Synchronize Text View with Pebble

Question

Is it possible to synchronize a UITextView within an iPhone application with a text layer on my Pebble?

I just want to display a String on a Pebble watch.

Answer 1

This can be done using the AppSync API, which is built on top of AppMessage specifically to provide a system suitable for UI synchronization. The following example is taken from the AppSync section in this official guide and shows the watchapp side of things:

1. To synchronize watch fields, your app needs to declare the input and output buffer sizes in bytes.

   const int inbound_size = 64;
   const int outbound_size = 64;
   app_message_open(inbound_size, outbound_size);
   

2. Prepare the initial values of your data.

   Tuplet initial_values[] = {
     TupletInteger(WEATHER_ICON_KEY, (uint8_t) 1),
     TupletCString(WEATHER_TEMPERATURE_KEY, "42°C"),
   };
   

3. Reserve global memory to store an AppSync struct and your Dictionary.

   #include <...>
   
   AppSync sync;
   uint8_t sync_buffer[32];
   

4. Initialize the synchronization.

   app_sync_init(&sync, sync_buffer, sizeof(sync_buffer),
                 initial_values, ARRAY_LENGTH(initial_values),
                 sync_tuple_changed_callback, sync_error_callback, NULL);
   

5. Process the first and subsequent update.

   void sync_tuple_changed_callback(const uint32_t key,
          const Tuple* new_tuple, const Tuple* old_tuple, void* context)
   {
     // Update your layers
     // Don't forget to call layer_mark_dirty()
   }
   

6. Finally, you can update the value on the watch side. The callback is called when the app has been acknowledged.

   Tuplet new_tuples[] = {
     TupletInteger(WEATHER_ICON_KEY, (uint8_t) 3),
     TupletCString(WEATHER_TEMPERATURE_KEY, "73°C"),
   };
   
   app_sync_set(&sync, new_tuples, 2);
   

I'm not an iOS developer, so I can't help you much on the Objective C side of things, but the article I linked above suggests reading the iOS WeatherDemo app that ships with the SDK for a complete example.