Here is the method that I use to update the UI when a background async thread. This is mostly for my own reference:
In one of my recent projects, the need to encode QR codes on the device came up. I tried a few different methods and wasn’t really satisfied with any of them.
The method detailed here is the one I chose based on ease of use and the quick set up time.
The core library is written in c and the base version can be found here: http://fukuchi.org/works/qrencode/index.html.en (download the entire project below).
One of the pieces of code I find myself re-using constantly is creating a gradient background for a UIView in iOS. This example will show two examples of how to create a simple gradient background.
D*Lite is an incremental heuristic search algorithm that is used by agents (game ai, or robots) where the surrounding terrain is not completely known. The algorithm makes assumptions about the unknown terrain. D*Lite finds the shortest route from the start to the goal position, and as it encounters new obstacles these are taken into account and only part of the path is modified. Alternatively, pathfinding algorithms like A* typically have to replan the entire path when the environment changes.