[ObjC] Add -[GPBMessage mergeFromData:extensionRegistry:error:]

This adds a merge method that doesn't throw, making it generally more usable and allowing usage directly from Swift.

PiperOrigin-RevId: 510490798

objectivec/GPBMessage.h

@@ -278,6 +278,22 @@ CF_EXTERN_C_END
 - (void)mergeFromData:(NSData *)data
     extensionRegistry:(nullable id<GPBExtensionRegistry>)extensionRegistry;
 
+/**
+ * Parses the given data as this message's class, and merges those values into
+ * this message.
+ *
+ * @param data              The binary representation of the message to merge.
+ * @param extensionRegistry The extension registry to use to look up extensions.
+ * @param errorPtr          An optional error pointer to fill in with a failure
+ *                          reason if the data can not be parsed. Will only be
+ *                          filled in if the data failed to be parsed.
+ *
+ * @return Boolean indicating success. errorPtr will only be fill in on failure.
+ **/
+- (BOOL)mergeFromData:(NSData *)data
+    extensionRegistry:(nullable id<GPBExtensionRegistry>)extensionRegistry
+                error:(NSError **)errorPtr;
+
 /**
  * Merges the fields from another message (of the same type) into this
  * message.

objectivec/GPBMessage.m

@@ -965,27 +965,18 @@ static GPBUnknownFieldSet *GetOrMakeUnknownFields(GPBMessage *self) {
            extensionRegistry:(id<GPBExtensionRegistry>)extensionRegistry
                        error:(NSError **)errorPtr {
   if ((self = [self init])) {
-    @try {
-      [self mergeFromData:data extensionRegistry:extensionRegistry];
-      if (errorPtr) {
-        *errorPtr = nil;
-      }
-    } @catch (NSException *exception) {
+    if (![self mergeFromData:data extensionRegistry:extensionRegistry error:errorPtr]) {
       [self release];
       self = nil;
-      if (errorPtr) {
-        *errorPtr = ErrorFromException(exception);
-      }
-    }
 #ifdef DEBUG
-    if (self && !self.initialized) {
+    } else if (!self.initialized) {
       [self release];
       self = nil;
       if (errorPtr) {
         *errorPtr = MessageError(GPBMessageErrorCodeMissingRequiredField, nil);
       }
-    }
 #endif
+    }
   }
   return self;
 }
@@ -2004,6 +1995,27 @@ static GPBUnknownFieldSet *GetOrMakeUnknownFields(GPBMessage *self) {
   }
 }
 
+- (BOOL)mergeFromData:(NSData *)data
+    extensionRegistry:(nullable id<GPBExtensionRegistry>)extensionRegistry
+                error:(NSError **)errorPtr {
+  GPBCodedInputStream *input = [[GPBCodedInputStream alloc] initWithData:data];
+  @try {
+    [self mergeFromCodedInputStream:input extensionRegistry:extensionRegistry];
+    [input checkLastTagWas:0];
+    if (errorPtr) {
+      *errorPtr = nil;
+    }
+  } @catch (NSException *exception) {
+    [input release];
+    if (errorPtr) {
+      *errorPtr = ErrorFromException(exception);
+    }
+    return NO;
+  }
+  [input release];
+  return YES;
+}
+
 #pragma mark - Parse From Data Support
 
 + (instancetype)parseFromData:(NSData *)data error:(NSError **)errorPtr {