In the Apple's SwiftUI tutorial 'Scrumdinger', the ScrumTimer model publishes three properties, and the speakers property is not included.
class ScrumTimer: ObservableObject {
/// The name of the meeting attendee who is speaking.
@Published var activeSpeaker = ""
/// The number of seconds since the beginning of the meeting.
@Published var secondsElapsed = 0
/// The number of seconds until all attendees have had a turn to speak.
@Published var secondsRemaining = 0
/// NOTE: This property is not published.
private(set) var speakers: [Speaker] = []
}
But when we click the 'next' button in the MeetingView, the MeetingFooterView gets redrawn.
struct MeetingView: View {
@Binding var scrum: DailyScrum
@StateObject var scrumTimer = ScrumTimer()
private var player: AVPlayer { AVPlayer.sharedDingPlayer }
var body: some View {
ZStack {
RoundedRectangle(cornerRadius: 16)
.fill(scrum.theme.mainColor)
VStack {
MeetingHeaderView(secondsElapsed: scrumTimer.secondsElapsed, secondsRemaining: scrumTimer.secondsRemaining, theme: scrum.theme)
Circle()
.strokeBorder(lineWidth: 24)
MeetingFooterView(speakers: scrumTimer.speakers, skipAction: scrumTimer.skipSpeaker)
// DebugView(speakers: scrumTimer.speakers)
}
}
.padding()
.foregroundColor(scrum.theme.accentColor)
.onAppear {
print("### .onAppear() run")
scrumTimer.reset(lengthInMinutes: scrum.lengthInMinutes, attendees: scrum.attendees)
scrumTimer.speakerChangedAction = {
player.seek(to: .zero)
player.play()
}
scrumTimer.startScrum()
}
.onDisappear {
scrumTimer.stopScrum()
}
.navigationBarTitleDisplayMode(.inline)
}
}
The question is: the MeetingFooterView depends on scrumTimer.speakers, which is an unpublished property, how does it decides to redraw based on whether scrumTimer.speakers has changed?
The complete code can be fetched here.
Thank you.