Fabric: Conversion functions between NSString and std::string

Summary:
@public
Trivial. It's also nice this we have a default encoding now.

Reviewed By: fkgozali

Differential Revision: D8528919

fbshipit-source-id: 0853eca828f22ead1a337fea3d7a2fc9a48e84c8

React/Fabric/Mounting/ComponentViews/View/RCTViewComponentView.mm

@@ -129,8 +129,8 @@ - (void)updateProps:(SharedProps)props
 
   // `nativeId`
   if (oldViewProps.nativeId != newViewProps.nativeId) {
-    self.nativeId = [NSString stringWithCString:newViewProps.nativeId.c_str()
-                                       encoding:NSASCIIStringEncoding];
+    self.nativeId = RCTNSStringFromString(newViewProps.nativeId);
+  }
   }
 }
 
@@ -165,7 +165,7 @@ - (BOOL)accessibilityPerformMagicTap
 
 - (BOOL)didActivateAccessibilityCustomAction:(UIAccessibilityCustomAction *)action
 {
-  _eventEmitter->onAccessibilityAction([action.name cStringUsingEncoding:NSASCIIStringEncoding]);
+  _eventEmitter->onAccessibilityAction(RCTStringFromNSString(action.name));
   return YES;
 }
 

React/Fabric/Mounting/RCTMountingManager.mm

@@ -16,6 +16,7 @@
 #import "RCTMountItemProtocol.h"
 
 #import "RCTCreateMountItem.h"
+#import "RCTConversions.h"
 #import "RCTDeleteMountItem.h"
 #import "RCTInsertMountItem.h"
 #import "RCTRemoveMountItem.h"
@@ -46,8 +47,7 @@ - (void)mutateComponentViewTreeWithMutationInstructions:(facebook::react::TreeMu
   for (auto instruction : instructions) {
     switch (instruction.getType()) {
       case TreeMutationInstruction::Creation: {
-        NSString *componentName = [NSString stringWithCString:instruction.getNewChildNode()->getComponentName().c_str()
-                                                     encoding:NSASCIIStringEncoding];
+        NSString *componentName = RCTNSStringFromString(instruction.getNewChildNode()->getComponentName(), NSASCIIStringEncoding);
         RCTCreateMountItem *mountItem =
           [[RCTCreateMountItem alloc] initWithComponentName:componentName
                                                         tag:instruction.getNewChildNode()->getTag()];
@@ -56,8 +56,7 @@ - (void)mutateComponentViewTreeWithMutationInstructions:(facebook::react::TreeMu
       }
 
       case TreeMutationInstruction::Deletion: {
-        NSString *componentName = [NSString stringWithCString:instruction.getOldChildNode()->getComponentName().c_str()
-                                                     encoding:NSASCIIStringEncoding];
+        NSString *componentName = RCTNSStringFromString(instruction.getOldChildNode()->getComponentName(), NSASCIIStringEncoding);
         RCTDeleteMountItem *mountItem =
           [[RCTDeleteMountItem alloc] initWithComponentName:componentName
                                                         tag:instruction.getOldChildNode()->getTag()];

React/Fabric/RCTConversions.h

@@ -11,6 +11,14 @@
 #import <fabric/graphics/Geometry.h>
 #import <fabric/view/primitives.h>
 
+inline NSString *_Nullable RCTNSStringFromString(const std::string &string, const NSStringEncoding &encoding = NSUTF8StringEncoding) {
+  return [NSString stringWithCString:string.c_str() encoding:encoding];
+}
+
+inline std::string RCTStringFromNSString(NSString *string, const NSStringEncoding &encoding = NSUTF8StringEncoding) {
+  return [string cStringUsingEncoding:encoding];
+}
+
 inline UIColor *_Nullable RCTUIColorFromSharedColor(const facebook::react::SharedColor &sharedColor) {
   return sharedColor ? [UIColor colorWithCGColor:sharedColor.get()] : nil;
 }

React/Fabric/RCTScheduler.mm

@@ -29,7 +29,7 @@ void schedulerDidComputeMutationInstructions(Tag rootTag, const TreeMutationInst
 
   void schedulerDidRequestPreliminaryViewAllocation(ComponentName componentName) override {
     RCTScheduler *scheduler = (__bridge RCTScheduler *)scheduler_;
-    [scheduler.delegate schedulerDidRequestPreliminaryViewAllocationWithComponentName:[NSString stringWithCString:componentName.c_str() encoding:NSASCIIStringEncoding]];
+    [scheduler.delegate schedulerDidRequestPreliminaryViewAllocationWithComponentName:RCTNSStringFromString(componentName, NSASCIIStringEncoding)];
   }
 
 private: