fix: render dotted and dashed outlines on iOS views without border radii

packages/react-native/React/Fabric/Mounting/ComponentViews/View/RCTViewComponentView.mm

@@ -1191,7 +1191,10 @@ - (void)invalidateLayer
     _outlineLayer.frame = CGRectInset(
         layer.bounds, -_props->outlineOffset - _props->outlineWidth, -_props->outlineOffset - _props->outlineWidth);
 
-    if (areBorderRadiiCircular(borderMetrics.borderRadii) && borderMetrics.borderRadii.topLeft.horizontal == 0) {
+    // Core Animation can only draw solid contours, so dotted and dashed outlines
+    // have to be drawn with Core Graphics, the same way non-solid borders are.
+    if (_props->outlineStyle == OutlineStyle::Solid && areBorderRadiiCircular(borderMetrics.borderRadii) &&
+        borderMetrics.borderRadii.topLeft.horizontal == 0) {
       UIColor *outlineColor = RCTUIColorFromSharedColor(_props->outlineColor);
       _outlineLayer.borderWidth = _props->outlineWidth;
       _outlineLayer.borderColor = outlineColor.CGColor;

packages/react-native/React/Tests/Mounting/RCTViewComponentViewTests.mm

@@ -9,6 +9,7 @@
 #import <XCTest/XCTest.h>
 #import <react/renderer/components/view/ViewProps.h>
 #import <react/renderer/components/view/ViewShadowNode.h>
+#import <react/renderer/graphics/Color.h>
 
 using namespace facebook::react;
 
@@ -237,4 +238,47 @@ - (void)testViewWithoutRoleIsNotKeyboardFocusable
   XCTAssertFalse(view.canBecomeFocused);
 }
 
+#pragma mark - outline style on square corners (#57841)
+
+static RCTViewComponentView *makeViewWithOutlineStyle(OutlineStyle outlineStyle)
+{
+  RCTViewComponentView *view = [RCTViewComponentView new];
+  view.frame = CGRectMake(0, 0, 100, 100);
+
+  auto props = std::make_shared<ViewProps>();
+  props->outlineWidth = 8;
+  props->outlineColor = colorFromRGBA(255, 165, 0, 255);
+  props->outlineStyle = outlineStyle;
+
+  [view updateProps:props oldProps:ViewShadowNode::defaultSharedProps()];
+  [view finalizeUpdates:RNComponentViewUpdateMaskProps];
+
+  return view;
+}
+
+- (void)testSquareSolidOutlineUsesCoreAnimationBorder
+{
+  // Solid outlines keep the cheaper Core Animation path.
+  RCTViewComponentView *view = makeViewWithOutlineStyle(OutlineStyle::Solid);
+  CALayer *outlineLayer = [view valueForKey:@"_outlineLayer"];
+
+  XCTAssertNotNil(outlineLayer);
+  XCTAssertEqualWithAccuracy(outlineLayer.borderWidth, 8.0, 0.001);
+  XCTAssertNil(outlineLayer.contents);
+}
+
+- (void)testSquareDottedAndDashedOutlinesAreDrawnWithCoreGraphics
+{
+  // A view without border radii used to take the Core Animation path, which can
+  // only render solid contours, so `outlineStyle` was silently dropped.
+  for (OutlineStyle outlineStyle : {OutlineStyle::Dotted, OutlineStyle::Dashed}) {
+    RCTViewComponentView *view = makeViewWithOutlineStyle(outlineStyle);
+    CALayer *outlineLayer = [view valueForKey:@"_outlineLayer"];
+
+    XCTAssertNotNil(outlineLayer);
+    XCTAssertEqualWithAccuracy(outlineLayer.borderWidth, 0.0, 0.001);
+    XCTAssertNotNil(outlineLayer.contents);
+  }
+}
+
 @end

packages/rn-tester/js/examples/View/ViewExample.js

@@ -541,6 +541,33 @@ function BoxShadowExample(): React.Node {
   );
 }
 
+function OutlineStyleExample({
+  outlineStyle,
+  borderRadius,
+  label,
+}: {
+  outlineStyle: 'solid' | 'dashed' | 'dotted',
+  borderRadius: number,
+  label: string,
+}): React.Node {
+  return (
+    <View style={{alignItems: 'center', gap: 8}}>
+      <View
+        style={{
+          width: 50,
+          height: 50,
+          backgroundColor: 'lightgray',
+          borderRadius,
+          outlineWidth: 3,
+          outlineColor: 'purple',
+          outlineStyle,
+        }}
+      />
+      <RNTesterText style={{fontSize: 11}}>{label}</RNTesterText>
+    </View>
+  );
+}
+
 function OutlineExample(): React.Node {
   const defaultStyleSize = {width: 50, height: 50};
 
@@ -665,6 +692,36 @@ function OutlineExample(): React.Node {
           },
         ]}
       />
+      <OutlineStyleExample
+        outlineStyle="solid"
+        borderRadius={0}
+        label="square solid"
+      />
+      <OutlineStyleExample
+        outlineStyle="dashed"
+        borderRadius={0}
+        label="square dashed"
+      />
+      <OutlineStyleExample
+        outlineStyle="dotted"
+        borderRadius={0}
+        label="square dotted"
+      />
+      <OutlineStyleExample
+        outlineStyle="solid"
+        borderRadius={12}
+        label="rounded solid"
+      />
+      <OutlineStyleExample
+        outlineStyle="dashed"
+        borderRadius={12}
+        label="rounded dashed"
+      />
+      <OutlineStyleExample
+        outlineStyle="dotted"
+        borderRadius={12}
+        label="rounded dotted"
+      />
     </View>
   );
 }