GLKViewControllerDelegate getting blocked

glkit, iphone, mapkit, opengl-es

Solution

The reason for this is that during scrolling in a table view or map view the runloop is in `UITrackingRunLoopMode` which has a higher priority than the default mode. This prevents some events from firing in order to guarantee a high scrolling performance.

To solve your problem you must set up your own rendering loop instead of relying on the `GLKViewController`.

- First set `enableSetNeedsDisplay` of the `GLKView` to `NO` (should be set automatically when using GLKViewController).

- set `preferredFramesPerSecond` to 0 (or maybe 1) to disable the rendering loop of `GLKViewController` or don't use GLKViewController at all

- Import the QuartzCore framework: `#import <QuartzCore/QuartzCore.h>`

- create a `CADisplayLink` and schedule it in `NSRunLoopCommonModes`:

CADisplayLink* displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(render:)];
[displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];

- optional: set the frameInterval of displayLink to 2 (= half the framerate)

- the render method:

- (void)render:(CADisplayLink*)displayLink {
    GLKView* view = (GLKView*)self.view;
    [view display];
}

I haven't tested this, so tell me if it works!

Problem

I have a GLKViewController to handle some OpenGL drawing. I have the `glkView:drawInRect` and `update` method both implemented and have the `preferredFramesPerSecond` property set to 30 (the default). The problem is that the delegate methods stop firing when the user interacts with other part of the app. The two cases that I have seen this happen on is when the user scrolls a UITableView or interacts with a MKMapView. Is there a way to make sure these delegates always fire, regardless of what the rest of the app is doing. The only time I want these to stop is when the app enters the background (which is does automatically).

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