Re: MKMapView: Can't keep annotations from flashing during an update. Ideas?
Re: MKMapView: Can't keep annotations from flashing during an update. Ideas?
- Subject: Re: MKMapView: Can't keep annotations from flashing during an update. Ideas?
- From: Conrad Shultz <email@hidden>
- Date: Wed, 27 Jun 2012 01:11:19 -0700
On Jun 26, 2012, at 7:38 PM, Joe Wollard wrote:
> Out of curiosity, why are you manually removing them in the first place? MKMapView should be handling that logic for you as I understand it. If its for performance, the docs say to make sure you dequeue the MKAnnotationView instead of creating a new one when possible so that it can reuse the views intelligently.
>
> Im working on a problem where I've got around 30-40k annotations on the map and of course performance is terrible when they are all visible at the same time. I'm looking into ways to only drop one pin per x pixels so that fewer pins that are near each other are visible when zoomed out and more pins are visible when zoomed in. If that's similar to the problem you're trying to address, I'd be interested in your findings as I can't seem to come up with anything that doesn't involve a bunch of overhead and rect calculations.
Check out the "Visualizing Information Geographically with MapKit" 2011 WWDC video. I believe it is in one of the demos that one approach to this EXACT issue is presented.
You can also structure your annotations in a manner so as to make finding the right annotation(s) to display in a region easy (or, at least, computationally inexpensive). For example, look at quadtrees (e.g. http://blog.notdot.net/2009/11/Damn-Cool-Algorithms-Spatial-indexing-with-Quadtrees-and-Hilbert-Curves).
--
Conrad Shultz
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