http://blog.octo.com/en/untar-on-ios-the-pragmatic-way/

• Extract files and directories created with the tar -cf command
• Work with 512 block or multiple (tar -b512 or just tar)

• Extract compressed files and directories created with the tar -czf command
• Work with unix right and ownership
• Work with no standard block size

##How to use

NSData* tarData = [NSData dataWithContentsOfFile:@"/path/to/your/tar/file.tar"];
NSError *error;
[[NSFileManager defaultManager] createFilesAndDirectoriesAtPath:@"/path/to/your/extracted/files/" withTarData:tarData error:&error];

Remember that you can't write outside your app directory