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Comment by alooPotato | Hacker News Reader

I'm shocked how fast the UI is. I'm on an iPhone 4S and every UI gesture, view load and transition has absolutely no lag. For example, from the sliding info sheet, tap on the street view button and it loads instantly.

Even requests that are hitting the server seem to return almost instantly.

Is it just me?

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Looking at the UI I can see why it's fast - everything is set up in a way to maximize performance if you're willing to put in the work.

Which is to say, simple text, simple lines, simple shadows - all of which, so long as you take the time and draw smartly using Core Graphics, is well within the capabilities of any iOS device. Combine with a few dashes of smart UI caching and the whole thing will scream.

iOS UI optimization is a topic I wish more devs knew about. So many relatively simplistic apps are dog slow because no one has bothered to do even the most modest amount of optimization.

We definitely had a blast optimizing the app :) Gotta love Instruments.

Would you care to comment on the perceived lag some people are experiencing while panning and zooming?

Any chance you can do a blog post on your process and what you learnt?

I'll look into it.

tl;dr Use Instruments while running on the device (not the simulator) to pinpoint the highest avoidable CPU usage and then optimize the relevant code. Repeat until the scrolling is buttery smooth on a 3GS :)

It's far from smooth on iPhone 4 and 3GS

Which parts aren't working well for you?

Could I also ask, lots of people are asking about the FPS. I notice the app seems to have zero hiccups/ latency spikes throughout the UI, however the framerate does seem to be around 20/30 FPS in the map view on my iPhone 5. Is this intentional? It is a very consistent framerate it is just that it is noticeably lower than most every other part of the iOS experience.

I'm on an iPhone 4, and panning around is stuttering quite a lot. I'm looking at the downtown Seattle area in particular, if that matters. I'm wondering if the network speed has anything to do with it. I'm using 3G in a heavy urban area, so maybe it's hanging when fetching server data due to network congestion.

Panning around, rotate with 2 fingers, zoom in and out. Even the right menu animation is laggy.

Not sure I agree its simple. They have shadows and subtle transparencies everywhere.

I'm assuming the actual map and StreetView is implemented in openGL. Heck, maybe the whole thing is.

All iOS apps are implemented in OpenGL, since that's what Core Animation wraps.

Do you have any resources you can point to to learn more about iOS UI optimization?

The best resources are from Apple's WWDC:

https://developer.apple.com/videos/wwdc/2012/

Glad to hear :)

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