I find that my implementation of the BLE protocol in iOS7 to be very slow in the start up phase. The startup sequence amounts to ~68% of the whole execution time in my app.
What can I do to make it faster?
I've timed it, and here's what I get.
t dt
37.598 [BLE] Discovered peripheral at RSSI -27 with UUID:XYZ
37.599 0.001 [BLE] Connecting to peripheral
37.602 0.003 [BLE] Scanning stopped
37.685 0.083 [BLE] Peripheral connected
38.48 0.795 [BLE] Discovered service
38.599 0.119 [BLE] Discovered characteristic
As you can see there's a huge bottle neck before discovering the service.
My startup code simplified:
- (void)centralManagerDidUpdateState:(CBCentralManager *)central {
switch (central.state) {
case CBCentralManagerStatePoweredOn:
[central scanForPeripheralsWithServices:@[[CBUUID UUIDWithString:kServiceUuid]]
options:@{CBCentralManagerScanOptionAllowDuplicatesKey : @YES}];
break;
case CBCentralManagerStatePoweredOff:
[central stopScan];
break;
default:
break;
}
}
- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI {
if (self.discoveredPeripheral != peripheral) {
self.discoveredPeripheral = peripheral; // Save a local copy of the peripheral, so CoreBluetooth doesn't get rid of it
[central connectPeripheral:peripheral options:nil];
[central stopScan];
}
}
- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral {
[peripheral discoverServices:@[[CBUUID UUIDWithString:kServiceUuid]]];
}
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error {
for (CBService *service in peripheral.services) {
[peripheral discoverCharacteristics:@[array of characteristics]
forService:service];
}
}
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error {
...
}
EDIT
I've learned that similar apps on Android does this ten times faster (making the Android app feel snappier -> better user experience) so I'm curious if it's my implementation, BLE layer or hardware that's the bottleneck. It's tested on an iPhone 4S.