GRMustache: variable tag that expand into a template string

_documentation.md

Documentation of rendering objects: https://github.com/groue/GRMustache/blob/master/Guides/rendering_objects.md

Document.mustache

{{#movie}}
  {{link}}
  {{#director}}
    by {{link}}
  {{/director}}
{{/movie}}

render.m

id data = @{
    @"movie": @{
        @"url": @"/movies/123",
        @"title": @"Citizen Kane",
        @"link": [GRMustache renderingObjectWithBlock:^NSString *(GRMustacheTag *tag, GRMustacheContext *context, BOOL *HTMLSafe, NSError **error) {
            NSString *templateString = @"<a href=\"{{url}}\">{{title}}</a>";
            GRMustacheTemplate *template = [GRMustacheTemplate templateFromString:templateString error:NULL];
            return [template renderContentWithContext:context HTMLSafe:HTMLSafe error:error];
        }],
        @"director": @{
            @"url": @"/people/321",
            @"firstName": @"Orson",
            @"lastName": @"Welles",
            @"link": [GRMustache renderingObjectWithBlock:^NSString *(GRMustacheTag *tag, GRMustacheContext *context, BOOL *HTMLSafe, NSError **error) {
                NSString *templateString = @"<a href=\"{{url}}\">{{firstName}} {{lastName}}</a>";
                GRMustacheTemplate *template = [GRMustacheTemplate templateFromString:templateString error:NULL];
                return [template renderContentWithContext:context HTMLSafe:HTMLSafe error:error];
            }],
        }
    }
}


NSString *rendering = [GRMustacheTemplate renderObject:data
                                          fromResource:@"Document"
                                                bundle:nil
                                                 error:NULL];

rendering.html

<a href="/movies/123">Citizen Kane</a>
by <a href="/people/321">Orson Welles</a>