message: Fix the inference guide sample code for the ObjC API
  Fixes
diff: @@ -318,8 +318,12 @@ if (error != nil) { /* Error handling... */ }
  NSMutableData *inputData; // Should be initialized
  // input data preparation...
  +// Get the input `TFLTensor`
  +TFLTensor *inputTensor = [interpreter inputTensorAtIndex:0 error:&error];
  +if (error != nil) { /* Error handling... */ }
  +
  // Copy the input data to the input `TFLTensor`.
  -[interpreter copyData:inputData toInputTensorAtIndex:0 error:&error];
  +[inputTensor copyData:inputData error:&error];
  if (error != nil) { /* Error handling... */ }
  // Run inference by invoking the `TFLInterpreter`.
  