Getting Bluetooth Device Paired[Technical Questions]

[nick-allen21]

In what area do you have a technical challenge?

Xcode, Simulator & Previews

Description

I am trying to get started with the bluetooth module from Stanford Spezi. I started by defining a device class with a custom UUID and string along with states for the device information and the connect disconnect options. I also my a DeviceInformationService as instructed in the module. I used LightBlue to find and connect to my device and was able to pull a lot of the configuration data that is necessary to connect to the device from there. I've attached that information below.

Then from there I tried to implement the bluetooth module as instructed in Spezi but was not having any luck.
The code is here :

import Spezi
import SpeziBluetooth
import SpeziBluetoothServices
import SwiftUI

class MyDevice: BluetoothDevice, @unchecked Sendable {
    @DeviceState(\.id) var id: UUID
    @DeviceState(\.name) var name: String?
    @DeviceState(\.state) var state: PeripheralState
    
    @Service var deviceInformation = DeviceInformationService()
    
    @DeviceAction(\.connect) var connect
    @DeviceAction(\.disconnect) var disconnect
    
    required init() {}
}

struct DeviceInformationService: BluetoothService {
    static let id: BTUUID = "180A"
    
    @Characteristic(id: "2A29") var manufacturer: String?
    @Characteristic(id: "2A26") var firmwareRevision: String?
}

class BluetoothAppDelegate: SpeziAppDelegate {
        override var configuration: Configuration {
            Configuration {
                Bluetooth {
                    Discover(MyDevice.self, by: .advertisedService("FFB2"))
                }
            }
    }
}

struct PersonView: View {
    @Environment(Bluetooth.self) var bluetooth
    @Environment(MyDevice.self) var myDevice: MyDevice?

    var body: some View {
        List {
            if let myDevice {
                Section {
                    Text("Device")
                    Spacer()
                    Text("\(myDevice.state.description)")
                }
            }

            Section {
                ForEach(bluetooth.nearbyDevices(for: MyDevice.self), id: \.id) { device in
                    Text("\(device.name ?? "unknown")")
                }
            } header: {
                HStack {
                    Text("Devices")
                        .padding(.trailing, 10)
                    if bluetooth.isScanning {
                        ProgressView()
                    }
                }
            }
        }
            .scanNearbyDevices(with: bluetooth, autoConnect: true)
    }
}

#Preview {
    PersonView()
        .environment(MyDevice())
}

And error message is also attatched. it is Fatal Environment+Objects error

Please let me know if you have any ideas?

Reproduction

If you have the bluetooth module installed you should be able to copy and paste this code and see if it can run even if you don't have one of the devices.

Expected behavior

I expected the page to load properly. Furthermore, I want to ensure that I am properly scanning for the right devices in the app so any advice on that (my configuration versus what's in LightBlue) would be greatly appreciated!

Additional context

No response

Code of Conduct

• I agree to follow this course's Code of Conduct and Contributing Guidelines

[PSchmiedmayer]

Thank you for reaching out @nick-allen21!

You will need to run the application on a physical device to test any Bluetooth-related functionality. It won't work on the simulator or preview as the stack there doesn't have access to the macOS bluetooth stack. You can find more instructions how to run the app on your phone here: https://developer.apple.com/documentation/xcode/running-your-app-in-simulator-or-on-a-device.

Happy to use some time in the class today to see how we can work on that and show you how to run the app on your phone.

[nick-allen21]

Hi Paul,

Awesome thank you so much. Yes, I will review this material and then would love if we could spend some time in class working on it.

Best,
Nick

[PSchmiedmayer]

@nick-allen21 Do you mind sharing the solution we found in class here & mark it as an answer for future students & other who might struggle with the same issues?

[nick-allen21]

For sure, just did so below!

[nick-allen21]

Hi All, here is how I ended up getting around the Bluetooth Issue if anyone ends up with the same problem.

Step 1) Add the Spezi Bluetooth module to your Xcode app. You need to download the bluetooth and add it as a dependency. Instructions for this can be found in the Stanford Spezi Bluetooth module

Step 2) Download the app LightBlue. LightBlue allows you to connect to any bluetooth device. Your phone only filters to distinct set of devices that Apple has authorized prior. On LightBlue you will find your device. Once connected, step into the page for your device, and you will see something called an advertised service.

You want to get this advertised service code, which will be the custom UUID that your device sends off. This is how you will filter for you specific device. Get this advertised service UUID.

Step 3) Go to your SpeziAppDelegate. You need to add the following code. anywhere in the Configuration section

Advertised_Service_String = "String from step 1"
...

`
SpeziAppDelegate :
...

Bluetooth {
Discover(MyDevice.self, by: .advertisedService("Advertised_Service_String"))
}
`
This is where the specific advertised service string becomes really important.

Step 4) Go to the info.plist file. Add 'NSBluetoothAlwaysUsageDescription' as a key with the string "This app uses Bluetooth to connect to external devices for enhanced functionality." or something along the likes. This will allow the proper privacy functions for connecting to an external bluetooth device.

Step 5) We are now ready to make our view and find our device.

Create a custom class for your device
`
class MyDevice: BluetoothDevice, @unchecked Sendable, Identifiable {
@DeviceState(.id) var id: UUID
@DeviceState(.name) var name: String?
@DeviceState(.state) var state: PeripheralState

@DeviceAction(\.connect) var connect
@DeviceAction(\.disconnect) var disconnect

required init() {}

}
`
Then create sections for looking for this device

`
import SpeziBluetooth
import SwiftUI

struct MyView: View {
@Environment(Bluetooth.self)
var bluetooth
@Environment(MyDevice.self)
var myDevice: MyDevice?

var body: some View {
    List {
        if let myDevice {
            Section {
                Text("Device")
                Spacer()
                Text("\(myDevice.state.description)")
            }
        }

        Section {
            ForEach(bluetooth.nearbyDevices(for: MyDevice.self), id: \.id) { device in
                Text("\(device.name ?? "unknown")")
            }
        } header: {
            HStack {
                Text("Devices")
                    .padding(.trailing, 10)
                if bluetooth.isScanning {
                    ProgressView()
                }
            }
        }
    }
        .scanNearbyDevices(with: bluetooth, autoConnect: true)
}

}
`

Then when your preview, make sure to inject the device into the environment

#Preview { PersonView() .previewWith { Bluetooth { Discover(MyDevice.self, by: .advertisedService("FFB0")) } } .environment(MyDevice()) }

Step 6) Awesome, now we are ready to test it out. In order to test, we need to use an actual iphone or device. The preview menu does not have access to that part of the stack. I would recommend connecting your iphone to your computer and downloading the app as a developer.