You can get the path of an application with [[NSBundle mainBundle] bundlePath]. This method returns: 
/var/mobile/Applications/3204358E-3076-46D7-9E3B-6D4CF021EF5A/myApp.app 
but I need to extract the full path of document directory:
File://localhost/private/var/mobile/Applications/3204358E-3076-46D7-9E3B-6D4CF021EF5E/
Is that File://localhost/private/ is constant ? If no, how can I get this path ?