Invariant Violation: Native module cannot be null

[empireofryan]

First, thanks for contributing to the up-to-date development of BLE devices, particularly with React Native which makes development all the more accessable for full-stack engineers like myself.

After cloning the SensorTag sample repo, I can't get past the above following error on running the build, which succeeds, but the simulator shows a red screen:

Seems like the error is related to BleManager, which appears on the next error, line 39 of App.js componentDidMount. It's where a new instance of BleManager is instantiated via const manager = new BleManager();. This is after running yarn and in another folding trying with npm install. I then try to run with react-native run-ios. Of note, I had to run react-native upgrade to get over a prior error. I also ran react-native link react-native-ble-plx afterwards just to make sure that was not the issue.

I'm on XCode 10, running the default yarn/package.json bundled within the file.

Any advice is extremely appreciated!

[empireofryan]

Thanks for the repo update!

After cloning the repo, ran yarn and opened the SensorTag.xcodeproj in the ios folder. The simulation successfully built!

Now this screen appears:

And inside the XCode log, the follow log appears and repeats:

2019-01-23 22:44:48.337 [info][tid:main][RCTCxxBridge.mm:216] Initializing <RCTCxxBridge: 0x600003a8c1e0> (parent: <RCTBridge: 0x600002e86610>, executor: (null))
2019-01-23 22:44:48.337981-0500 SensorTag[94000:1636609] Initializing <RCTCxxBridge: 0x600003a8c1e0> (parent: <RCTBridge: 0x600002e86610>, executor: (null))
2019-01-23 22:44:48.408 [info][tid:main][RCTRootView.m:293] Running application SensorTag ({
    initialProps =     {
    };
    rootTag = 1;
})
2019-01-23 22:44:48.408138-0500 SensorTag[94000:1636609] Running application SensorTag ({
    initialProps =     {
    };
    rootTag = 1;
})
2019-01-23 22:44:48.577761-0500 SensorTag[94000:1636977] [] nw_socket_handle_socket_event [C4.1:1] Socket SO_ERROR [61: Connection refused]
2019-01-23 22:44:48.578629-0500 SensorTag[94000:1636977] [] nw_socket_handle_socket_event [C4.2:1] Socket SO_ERROR [61: Connection refused]
2019-01-23 22:44:48.579180-0500 SensorTag[94000:1636987] [] nw_connection_get_connected_socket [C4] Client called nw_connection_get_connected_socket on unconnected nw_connection
2019-01-23 22:44:50.678265-0500 SensorTag[94000:1636984] [] nw_socket_handle_socket_event [C5.1:1] Socket SO_ERROR [61: Connection refused]
2019-01-23 22:44:50.679512-0500 SensorTag[94000:1636984] [] nw_socket_handle_socket_event [C5.2:1] Socket SO_ERROR [61: Connection refused]
2019-01-23 22:44:50.680067-0500 SensorTag[94000:1636980] [] nw_connection_get_connected_socket [C5] Client called nw_connection_get_connected_socket on unconnected nw_connection
2019-01-23 22:44:52.690172-0500 SensorTag[94000:1636980] [] nw_socket_handle_socket_event [C6.1:1] Socket SO_ERROR [61: Connection refused]
2019-01-23 22:44:52.691454-0500 SensorTag[94000:1636980] [] nw_socket_handle_socket_event [C6.2:1] Socket SO_ERROR [61: Connection refused]

I have a iBeacon device on in the proximity. Should this be detectable by a 2017 iMac running the simulator?

[Cierpliwy]

One important thing is that this application is tuned specifically for SensorTag CC 2541. If you want to connect to different device etc. you need to modify source code to do that. In file Saga.js:150 you can see that I'm looking for only for devices with local name set to "SensorTag".

I plan to update, document and create README file which will explain what source code is doing and how you can modify it to play around with the library.

[empireofryan]

Interesting. I never would have guessed that without a README :)

In checking out Saga.js:150, if the conditional to check for "SensorTag" is removed, can other iBeacons be found?

[Cierpliwy]

If you are talking about iBeacons in particular I don't think that this library will help you very much. iOS won't let you access raw advertisement data and will hide most important parameters from you: https://stackoverflow.com/questions/20387327/using-corebluetooth-with-ibeacons. There is a CLLocationManager, which can be used in that situation.