Selection prop is applied for TextInput when component is mounting

Summary:
Changelog: [Internal]
TextInput's predefined "selection" prop is now applied when view did move to window, and when attributed string is set.

Reviewed By: sammy-SC

Differential Revision: D30045271

fbshipit-source-id: e5495171b07a25e1e822421ff1627a8686cd0904

React/Fabric/Mounting/ComponentViews/TextInput/RCTTextInputComponentView.mm

@@ -89,6 +89,7 @@ - (void)didMoveToWindow
     }
     _didMoveToWindow = YES;
   }
+  [self _restoreTextSelection];
 }
 
 #pragma mark - RCTViewComponentView overrides
@@ -525,13 +526,27 @@ - (void)_updateState
   return AttributedString::Range{(int)start, (int)(end - start)};
 }
 
+- (void)_restoreTextSelection
+{
+  const auto selection = std::dynamic_pointer_cast<TextInputProps const>(_props)->selection.get_pointer();
+  if (selection == nullptr) {
+    return;
+  }
+  auto start = [_backedTextInputView positionFromPosition:_backedTextInputView.beginningOfDocument
+                                                   offset:selection->start];
+  auto end = [_backedTextInputView positionFromPosition:_backedTextInputView.beginningOfDocument offset:selection->end];
+  auto range = [_backedTextInputView textRangeFromPosition:start toPosition:end];
+  [_backedTextInputView setSelectedTextRange:range notifyDelegate:YES];
+}
+
 - (void)_setAttributedString:(NSAttributedString *)attributedString
 {
+  if ([self _textOf:attributedString equals:_backedTextInputView.attributedText]) {
+    return;
+  }
   UITextRange *selectedRange = _backedTextInputView.selectedTextRange;
   NSInteger oldTextLength = _backedTextInputView.attributedText.string.length;
-  if (![self _textOf:attributedString equals:_backedTextInputView.attributedText]) {
-    _backedTextInputView.attributedText = attributedString;
-  }
+  _backedTextInputView.attributedText = attributedString;
   if (selectedRange.empty) {
     // Maintaining a cursor position relative to the end of the old text.
     NSInteger offsetStart = [_backedTextInputView offsetFromPosition:_backedTextInputView.beginningOfDocument
@@ -543,6 +558,7 @@ - (void)_setAttributedString:(NSAttributedString *)attributedString
     [_backedTextInputView setSelectedTextRange:[_backedTextInputView textRangeFromPosition:position toPosition:position]
                                 notifyDelegate:YES];
   }
+  [self _restoreTextSelection];
   _lastStringStateWasUpdatedWith = attributedString;
 }