feat: proper iOS first renders measurements (#277)

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# Summary

Fixes
#238 on
iOS.

First render on iOS was looking pretty choppy because there was no way
to measure the component on the very first render, because it's still
not defined at that time.
This PR adds a mock text input that gets created as soon as the Shadow
Node is created, gets the initial component's props and is used for
measurements before the real input is defined. After that the mock gets
unmounted (when the real input is finally defined).

## Before vs After

Please play the videos at x0.25 speed to notice the choppiness:

### Before:


https://github.com/user-attachments/assets/69aa524a-5ec1-4fbc-8220-610d2280eaf4

### After:


https://github.com/user-attachments/assets/8f07e5a1-67e5-4c6d-90df-d0b4f44e0f62

## Test Plan

Add a state that toggles input's visibility, with the default visibility
at `false`. Then toggle it and see properly measured component appear
with no intermediate states.

## Compatibility

| OS      | Implemented |
| ------- | :---------: |
| iOS     |    ✅    |
| Android |    ✅(already done)    |

Author: szydlovsky

ios/internals/EnrichedTextInputViewShadowNode.h

@@ -35,6 +35,8 @@ class EnrichedTextInputViewShadowNode : public ConcreteViewShadowNode<
 
     private:
     int localForceHeightRecalculationCounter_;
+    static id mockTextInputView_;
+    void setupMockTextInputView_();
 };
 
 } // namespace facebook::react

ios/internals/EnrichedTextInputViewShadowNode.mm

@@ -8,13 +8,34 @@
 namespace facebook::react {
 
 extern const char EnrichedTextInputViewComponentName[] = "EnrichedTextInputView";
+id EnrichedTextInputViewShadowNode::mockTextInputView_ = nullptr;
 
 EnrichedTextInputViewShadowNode::EnrichedTextInputViewShadowNode(
   const ShadowNodeFragment& fragment,
   const ShadowNodeFamily::Shared& family,
   ShadowNodeTraits traits
 ): ConcreteViewShadowNode(fragment, family, traits) {
   localForceHeightRecalculationCounter_ = 0;
+  
+  // mock text input needs to be initialized on the main thread
+  if([NSThread isMainThread]) {
+    setupMockTextInputView_();
+  } else {
+    dispatch_sync(dispatch_get_main_queue(), ^{
+      setupMockTextInputView_();
+    });
+  }
+}
+
+// mock input is used for the first measure calls that need to be done when the real input isn't defined yet
+void EnrichedTextInputViewShadowNode::setupMockTextInputView_() {
+  // it's rendered far away from the viewport
+  const int veryFarAway = 20000;
+  const int mockSize = 1000;
+  mockTextInputView_ = [[EnrichedTextInputView alloc] initWithFrame:(CGRectMake(veryFarAway, veryFarAway, mockSize, mockSize))];
+  const auto props = this->getProps();
+  ((EnrichedTextInputView *)mockTextInputView_)->blockEmitting = YES;
+  [mockTextInputView_ updateProps:props oldProps:nullptr];
 }
 
 EnrichedTextInputViewShadowNode::EnrichedTextInputViewShadowNode(
@@ -44,6 +65,11 @@
     EnrichedTextInputView *typedComponentObject = (EnrichedTextInputView *) componentObject;
 
     if(typedComponentObject != nullptr) {
+      // remove the mock input on the first render with a defined real input
+      if(mockTextInputView_ != nullptr) {
+        mockTextInputView_ = nullptr;
+      }
+    
       __block CGSize estimatedSize;
 
       // synchronously dispatch to main thread if needed
@@ -61,23 +87,25 @@
       };
     }
   } else {
-    // on the very first call there is no componentView that we can query for the component height
-    // thus, a little heuristic: just put a height that is exactly height of letter "I" with default apple font and size from props
-    // in a lot of cases it will be the desired height
-    // in others, the jump on the second call will at least be smaller
-    const auto props = this->getProps();
-    const auto &typedProps = *std::static_pointer_cast<EnrichedTextInputViewProps const>(props);
-    NSAttributedString *attrStr = [[NSAttributedString alloc] initWithString:@"I" attributes:@{NSFontAttributeName: [UIFont systemFontOfSize:typedProps.fontSize]}];
-    CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attrStr);
-    const CGSize &suggestedSize = CTFramesetterSuggestFrameSizeWithConstraints(
-      framesetter,
-      CFRangeMake(0, 1),
-      nullptr,
-      CGSizeMake(layoutConstraints.maximumSize.width, DBL_MAX),
-      nullptr
-    );
-    
-    return {suggestedSize.width, suggestedSize.height};
+    if(mockTextInputView_ == nullptr) {
+      return Size();
+    }
+  
+    __block CGSize estimatedSize;
+      
+    // synchronously dispatch to main thread if needed
+    if([NSThread isMainThread]) {
+      estimatedSize = [mockTextInputView_ measureSize:layoutConstraints.maximumSize.width];
+    } else {
+      dispatch_sync(dispatch_get_main_queue(), ^{
+        estimatedSize = [mockTextInputView_ measureSize:layoutConstraints.maximumSize.width];
+      });
+    }
+
+    return {
+      estimatedSize.width,
+      MIN(estimatedSize.height, layoutConstraints.maximumSize.height)
+    };
   }
 
   return Size();