This is an example project of how it is possible to mix different techniques into an RSS Reader.
There is always room for improvements.
The UITableView reloadData has to update a lot of cells when all rss feeds are active. It can block the ui thread. I could try to only update relevant cells. However according a simple update on only relevant cells is slower than reloading all data inside the UITableView. If we stack updates for blocks of cells there is a possible performance gain.
The Core Data database will not yet be cleaned. It depends on the purpose of the RSS feed of how long the data should be saved.
Comments are "overused" to demonstrate the use of different techniques. Production code should have less comments and only explain neccesary bits of code.
You can see more improvements in the code source itself. I added TODO statements when there is improvement to be made