CBCentralManager state is Off, even-though the bluetooth is ON - ios

Question

I am trying to check whether the bluetooth is turned on/off with the following code. But it returns CBManagerStatePoweredOff even-though the bluetooth is already on. I checked it in iPhone6s and iOS version 11.2.5(15D60). If i restart bluetooth manually on the settings, It returns CBManagerStatePoweredOn.
- (void)detectBluetooth
{
if(!bluetoothManager)
{
// Put on main queue so we can call UIAlertView from delegate callbacks.
// NSDictionary *options = #{CBCentralManagerOptionShowPowerAlertKey: #NO};
// bluetoothManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil options:options];
bluetoothManager = [[CBCentralManager alloc] initWithDelegate:self queue:dispatch_get_main_queue()];
[bluetoothManager scanForPeripheralsWithServices:nil options:nil];
}
[self centralManagerDidUpdateState:bluetoothManager]; // Show initial state
}
- (void)centralManagerDidUpdateState:(CBCentralManager *)central
{
NSString *stateString = nil;
switch(central.state)
{
case CBManagerStateResetting:
stateString = #"The connection with the system service was momentarily lost, update imminent.";
break;
case CBManagerStateUnsupported:
stateString = #"The platform doesn't support Bluetooth Low Energy.";
break;
case CBManagerStateUnauthorized:
stateString = #"The app is not authorized to use Bluetooth Low Energy.";
break;
case CBManagerStatePoweredOff:
stateString = #"Bluetooth is currently powered off.";
break;
case CBManagerStatePoweredOn:
[self goToSearchDevices];
break;
default: stateString = #"State unknown, update imminent."; break;
}
}