A program logs some message in directory /var/mobile/Containers/Data/Application on iPhone. Is there any way I can get access to this directory without jailbreaking iPhone? If no, is there any directory on iPhone that I can log into and read my logs without jailbreaking?
The answer is
If this is your app, if you connect the device to your computer, you can use the "Devices" option on Xcode's "Window" menu and then download the app's data container to your computer. Just select your app from the list of installed apps, and click on the "gear" icon and choose "Download Container".
Once you've downloaded it, right click on the file in the Finder and choose "Show Package Contents".
Source: Stackoverflow.com