CODEWITHSUNDEEP
iosswiftcore-bluetooth
dmerr
dmerr

Reputation: 132

CoreBluetooth peripheral.setNotifyValue(true, characteristic) is not notifying

I have two programs, one for Mac and one for iOS. When I connect to the iOS device from the Mac, it finds the services I want, and the characteristics I want. After finding the characteristic, I use peripheral.setNotifyValue(true, forCharacteristic: characteristic), but the peripheralManager:central:didSubscribeToCharacteristic: method isn't being called on the iOS side. When I check if characteristic.isNotifying it is false. From what I understand when I set the notify value to true, it should be notifying, and whenever i change the value is updates. Why is it not updating? Thanks in advance.

Here is the code that sets up the characteristic in question - 

self.characteristic = CBMutableCharacteristic(type: UUID_CHARACTERISTIC, properties: CBCharacteristicProperties.Read, value: self.dataToSend, permissions: CBAttributePermissions.Readable) 
theService = CBMutableService(type: UUID_SERVICE, primary: true)
theService.characteristics = [characteristic]
self.peripheralManager.addService(theService)

Upvotes: 1

Views: 4947

Answers (1)

Paulw11
Paulw11

Reputation: 115051

If you want your characteristic to support notify operations then you need to set this on its properties -

self.characteristic = CBMutableCharacteristic(type: UUID_CHARACTERISTIC, properties: CBCharacteristicProperties.Read|CBCharacteristicProperties.Notifiy, value: self.dataToSend, permissions: CBAttributePermissions.Readable);

An attempt to set notification on a characteristic that doesn't state support for notification is ignored by Core Bluetooth.

Also, be aware that by setting a value when the characteristic is created, you will not be able to change the value of this characteristic in the future - therefore notification is somewhat pointless. If you want to be able to change the value you must specify nil for value when you create the characteristic.

From the CBMutableCharacteristic documentation -

Discussion

If you specify a value for the characteristic, the value is cached and its properties and permissions are set to CBCharacteristicPropertyRead and CBAttributePermissionsReadable, respectively. Therefore, if you need the value of a characteristic to be writeable, or if you expect the value to change during the lifetime of the published service to which the characteristic belongs, you must specify the value to be nil. So doing ensures that the value is treated dynamically and requested by the peripheral manager whenever the peripheral manager receives a read or write request from a central. When the peripheral manager receives a read or write request from a central, it calls the peripheralManager:didReceiveReadRequest: or the peripheralManager:didReceiveWriteRequests: methods of its delegate object, respectively.

Upvotes: 1

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