There are lot Apps in App Store which will alllow you transfer and manage folder and files within the App Sandbox. But there is no way to access the entire raw file system of the IOS Devices as this restricted due to accidental deletion of system files.
For Jailbroken Devices, we have iFile in Cydia, which will allow you to access and explore all the file system from the Device. But if you want to access them from other device you need to start the Http server in the iFile. When you start the Http Server it provides a simple Web Interface to manage your IOS file system.
If you ask is there a way to simply access the Raw file from other devices in the same Wifi network, then the answer is YES. By default all the IOS devices has a inbuilt SSH server running at port 22 with default
password : alpine
You can connect to the SSH via Filezilla or any other SFTP Client Tools and start transerring the files to and fro from your Jailbroken device.
Enjoy Transerring files Wirelessly now..
Disclaimer : This is for educational purpose only. I am not recommending to jailbreak or i am not responsible for any damages caused for your device.