I need to look my application's database file.I found this question:
How view data stored in Core Data?
In answer he said:
Your app will be folder inside (~ is your home directory):
~/Library/Application Support/iPhone Simulator/User/Applications/
The iPhone Simulator files have moved and can be a bit of a pain to find now. Each simulated device has a folder in ~/Library/Developer/CoreSimulator/Devices. You can root around in there until you find the simulator you're looking for. I wrote a tool to help locate the sandbox for each simulated device on which you've installed an app, but it's not perfect. You can find it here: https://github.com/somegeekintn/SimDirs
There is also an app called SimPholders2 that may be able to help you with this problem - http://simpholders.com/