Apple

On Feb 15, 2012, at 5:30 AM, Bob Frankel wrote:

hi kai,

correct me if i'm wrong, but i believe you need to pass an array of (at least one) service IDs to 'scanForPeripheralsWithServices'.... passing 'nil' will indeed work in the foreground, but not in the background as i understand it....

bob.

On 2/15/2012 2:43 AM, Kai Wang (STC) wrote:

Hi all,

Im using CoreBluetooth framework to discover the BLE device running in pure broadcaster role on iPhone 4S.

The problem is: the code works fine when it runs in the foreground. But the advertisement of the BLE device is not able to discovered when the application is switched to the background (didDiscoverPeripheral is never called). The application comes back to find advertisements when it is switched back from the background to the foreground.

According to the thread How to make BLE app work on background of iPhone4S, it is supported to do scanning in the background. And I did add the background mode entry bluetooth-central to UIBackgroundModes in the apps info.plist. And the code doing scan is as below:

NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:TRUE], CBCentralManagerScanOptionAllowDuplicatesKey, nil];
[self.CM scanForPeripheralsWithServices:nil options:options];

And in the didDiscoverPeripheral delegate, the UI is updated through the code in another class like:

If([NSThread isMainThread] == true) {
[self updateScanningStatus];
}
else {
[NSObject performSelectorOnMainThread:@selector(updateScanningStatus) withObject:nil waitUntilDone:No];
}

Hope someone here could help me to figure the root cause of the problem.

Thanks,
Kai