Swift: Subscribe to channel

• By default, Broadcast and Presence are enabled for all projects.
• By default, listening to database changes is disabled for new projects due to database performance and security concerns. You can turn it on by managing Realtime's replication.
• You can receive the "previous" data for updates and deletes by setting the table's REPLICA IDENTITY to FULL (e.g., ALTER TABLE your_table REPLICA IDENTITY FULL;).
• Row level security is not applied to delete statements. When RLS is enabled and replica identity is set to full, only the primary key is sent to clients.

Examples

Listen to broadcast messages

let channel = supabase
  .realtime
  .channel("room1")

channel
  .on("broadcast", filter: ChannelFilter(event: "cursor-pos")) \{ message in 
    print("Cursor position received!", message.payload)
  \}
  .subscribe \{ status, error in
    if status == .subscribed \{
      Task \{
        await channel.send(
          type: .broadcast,
          event: "cursor-pos",
          payload: ["x": Double.random(in: 0...1), "y": Double.random(in: 0...1)]
        )
      \}
    \}
  \}

Listen to presence sync

let channel = supabase.realtime.channel("room1")
channel
  .on("presence", filter: ChannelFilter(event: "sync")) \{ _ in
    print("Synced presence state: ", channel.presenceState())
  \}
  .subscribe \{ status, error in
    if status == .subscribed \{
      Task \{
        await channel.track(["online_at": Date().ISO8601Format()])
      \}
    \}
  \}

Listen to presence join

let channel = supabase.realtime.channel("room1")
channel
  .on("presence", filter: ChannelFilter(event: "join")) \{ message in 
    print("Newly joined presences: ", message.payload)
  \}
  .subscribe \{ status, error in
    if status == .subscribed \{
      Task \{
        await channel.track(["online_at": Date().ISO8601Format()])
      \}
    \}
  \}

Listen to presence leave

let channel = supabase.realtime.channel("room1")
channel
  .on("presence", filter: ChannelFilter(event: "leave")) \{ message in 
    print("Newly left presences: ", message.payload)
  \}
  .subscribe \{ status, error in
    if status == .subscribed \{
      Task \{
        await channel.track(["online_at": Date().ISO8601Format()])
        await channel.untrack()
      \}
    \}
  \}

Listen to all database changes

supabase.realtime
  .channel("room1")
  .on("postgres_changes", filter: ChannelFilter(event: "*", schema: "*")) \{ message in
    print("Change received!", message.payload)
  \}
  .subscribe()

Listen to a specific table

supabase.realtime
  .channel("room1")
  .on("postgres_changes", filter: ChannelFilter(event: "*", schema: "public", table: "countries")) \{ message in
    print("Change received!", message.payload)
  \}
  .subscribe()

Listen to inserts

supabase.realtime
  .channel("room1")
  .on("postgres_changes", filter: ChannelFilter(event: "INSERT", schema: "public", table: "countries")) \{ message in
    print("Change received!", message.payload)
  \}
  .subscribe()

Listen to updates

supabase.realtime
  .channel("room1")
  .on("postgres_changes", filter: ChannelFilter(event: "UPDATE", schema: "public", table: "countries")) \{ message in
    print("Change received!", message.payload)
  \}
  .subscribe()

Listen to deletes

supabase.realtime
  .channel("room1")
  .on("postgres_changes", filter: ChannelFilter(event: "DELETE", schema: "public", table: "countries")) \{ message in
    print("Change received!", message.payload)
  \}
  .subscribe()

Listen to multiple events

supabase.realtime
  .channel("room1")
  .on("postgres_changes", filter: ChannelFilter(event: "INSERT", schema: "public", table: "countries"), handler: handleRecordInserted)
  .on("postgres_changes", filter: ChannelFilter(event: "DELETE", schema: "public", table: "countries"), handler: handleRecordDeleted)
  .subscribe()

func handleRecordInserted(_ message: Message) \{
  // handle message
\}

func handleRecordDeleted(_ message: Message) \{
  // handle message
\}

Listen to row level changes

supabase.realtime
  .channel("room1")
  .on(
    "postgres_changes",
    filter: ChannelFilter(
      event: "INSERT",
      schema: "public",
      table: "countries",
      filter: "id=eq.200"
    ),
    handler: handleRecordInserted
  )
  .subscribe()

  func handleRecordInserted(_ message: Message) \{
    // handle message
  \}