Go small with Embedded Swift

3:50 - Empty Embedded Swift application

@_cdecl("app_main")
func app_main() {
  print("🏎️   Hello, Embedded Swift!")
}

6:48 - Turning on LED to blue color

@_cdecl("app_main")
func app_main() {
  print("🏎️   Hello, Embedded Swift!")
  var config = led_driver_get_config()
  let handle = led_driver_init(&config)
  led_driver_set_hue(handle, 240) // blue
  led_driver_set_saturation(handle, 100) // 100%
  led_driver_set_brightness(handle, 80) // 80%
  led_driver_set_power(handle, true)  
}

8:32 - Using an LED object

let led = LED()

@_cdecl("app_main")
func app_main() {
  print("🏎️   Hello, Embedded Swift!")

  led.color = .red
  led.brightness = 80

  while true {
    sleep(1)
    led.enabled = !led.enabled
    if led.enabled {
      led.color = .hueSaturation(Int.random(in: 0 ..< 360), 100)
    }
  }
}

12:44 - Matter application controlling an LED light

let led = LED()

@_cdecl("app_main")
func app_main() {
  print("🏎️   Hello, Embedded Swift!")
  
  // (1) create a Matter root node
  let rootNode = Matter.Node()
  rootNode.identifyHandler = {
    print("identify")
  }
  
  // (2) create a "light" endpoint, configure it
  let lightEndpoint = Matter.ExtendedColorLight(node: rootNode)
  lightEndpoint.configuration = .default
  lightEndpoint.eventHandler = { event in
    print("lightEndpoint.eventHandler:")
    print(event.attribute)
    print(event.value)

    switch event.attribute {
    case .onOff:
      led.enabled = (event.value == 1)
    
    case .levelControl:
      led.brightness = Int(Float(event.value) / 255.0 * 100.0)
    
    case .colorControl(.currentHue):
      let newHue = Int(Float(event.value) / 255.0 * 360.0)
      led.color = .hueSaturation(newHue, led.color.saturation)
    
    case .colorControl(.currentSaturation):
      let newSaturation = Int(Float(event.value) / 255.0 * 100.0)
      led.color = .hueSaturation(led.color.hue, newSaturation)
    
    case .colorControl(.colorTemperatureMireds):
      let kelvins = 1_000_000 / event.value
      led.color = .temperature(kelvins)
    
    default:
      break
    }
  }
  
  // (3) add the endpoint to the node
  rootNode.addEndpoint(lightEndpoint)
  
  // (4) provide the node to a Matter application, start the application
  let app = Matter.Application()
  app.eventHandler = { event in
    print(event.type)
  }
  app.rootNode = rootNode
  app.start()
  
}

18:03 - Reflection example

// Reflection needs metadata records

let mirror = Mirror(reflecting: s)
mirror.children.forEach { … }

struct MyStruct {
  var count: Int
  var name: String
}

18:57 - Unavailable features will produce errors

// Unavailable features will produce errors

protocol Countable {
  var count: Int { get }
}

func count(countable: any Countable) {
  print(countable.count)
}

19:24 - Prefer generics over “any” types

// Prefer generics over “any” types

protocol Countable {
  var count: Int { get }
}

func count(countable: some Countable) {
  print(countable.count)
}