Device
[self.centralManager stopScan];
self.myPeripheral = peripheral;
peripheral.delegate = self;
[self.centralManager connectPeripheral:peripheral options:nil];
}
}
As a final note, I question whether BLE even works on my devices. I loaded a couple different iBeacon apps on the iPhone and iPad Mini to see if I can get the two devices to recognize iBeacons (one transmits, one receives), but they did not discover iBeacons either. I also tried with two iPhones. I also turned Bluetooth off then on. I also tried powering the devices off/on. Both devices are running in the foreground. Still no luck. Please help.
I'll concatenate all the comments here:
Using apps like LightBlue or BLE Utility can help you to find if your issue is on the peripheral side or central one, since you're developing both sides yourself.
Before looking for CBServices, you have to connect to a CBPeripheral.
Method that you did show before hand, and seems that it wasn't obvious.
Also, before starting a scan with the CBCentralManager you have to check its state, and it has to be CBPeripheralManagerStatePoweredOn.
I have multiple BLE devices which have same services and characteristics. I can scan and connect multiple devices. After connections, when I try to distinguish each one by sending command it doesn't work. It works perfectly with a single device. Is it something like socket connection ? Like A server spawns child threads and each client can maintain a connection through threads.
Please provide some tips on how to scan each device when other device is reading the data from the device.
-(void) scanDevice {
centralManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];
[centralManager scanForPeripheralsWithServices:nil options:0];
[AppDelegate app].cbCentral = centralManager;
}
-(void) stopScan {
[[AppDelegate app].cbCentral stopScan];
}
-(void)connectToDevice:(CBPeripheral *)peripheral{
[[AppDelegate app] cbCentral].delegate = self;
[[[AppDelegate app] cbCentral] connectPeripheral:peripheral options:nil];
}
-(void)calldiscoverServicesForPeripheral:(CBPeripheral *)peripheral{
[peripheral setDelegate:self];
[peripheral discoverServices:nil];
}
- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral {
NSLog(#"Connected PERIPHERAL %d",peripheral.state);
[delegate getConnectedPeripheral:peripheral];
NSLog(#"Connected peripheral %#",peripheral);
}
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error {
NSLog(#"Discovered servicea: %#", peripheral.services);
for (CBService *service in peripheral.services) {
NSLog(#"Discovered service: %#", [service.UUID data]);
[peripheral discoverCharacteristics:nil forService:service];
}
}
I will explain in detail,
I have table view, that contains BLE devices. For the first time it is empty, so i will search for the devices by calling a class "Scan Devices".
This "Scan devices" class contains all the Corebluetooth methods like CBCentralManager allocation, CBperipheral delegate methods.
After search, I will display the device in table view and connect to the BLE device. I am getting some data from "Scan Device" class.
Now, I want to search more devices to connect and get the data. For this, I will call [[CBCentralManager alloc] initWithDelegate:self] in "ScanDevices" class. At this time, for previous device(connected and reading) is showing the warning "is not a valid peripheral" and new device is connecting and reading data from the device.
But I want read the data from both devices at a time
Please help me...
Thanks
You shouldn't keep creating a new CBCentral - doing so will cause your previous CBCentral to be deallocated and therefore invalidate the existing peripherals.
You should activate your scanning once, say in viewWillAppear and deactivate it in viewWillDisappear.
Once you have initiated scanning and set your delegate in your ScanDevices class, it will call [delegate getConnectedPeripheral:] each time a new peripheral is found and connected.
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:
I added the background mode for centrals.
I always instantiate my central manager with the same unique
identifier.
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.
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];
}
}
}
}
}
I am using Core Bluetooth Framework in my app.
I know how to scan for peripherals and getting values from it.(like Heart Rate Monitor)
But what I want is to retrieve the surrounding iPhone Devices list that supports BLE 4.0 and Bluetooth Enabled ones.
I referred below links..
Uses IOBluetooth Framework
Uses CoreBluetooth For Getting Peripherals not the Devices List
- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI {
// I'm not sure how to make this work
NSLog (#"Discovered peripheral: %#", [peripheral name]);
[self.list addObject:peripheral.name]; // add peripheral name to foundarray
NSLog (#"UUID peripheral: %#", [peripheral UUID]);
NSLog (#"peripheral services before connected: %#", [peripheral services]);
NSLog(#"adversting data %#",[NSString stringWithFormat:#"%#",[advertisementData description]]);
NSLog(#"foundArray is %#", self.list);
}
- (void)centralManagerDidUpdateState:(CBCentralManager *)central {
NSLog(#"Central manager's state is updated to: %#", central);
if(central.state == CBCentralManagerStatePoweredOn)
{
//okay your good to go and can now scan
}
else
{
//Unable to use CentralManager methods so print out the central.state and find out why
}
}
I dont know whether Apple provides this or not..
Any Suggestions or Ideas will be appreciated..
Thank In Advance..
Try below code checkBluetoothAccess and requestBluetoothAccess method
- (void)checkBluetoothAccess {
if(!self.cbManager) {
self.cbManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];
}
/*
We can ask the bluetooth manager ahead of time what the authorization status is for our bundle and take the appropriate action.
*/
CBCentralManagerState state = [self.cbManager state];
if(state == CBCentralManagerStateUnknown) {
[self alertViewWithDataClass:Bluetooth status:NSLocalizedString(#"UNKNOWN", #"")];
}
else if(state == CBCentralManagerStateUnauthorized) {
[self alertViewWithDataClass:Bluetooth status:NSLocalizedString(#"DENIED", #"")];
}
else {
[self alertViewWithDataClass:Bluetooth status:NSLocalizedString(#"GRANTED", #"")];
}
}
- (void)requestBluetoothAccess {
if(!self.cbManager) {
self.cbManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];
}
/*
When the application requests to start scanning for bluetooth devices that is when the user is presented with a consent dialog.
*/
[self.cbManager scanForPeripheralsWithServices:nil options:nil];
}
You can only retrieve the surrounding iOS devices that support Bluetooth 4.0 if they are also advertising a specific service to identify them. You can't just see all iOS devices that are powered on and nearby. If they are advertising, you can just scan for nil and that will return the advertisement packets being seen.
Note: if you care about retrieving BLE devices currently connected from other apps, you can use the retrieveConnectedPeripheralsWithServices: method.
I have multiple BLE devices which have same services and characteristics. I can scan and connect multiple devices. After connections, tried to distinguish each one by sending command but it does not work. It works perfectly with a single device. Is it something like socket connection ? Like A server spawns child threads and each client can maintain a connection through threads. Please provide some tips on how to identity each device.
CBCentralManager instance I created is singleton.
+ (id) sharedInstance
{
static BLEConnectionManager *this = nil;
if (!this) {
this = [[BLEConnectionManager alloc] init];
}
else {
[this scanDevice];
}
return this;
}
-(void) scanDevice {
[centralManager scanForPeripheralsWithServices:nil options:0];
}
- (id) init
{
centralManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];
peripherals = [[NSMutableArray alloc] init];
[centralManager scanForPeripheralsWithServices:nil options:0];
return self;
}
===
EDIT
Is this going to work? After establishing a connection per a device, I am going to create an instance handling service and characteristics in didConnectPeripheral delegation method like temperatureSensor example Apple provide. So each device maintains a connection separately.
- (void) centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral
{
service = [[[LeTemperatureAlarmService alloc] initWithPeripheral:peripheral controller:peripheralDelegate] autorelease];
[service start];
}