cannot find any available serial ports from serialportmanager.availablePorts

[JiahongXue]

I followed the document and trying to figure out what's the port path. Here is what I did:
ORSSerialPortManager *portManager = [ORSSerialPortManager sharedSerialPortManager]; NSArray *availablePorts = portManager.availablePorts; NSLog (@"Available ports are: %lu", (unsigned long)[availablePorts count]);
And it returned 0 in the console.
I used matlab to double check with serailportlist("available"). And it gives me 6 ports.

Any idea what I could go wrong? Also, is there any way I can check if a serial port is connected after I did [serialPort open];?