This repo contains the simple diagnostic app for the headlights.
This app demonstrates a few structures and concepts:
- BLE Router
- MVVM OTA
- Commonality
This structure dynamically distributes BLE Devices to their appropriate views.
The first view where the headlight device was detected and connected to is part of the BLE Router.
struct ContentView: View {
@StateObject private var scanner = BLERouter<Headlight>(scan: [Headlight.SERVICE_UUID], count: 1)
@State var value = 55
var body: some View {
scanner.discovery { devices in
if let first = devices.first {
MainView()
.environmentObject(first)
}
}
}
}The router is completely generic and simple to use, simply provide it a device type, the advertised services to look for, and the number of devices to allow to connect at the same time.
In our case, this app only expects one headlight to be connected at once, so we only use the first device in the list of connected devices.
MainView is dispatched by the router when the device is connected, either by a user action, or an automatic action from user preferences.
- MVVM stands for Model-View View-Model, it is the basis of SwiftUI's design.
- OTA stands for Over the Air
MVVM usually refers to views having access to states and updating themselves based on the changes to these states.
Well... why can't these states be sourced from a BLE peripheral?
So that's what I did, every state has a corresponding BLE characteristic that views can read and write from asynchronously.
This app needs to serialize and deserialize commands just like the embedded devices, but it would be a shame to write all that code again.
So, this app imports a local package called Common that was procedurally generated by the Rust code via an intermediary description language called UDL as part of the uniffi framework.
This means there is a Rust binary embedded into the Swift app, not to mention that Rust binary was extracted from the firmware.
So, when the firmware changes, the app changes accordingly!