Question

I’m developing a large scale application for iOS 5 using ARC in xcode. The system seems to work well except for when I’m trying to deallocate one of my interfaces. I’m using a framework called WhirlyGlobe to create a 3D interactive globe in the first view controller.

When I switch view controllers (between the 4 I have), I notice that the memory being used for the view controller with the globe isn’t being released. All the other view controllers (only using simple views and images) release their memory fine – But the globe stays resident, or so it seems. When navigating back to the globe, I get almost a 10mb jump in memory due to 1mb allocations in “glsmLoadTextureLevelBuffer”.

To get on with my question – Is there anything more I can do, with ARC active, to help release my objects? I’ve noticed my viewDidUnload and dealloc methods are not being called at all, and that the only way I can get anything to fire is using viewDidDisappear (which is not ideal obviously) – See below:

- (void)clear
{
[[NSNotificationCenter defaultCenter] removeObserver:self];

if (self.layerThread)
{
    [self.layerThread cancel];
    while (!self.layerThread.isFinished)
        [NSThread sleepForTimeInterval:0.001];
}

self.glView = nil;
self.sceneRenderer = nil;

if (theScene)
{
    delete theScene;
    theScene = NULL;
}
self.theView = nil;
self.texGroup = nil;

self.layerThread = nil;
self.earthLayer = nil;
self.vectorLayer = nil;
self.labelLayer = nil;
self.interactLayer = nil;

self.pinchDelegate = nil;
self.panDelegate = nil;
self.tapDelegate = nil;
self.longPressDelegate = nil;
self.rotateDelegate = nil;
}

- (void)viewDidDisappear:(BOOL)animated {
    NSLog(@"dealloc - viewDidDisappear");
    [self clear];
}

I’m setting everything I no longer need to nil. Is this the best practise?

The globe setup code:
[super viewDidLoad];

AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];

// Set up an OpenGL ES view and renderer
EAGLView *ev = [[EAGLView alloc] initWithFrame:CGRectMake(0, 0, 824, self.view.frame.size.height)];
self.glView = ev;
self.sceneRenderer = [[SceneRendererES1 alloc] init];
UIColor *whiteC = [UIColor whiteColor];
[sceneRenderer setClearColor:whiteC];
glView.renderer = sceneRenderer;
glView.frameInterval = 2;  // 60 fps (2)
[self.view addSubview:glView];
self.view.backgroundColor = [UIColor blackColor];
self.view.opaque = YES;
self.view.autoresizesSubviews = YES;
//glView.frame = self.view.bounds;
glView.frame = CGRectMake(275, GLOBE_HEIGHT_FIX, 768, SCREEN_HEIGHT+STATUS_BAR_HEIGHT); // was 260 x
glView.backgroundColor = [UIColor whiteColor];
self.view.backgroundColor = [UIColor whiteColor]; // red for debug

// Create the textures and geometry, but in the right GL context
[sceneRenderer useContext];

self.texGroup = [[TextureGroup alloc] initWithInfo:[[NSBundle mainBundle] pathForResource:@"bdGlobe_info" ofType:@"plist"]];

// Need an empty scene and view
theScene = new WhirlyGlobe::GlobeScene(4*texGroup.numX,4*texGroup.numY);
self.theView = [[WhirlyGlobeView alloc] init];
[theView setFarPlane:5.0];
[theView setHeightAboveGlobe:GLOBE_HEIGHT_VIEW];
if (globeShouldAnimate) glView.alpha = 1.0;

// Need a layer thread to manage the layers
self.layerThread = [[WhirlyGlobeLayerThread alloc] initWithScene:theScene];

// Earth layer on the bottom
self.earthLayer = [[SphericalEarthLayer alloc] initWithTexGroup:texGroup];
[self.layerThread addLayer:earthLayer];

// Set up the vector layer where all our outlines will go
self.vectorLayer = [[VectorLayer alloc] init];
[self.layerThread addLayer:vectorLayer];

// General purpose label layer.
self.labelLayer = [[LabelLayer alloc] init];
[self.layerThread addLayer:labelLayer];

self.interactLayer = [[InteractionLayer alloc] initWithVectorLayer:self.vectorLayer labelLayer:labelLayer globeView:self.theView
                                                       countryShape:[[NSBundle mainBundle] pathForResource:@"10m_admin_0_map_subunits" ofType:@"shp"]
                                                         oceanShape:[[NSBundle mainBundle] pathForResource:@"10m_geography_marine_polys" ofType:@"shp"]
                                                        regionShape:[[NSBundle mainBundle] pathForResource:@"10m_admin_1_states_provinces_shp" ofType:@"shp"]]; 
self.interactLayer.maxEdgeLen = [self.earthLayer smallestTesselation]/10.0;
[self.layerThread addLayer:interactLayer];

// Give the renderer what it needs
sceneRenderer.scene = theScene;
sceneRenderer.view = theView;

// Wire up the gesture recognizers
self.panDelegate = [PanDelegateFixed panDelegateForView:glView globeView:theView];
self.tapDelegate = [WhirlyGlobeTapDelegate tapDelegateForView:glView globeView:theView];
self.longPressDelegate = [WhirlyGlobeLongPressDelegate longPressDelegateForView:glView globeView:theView];

// Kick off the layer thread
// This will start loading things
[self.layerThread start];

Answer 1

You can use the allocations instrument for this. Using heap shot, you can mark the heap at various points in the lifetime of your application and compare the object graph that constitutes the current allocations in memory at the point of each snapshot. That should help you narrow down what’s being retained and by whom.