Fix EXC_BAD_ACCESS crash when calling payload delegate methods.

Objective-C objects cannot be captured by reference in C++ lambdas and must always be captured by value.

This also takes a copy of the data returned from the Wi-Fi LAN reader, to prevent potential intermittent empty packet issues.

Fixes: #1702
PiperOrigin-RevId: 533925980

connections/swift/NearbyCoreAdapter/Sources/GNCCoreAdapter.mm

@@ -278,13 +278,13 @@ - (void)acceptConnectionRequestFromEndpoint:(NSString *)endpointID
   std::string endpoint_id = [endpointID cStringUsingEncoding:[NSString defaultCStringEncoding]];
 
   PayloadListener listener;
-  listener.payload_cb = [&delegate](absl::string_view endpoint_id, Payload payload) {
+  listener.payload_cb = [delegate](absl::string_view endpoint_id, Payload payload) {
     NSString *endpointID = @(std::string(endpoint_id).c_str());
     GNCPayload *gncPayload = [GNCPayload fromCpp:std::move(payload)];
     [delegate receivedPayload:gncPayload fromEndpoint:endpointID];
   };
   listener.payload_progress_cb =
-      [&delegate](absl::string_view endpoint_id, const PayloadProgressInfo &info) {
+      [delegate](absl::string_view endpoint_id, const PayloadProgressInfo &info) {
         NSString *endpointID = @(std::string(endpoint_id).c_str());
         GNCPayloadStatus status;
         switch (info.status) {

internal/platform/implementation/apple/Mediums/WiFiLAN/GNCWiFiLANSocket.m

@@ -57,7 +57,7 @@ - (NSData *)readMaxLength:(NSUInteger)length error:(NSError **)error {
         }
 #if __LP64__
         // This cast is only safe in a 64-bit runtime.
-        blockResult = (NSData *)content;
+        blockResult = [(NSData *)content copy];
 #else
         blockResult = nil;
 #endif