Action.js

Action.prototype = {
    
    run: function(arguments) {
        arguments.completionFunction()
    },
    
    finalize: function(arguments) {
        location.href = "scheme://"
    }
};
    
var ExtensionPreprocessingJS = new Action

ActionRequestHandler.m

@implementation ActionRequestHandler

- (void)beginRequestWithExtensionContext:(NSExtensionContext *)context
{
    BOOL found = NO;

    for (NSExtensionItem *item in context.inputItems) {
        for (NSItemProvider *itemProvider in item.attachments) {
            if ([itemProvider hasItemConformingToTypeIdentifier:(NSString *)kUTTypePropertyList]) {
                [itemProvider loadItemForTypeIdentifier:(NSString *)kUTTypePropertyList options:nil completionHandler:^(NSDictionary *dictionary, NSError *error) {
                    [[NSOperationQueue mainQueue] addOperationWithBlock:^{
                        NSDictionary *resultsDictionary = @{ NSExtensionJavaScriptFinalizeArgumentKey: @{ @"dummyKey" : @"dummyItem" } };
                        NSItemProvider *resultsProvider = [[NSItemProvider alloc] initWithItem:resultsDictionary typeIdentifier:(NSString *)kUTTypePropertyList];
                        
                        NSExtensionItem *resultsItem = [[NSExtensionItem alloc] init];
                        resultsItem.attachments = @[ resultsProvider ];
                        
                        [context completeRequestReturningItems:@[ resultsItem ] completionHandler:nil];
                    }];
                }];
                found = YES;
            }
            break;
        }
        if (found) {
            break;
        }
    }
    
    if (!found) {
        [context completeRequestReturningItems:@[] completionHandler:nil];
    }
}

@end

Thanks.