Which is where DebugSearch comes in.
DebugSearch let you do just that; filter messages on the console via a search string. Just build the project (it installs itself as part of the build process), restart XCode, and set your filter by typing this into the console:
From now on, only messages with "some filter" in the string will be displayed in your console.
Try it out! It even works with the latest Xcode 6 beta. Get it from my github.