If you did not have enough time to go through the 50G contents from WWDC'13, I highly recommend you to watch the session 228, aptly named "Hidden Gems in Cocoa and Cocoa Touch".
Links: PDF | Video - SD | Video - HD
There were like 30+ tips, if you are interested my score, it is only 8.
Third year in a row, I published the compiled list of sessions and download links here. Note: You need iOS developer program credentials to download the files.