central didDiscoverPeripheral: method not invoking

Question

My code:centralManagerDidUpdateState

NSDictionary *opts=[NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:NO],CBCentralManagerScanOptionAllowDuplicatesKey, nil];
[mgr scanForPeripheralsWithServices:nil options:opts];

Then central didDiscoverPeripheral: method not invoking

 [self.peripherals addObject:peripheral];