CODEWITHSUNDEEP
iosobjective-cxcodemapkitmkmapview
blue2u
blue2u

Reputation: 61

MapKit iOS rendererForOverlay refreshing out of control

I have a MapKit issue with MKMapView using addOverlay and rendererForOverlay. Testing and debugging is being done on a device (iPhone 7 iOS 11.1.1) with Xcode 9.1 (9B55). The overlay renderer is being refreshed repeatedly for all tiles in the map view (2500 calls per sec to drawMapRect:). The calls to the renderer are ignoring the changed rectangle in setNeedsDisplayInMapRect: and are not initiated by setNeedsDisplayInMapRect. This refreshing continues forever even after all map updates were finished with Xcode reporting the app is using over 160% CPU.

Xcode Debug Navigator Image Link

The MKMapView code is based on the Apple Sample code 'BreadCrumb' available from https://developer.apple.com/library/content/samplecode/Breadcrumb/Introduction/Intro.html. There are no significant structural changes to this code. Has anyone else experienced this or have any suggestions of where to start looking for a solution?

Upvotes: 2

Views: 152

Answers (1)

blue2u
blue2u

Reputation: 61

Running the Apple Breadcrumb sample did not exhibit the same problem. After putting this back into my project and adding the changes from my project I was finally able to isolate the problem to having inserted 'self.alpha = 0.5' into drawMapRect:. It does not matter whether the alpha property is set to 1.0 or some other value, the problem will still occur.

- (void)drawMapRect:(MKMapRect)mapRect
          zoomScale:(MKZoomScale)zoomScale
          inContext:(CGContextRef)context;
{
    CrumbPath *crumbs = (CrumbPath *)(self.overlay);
    self.alpha = 0.5;     //   <-------- THE PROBLEM

With the problem resolved overlay renderer calls reverted to between 40 and 80 per second with no calls occurring without map updates and calls to setNeedsDisplayInMapRect:.

Upvotes: 3

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