code: private void scheduleRetryFuture() {
          Log.v(Log.TAG_SYNC, "%s: Failed to xfer; will retry in %d sec", this, RETRY_DELAY_SECONDS);
          synchronized (executor) {
              if (!executor.isShutdown()) {
                  this.retryFuture = executor.schedule(new Runnable() {
                      public void run() {
                          retryIfReady();
                      }
                  }, RETRY_DELAY_SECONDS, TimeUnit.SECONDS);
              }
          }
      }
docs: helper function to schedule retry future. no in iOS code.