Facebook Applinks - pass custom JSON data in al_applink_data - json

Question

is it possible to pass custom data in al_applink_data using Facebook applinks?
I can retrieve this JSON example but I cannot see a place where to append my custom data to it. If this is not possible than my only solution is to parse obtained URL but this doesn't seem much bulletproof.
{
"target_url": "https://www.example.com/abc.html",
"extras": {
"fb_app_id": [YOUR_FACEBOOK_APP_ID],
"fb_access_token": "[ACCESS_TOKEN']",
"fb_expires_in": "3600"
},
"referer_app_link": {
"url": "[FACEBOOK_APP_BACK_LINK]",
"app_name": "Facebook"
}
}

Answer 1

Parsing Data
My solution by creating custom data for target_url.
NSDictionary *dictionary = #{ #"target_url" : #"YOUR_VALUE"};
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dictionary options:0 error:nil];
NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
Then, append with your Facebook app link ID with al_applink_data key in FB Graph Object dictionary.
[NSString stringWithFormat:#"https://fb.me/FB_LINK_ID?al_applink_data=%#", jsonString]
That's it.!!
Retrieving Callback URL
if([[call appLinkData] targetURL] != nil)
{
NSURL *targetUrl = [[call appLinkData] targetURL];
//Actual URL
NSString *urlString = [[targetUrl absoluteString] stringByRemovingPercentEncoding];
URLParser *parser = [[URLParser alloc] initWithURLString:urlString];
//Fetching value for 'al_applink_data'
NSString *appLinkData = [parser valueForVariable:#"al_applink_data"];
NSData *objectData = [appLinkData dataUsingEncoding:NSUTF8StringEncoding];
//Dictionary with 'target_key' key and its value.
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:objectData options:NSJSONReadingMutableContainers error:nil];
NSLog(#"%#", json);
}
Reference for URL parsing : URLParser
Thanks.

Answer 2

The "extras" map was designed to carry arbitrary metadata. What type of custom data do you need? Passing of custom data through the "extras" blob requires the caller to know something about your app (so they can actually add the data).