This guide looks promising for Bluetooth 3.0. Remember that the CoreBluetooth framework is ONLY for Bluetooth Low Energy (4.0). At bluetooth.com’s dev-pages you can see some examples of globally defined services, and as Guan Yang mentionen, you can see that the heart rate service is 0x180D. UUID`s of the unit is defined by the manufacturer.
Here’s a code snippet to maybe help you along the way.
// Initialize a private variable with the heart rate service UUID
CBUUID *heartRate = [CBUUID UUIDWithString:@"180D"];
// Create a dictionary for passing down to the scan with service method
NSDictionary *scanOptions = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:NO] forKey:CBCentralManagerScanOptionAllowDuplicatesKey];
// Tell the central manager (cm) to scan for the heart rate service
[cm scanForPeripheralsWithServices:[NSArray arrayWithObject:heartRate] options:scanOptions]