Connection device through bluetooth

Question

I'm using ble-plx library to connect to a device through Bluetooth.

I wrote this code but I don't understand why sometimes it fails while other time it works perfectly.

Where is the error which means my code sometimes fails but otherwise works perfectly?

(I am connecting to two devices, so I don't know which one is found first in the scan. ).

scansione1() {
    this.manager.startDeviceScan(null, null, (error, device) => {
      if (error) { 
        // This is used if failed immediately the scan 
        this.manager.stopDeviceScan();
          Alert.alert("Error.")
          Actions.homepageutente()
        return; }
      console.log("Start Scan 1");
      if ((device.name == this.model_dx(this.props.Model)) || (device.name == this.model_sx(this.props.Model))) 
      {
        this.manager.stopDeviceScan();
        this.setState({dispositivo1: device.name})
        // I set this variable device1 because I'll use it in other page. 
        this.setState({device1: device})
        device
          .connect()
          .then( () => {
          console.log("Launch scansione 2")
          this.scansione2();
          })
          .catch(() => {
          //  --> When My connection fails I receive this error <--
          Alert.alert("Connection  bluetooth device 1 not working");
          Actions.homepage();
          });
      }
      else if ((device.name == null )) {
        this.manager.stopDeviceScan();
        this.scansione1();
      } else {
        this.manager.stopDeviceScan();
        Alert.alert("Device " + device.name + " Not find.");
        Actions.homepage();
      }
    });
}

Thank you so much :)

Answer 1

Your code appears to work! Especially as you can connect to the device, but it just takes a couple of attempts. I would check the following things to get rid of your problem.

• trying different devices- this will tell you if the problem is with your connection or the devices you are connecting to.
• replacing the bluetooth chip in your devices or the device you are running the application from - this will give you a fresh start to help troubleshoot your problem.
• report your problems to a device problem to see if others have had similar connection issues.

Alternatively, add a way of retrying to connect after a failure. I would implement that like this:

let i=1;
while (i=1) {  
    if ((device.name == this.model_dx(this.props.Model)) || (device.name == this.model_sx(this.props.Model))) 
        {
            this.manager.stopDeviceScan();
            this.setState({dispositivo1: device.name})
        // I set this variable device1 because I'll use it in other page. 
            this.setState({device1: device})
            device
              .connect()
              .then( () => {
                  console.log("Launch scansione 2")
                  this.scansione2();
                  i++

              })
              .catch(() => {
          //  --> When My connection fails I receive this error <--
              Alert.alert("Connection  bluetooth device 1 not working");
              });
          }
}