Central.m

- (void)centralManagerDidUpdateState:(CBCentralManager *)central {
    if (central.state != CBCentralManagerStatePoweredOn) {
        return;
    }

    [self scan:central];
}

- (void)scan:(CBCentralManager *)central {
    CBUUID *uuid = [CBUUID UUIDWithString:kServiceUUID];
    [central scanForPeripheralsWithServices:@[uuid]
                                options:@{CBCentralManagerScanOptionAllowDuplicatesKey:@YES}];
}