sortKey property

SemanticsSortKey sortKey

Determines the position of this node among its siblings in the traversal sort order.

This is used to describe the order in which the semantic node should be traversed by the accessibility services on the platform (e.g. VoiceOver on iOS and TalkBack on Android).

Whether this sort key has an effect on the SemanticsNode sort order is subject to how this configuration is used. For example, the absorb method may decide to not use this key when it combines multiple SemanticsConfiguration objects.

Implementation 

SemanticsSortKey get sortKey => _sortKey;
void sortKey= (SemanticsSortKey value)

Implementation 

set sortKey(SemanticsSortKey value) {
  assert(value != null);
  _sortKey = value;
  _hasBeenAnnotated = true;
}