What a strange article. I'm not sure who this is written for. There's no real details about anything technically interesting that they did other than including the whole messages app codebase in the new app. But explaining how their objects share protocols? Listing some data that they precalculated and the methods it saves them time in? This stuff is obvious to any current ios dev and useless to anyone who isn't an ios dev.
Wha? The UI needs to keep processing events to remain responsive. If you have a long-running (relatively speaking, say 10 milliseconds) process like uncompressing an image, you don't want your UI to lag for that long.
You could have the image decompressor look up every millisecond or so to see if there are any UI events to process, but that leads to the sort of spaghetti code that multithreading/multitasking was built to address.
not sure if you're an obj-c dev but for me the surprise was that it even needed to be mentioned since it's extremely easy and common place to do processing outside of the main thread in current apps.
