Non standard URLs in Post - ios

Question

I'm working on an iPhone app that shares data via a custom url scheme. This is working well in email, but I'm having difficulty getting this functionality in Facebook.
I would like to post a link with a callback to my app using my custom url scheme. Basically, I'd like a link that opens the app, if you're running on an iOS device with the app installed.
I'm attempting to do this using properties in a feed dialog, but on calling the dialog I get the error: The post's action links must be valid URLs... It appears that the API does not allow non-standard urls in the properties based on this - is there another way to do this?
SBJSON *jsonWriter = [SBJSON new];
NSDictionary *propertyvalue = [NSDictionary dictionaryWithObjectsAndKeys:#"Final Count", #"text", #"finalcount://somecustomstuffhere", #"href", nil];
NSDictionary *properties = [NSDictionary dictionaryWithObjectsAndKeys:propertyvalue, #"Import ", nil];
NSString *finalproperties = [jsonWriter stringWithObject:properties];
NSString *finalactions = [jsonWriter stringWithObject:actions];
NSMutableDictionary* params = [NSMutableDictionary dictionaryWithObjectsAndKeys:
kAppId, #"app_id",
#"http://itunes.apple.com/us/app/final-count/id532992913?ls=1&mt=8", #"link",
#"http://southwestgecko.com/wp-content/uploads/2012/05/PrimaryIcon#2x.png", #"picture",
#"Final Count", #"name",
#"caption", #"caption",
#"description", #"description",
finalproperties, #"properties",
nil];
[facebook dialog:#"feed" andParams:params andDelegate:self];

Answer 1

This is how I ended up doing it:
I took advantage of the fact that my WordPress based web site will ignore anything after the normal URL, and packed in all the callback data there. The Facebook app is smart enough to forward the full URL string onto the app, and my app is smart enough to ignore the first part of the URL that belongs to the WordPress web site.
This is the link I put into the Facebook post:
link = [NSString stringWithFormat:#"http://southwestgecko.com/?page_id=%i%#",timer.link, [self generateURLFromTimer:timer]];
where the [self generateURLFromTimer:timer] part generates the callback information. This gets put into the dictionary params from the original question under the key #"link". When a URL gets passed into the app, I simply parse out the part pointing to the web site and process the rest as a callback (which in this case includes all the timer information needed to import the timer into my app).