For Google Map You would need to do something like this:-
Use this scheme to request and display directions between two locations. You can also specify the transportation mode.
Parameters
saddr: Sets the starting point for directions searches. This can be a latitude,longitude or a query formatted address. If it is a query string that returns more than one result, the first result will be selected. If the value is left blank, then the user’s current location will be used.
daddr: Sets the end point for directions searches. Has the same format and behavior as saddr.
directionsmode: Method of transportation. Can be set to: driving, transit, bicycling or walking.
An example URL is below to display transit directions between Google NYC and JFK Airport:
comgooglemaps://?saddr=Google+Inc,+8th+Avenue,+New+York,+NY&daddr=John+F.+Kennedy+International+Airport,+Van+Wyck+Expressway,+Jamaica,+New+York&directionsmode=transit

Some additional example are below:
"comgooglemaps://?saddr=Google,+1600+Amphitheatre+Parkway,+Mountain+View,+CA+94043&daddr=Google+Inc,+345+Spear+Street,+San+Francisco,+CA¢er=37.422185,-122.083898&zoom=10"
"comgooglemaps://?saddr=2025+Garcia+Ave,+Mountain+View,+CA,+USA&daddr=Google,+1600+Amphitheatre+Parkway,+Mountain+View,+CA,+United+States¢er=37.423725,-122.0877&directionsmode=walking&zoom=17"
Refer to:
https://developers.google.com/maps/documentation/ios/urlscheme
For Apple Map do like this:-
The following examples show the strings you would use to provide driving directions between San Francisco
and Cupertino:
"http://maps.apple.com/?daddr=San+Francisco,+CA&saddr=cupertino”
Refer:-
"https://developer.apple.com/library/iad/featuredarticles/iPhoneURLScheme_Reference/iPhoneURLScheme_Reference.pdf"
This works for me, only issue i can see with your query is accurate lat long values(Those looks to be a degree latitude longitude value but passed as a decimal latitude longitude value.
Example
Route from Downey to Los Angles
NSString *string = [NSString stringWithFormat:@"http://maps.apple.com/? daddr=%1.6f,%1.6f&saddr=%1.6f,%1.6f",34.0522300,-118.2436800,33.9400100,-118.1325700];

But for some of the directions it does not work and shows Directions not available