I am going to use iBeacon in my app. Is it possible to write values on it, when the app is opened. If yes how do I achieve this. By using coreBluetooth I can do this.
NSData *bytes = [#"0xDE" dataUsingEncoding:NSUTF8StringEncoding];
[peripheral writeValue:bytes forCharacteristic:characteristic
type:CBCharacteristicWriteWithResponse];
An iBeacon just advertises 3 values; a UUID, a "major" value and a "minor" value.
Beacons typically have some BLE service and characteristics that are used for configuring these and other parameters (such as advertising rate and transmit power) but this is outside of the iBeacon specification; each vendor will have their own service and characteristics.
First you need to know the different between iBeacon(bluetooth beacons) and ordinary Bluetooth device. (You can google it)
The CoreBluetooth function you are calling is for altering values on connected bluetooth peripheral, the keywords are connected bluetooth peripheral which iBeacon is not.
Bluetooth peripherals include GATT server, which allows bluetooth centrals to connect and access its services and characteristics.
While iBeacon just advertises, UUID, major, minor, RSSI. No GATT server, no services or characteristics.
To conclude, there is NO SIMPLE WAY (using bluetooth only) to alter the value ('UUID', 'major', 'minor') on a ORDINARY BEACON.
But some beacon manufacturers do provide some similar solutions, they add extra hardware to beacons (network hard). And provide web portal for beacon owner the control the beacon remotely.
I have developed an app which can modify the iBeacon data of Bluetooth device recently.
There is no standard method in Bluetooth Specification for you to write iBeacon data.
It means that you must use the custom command as you and Bluetooth firmware developer both agree to do this,whatever kind of data communication,different vendor has different methods,both of app developer and Bluetooth firmware developer agree, this is enough!
Related
I have a iBeacon device with services advertising. I need to know to how to connect to the iBeacon from the iOS app in the background mode.
I know the service UUID of the iBeacon but I am not able to scan using serviceUUID in foreground and background mode.
If I scan for nil and filter using the name, working in the foreground but not in the background.
Please help me, I am new to iOS programming. Any ideas?
Don't confuse the ProximityUUID of the iBeacon transmission with a GATT Service UUID. While both are 16 byte identifiers typically represented in the same hex format, the two have entirely different meanings. An iBeacon ProximityUUID cannot be used as a GATT Service UUID.
There is no requirement at all that a bluetooth beacon transmitting an iBeacon frame hosts any connectable GATT services. While some manufacturers do offer a GATT service in their hardware beacons for configuring its identifiers as well as other purposes, the GATT Service UUID is typically not the same as the ProximityUUID.
If you want to do what you describe you need to:
Find out of your beacon manufacturer even hosts a GATT service at all.
It yes, find out what the GATT Service UUID is. Again, it will typically not be the same as the iBeacon ProximityUUID.
If you cannot get the info from the manufacturer, you might be able to find it out by scanning in the foreground (without specifying the GATT Service UUID), then printing out the discovered GATT Service UUIDs for the device that you get by calling discoverServices on the CBPeripheral from the scan results. You may find there are no services, which would give you a no answer to the first question above.
Once you have the above info, you can scan for the beacon in the background by specifying the GATT Service UUID when starting the scan. In the background, you will not get results if you do not specify a GATT Service UUID, and even if you do results will come much more slowly.
We are developing an app which needs to scan for beacons in the background. This requires us for iOS to specify a service UUID while scanning. See Apple documentation:
Apps that have specified the bluetooth-central background mode are allowed to scan while in the background. That said, they must explicitly scan for one or more services by specifying them in the serviceUUIDs parameter. The CBCentralManagerOptionShowPowerAlertKey scan option is ignored while scanning in the background.
We are using a Raspberry Pi with a bluetooth adapter to send a beacon signal (conforming the AltBeacon spec). Unfortunately we are not able to find out how the service UUID should be set in the BLE Advertising PDU, is it part of the Bluetooth specification or part of the Manufacturer specific data structure? We did find examples for setting the service UUID for when you use an iOS device as beacon, but since we are using a generic bluetooth adapter we cannot use that.
Could anyone clarify us how and where the service UUID should be set in the beacon transmission?
is it part of the Bluetooth specification or part of the Manufacturer specific data structure?
the later.
generally when you setting the advertising parameters, you can set the UUID(or name, tx power, etc) to it.
I'm looking to create a BLE Beacon which does not follow Apples iBeacon specification. The reason being that the "beacon" will be an arduino device which the app should also be able to communicate to to instruct it to do things. Is this supported on iOS? I've heard rumours of iOS 8 locking down on generic device advertising via Bluetooth.
Thanks in advance.
Yes, you can do this using the CoreBluetooth APIs, but there are a few restrictions depending on what type of Bluetooth LE advertisement you use.
1. Manufacturer Advertisement
You can read all the bytes of the manufacturer advertisement (up to 24 bytes) using CoreBluetooth, but only when an app is in the foreground. In the background, you will get no callbacks. This is often paired with a second iBeacon advertisement that wakes the app up in the background on iOS. For an example of this type of advertisement, see the AltBeacon specification.
2. GATT Service Advertisement
A GATT service advertisement detection will be sent to an app by CoreBluetooth even when the app is in the background, provided that the app is specifically looking for the GATT service UUID of the beacon. The disadvantage of this approach is that the data payload is generally limited to only 18 bytes after the 2-byte service UUID.
Other Details
In the case of both advertisement types, you can connect to the device using GATT, and read and write data. Note, however, that once you connect the device will generally stop advertising as a beacon.
Both of the above work as described with iOS 8. It's hard to predict the future, but it seems unlikely that Apple will lock down on the above two use cases as they are widely used for Bluetooth LE applications aside from Beacons.
You can see the basic steps to read these advertisements in this blog post. While the post is specifically about how Apple filters out iBeacon advertisements, if you make your own custom manufacturer advertisement, it will allow you to read the bytes as described in the post.
For the sake of completeness, both of the advertisement types above can be picked up by Android devices both in the foreground and the background.
I'd like to ask whether it is possible to access the raw advertisement data from a custom BLE device built using a Raspberry Pi from the Core Bluetooth API?
The use case is to broadcast constantly changed data from the Raspberry Pi to multiple iOS devices in the proximity and consume them in an iOS app. See the topology description in this article.
I already found out that the iBeacon advertisements are filtered out from the Core Bluetooth API and are only accessible from the Core Location API only, which requires the knowledge of the UUID. Due to the constantly changed data a custom iBeacon wouldn't work for this particular use case anyway. But I am unsure whether I could achieve that with Core Bluetooth?
You can do what you want if you change the Raspberry Pi to transmit a non-iBeacon format. CoreBluetooth only filters out the raw bytes of advertisements if they are iBeacon advertisements. See here: Obtaining Bluetooth LE scan response data with iOS
A simple solution is to change your iBeacon advertisement to an open-source AltBeacon advertisement. CoreLocation will no longer pick it up, but CoreBluetooth will.
Here's an example of what you get in the advertisementData NSDictionary in the CoreBluetooth centralManager:didDiscoverPeripheral:advertisementData:RSSI: callback. This example is the result of detecting an AltBeacon advertisement (an open-source beacon standard), with identifiers 2F234454-CF6D-4A0F-ADF2-F4911BA9FFA6 1 2:
{
kCBAdvDataIsConnectable = 0;
kCBAdvDataManufacturerData = <1801beac 2f234454 cf6d4a0f adf2f491 1ba9ffa6 00010002 be00>;
}
You can see how to decode the above bytes by looking at the AltBeacon spec here. Note that the above are the actual contents of the NSDictionary for a detected advertisement on iOS8 that were printed to the console using an NSLog statement.
Quick answer is "there is no direct way".
Why:
Because CoreBluetooth filters out advertisement data, except kCBAdvDataServiceUUIDs, kCBAdvDataLocalName, so there is now way to pass custom data from peripheral to central via advertising.
How can we workaround:
Peripheral
1) Holds some custom service (let's name it 'BeaconService').
2) BeaconService contains Beacon's UUID, major, minor characteristics.
3) Advertises BeaconService UUID (via kCBAdvDataServiceUUIDs key).
Central
1) Scans for peripherals that have BeaconService UUID.
2) Found peripherals are queued.
3) Connection is opened to queued peripherals, and the iBeacon information is read from BeaconService.
4) Read values can be used to start CoreLocation beacon monitoring/ranging.
So by this way you can make bridge from CoreBluetooth to CoreLocation.
For BLE 4.0, it provides API to discover peripherals with array of service UUID.
I just want to find the specific one. How to achieve this ?
If need assign the identifier to the specific device, how to do it ?
(I think my question need some context of core bluetooth of iOS. )
The process for reconnecting to known peripherals is described in the Core Bluetooth Programming Guide.
Essentially if you know the UUID of the device you want to reconnect to (which is the identifier property of the CBPeripheral object) then you can use the retrievePeripheralsWithIdentifiers: method of the CBCentralManager to obtain the CBPeripheral object and then attempt a connection -
NSUUID *pid=[[NSUUID alloc]initWithUUIDString:#"45D956BB-75E4-6CEB-C06C-D531B00174E4" ];
NSArray *peripherals=[self.centralManager retrievePeripheralsWithIdentifiers:#[pid]];
if ([peripherals count]>0)
{
CBPeripheral *peripheral=[peripherals objectAtIndex:0];
peripheral.delegate=self;
[self.connectingPeripherals addObject:peripheral];
NSLog(#"Found peripheral %# with name %#",peripheral.identifier,peripheral.name);
[self.centralManager connectPeripheral:peripheral options:nil];
}
This may not work, and you may have to scan for your peripheral as the identifier of some peripherals (iOS devices in particular) periodically change their UUID.
The programming guide notes -
Note: A peripheral device may not be available to be connected to for
a few reasons. For instance, the device may not be in the vicinity of
the central. In addition, some Bluetooth low energy devices use a
random device address that changes periodically. Therefore, even if
the device is nearby, the address of the device may have changed since
the last time it was discovered by the system, in which case the
CBPeripheral object you are trying to connect to doesn’t correspond to
the actual peripheral device. If you cannot reconnect to the
peripheral because its address has changed, you must rediscover it
using the scanForPeripheralsWithServices:options: method.
You will also have to scan the first time you encounter a peripheral.
Tell me if I'm wrong. You have 2 devices working as central role who wants to connect to one BLE peripheral.
What it is important is the UUID of the services in the BLE peripheral. From your devices in central role you should search peripherals with a wanted UUID Service. Thats all.
To develop with iOS please follow Core Bluetooth Programming Guide. You have a good tutorial there.
As an example of the Apple documentation:
[myCentralManager scanForPeripheralsWithServices:nil options:nil];
In this line of code you can add an Array of UUID objects (CBUUID) instead of nil for scanForPeripheralsWithServices: