Animating custom property - objective-c

Question

I'm trying to animate a custom property, and as I've seen on several sources it seems this would be the way to go, but I'm missing something. Here's the CALayer subclass:
#implementation HyNavigationLineLayer
#dynamic offset;
- (instancetype)initWithLayer:(id)layer
{
self = [super initWithLayer:layer];
if (self) {
HyNavigationLineLayer * other = (HyNavigationLineLayer*)layer;
self.offset = other.offset;
}
return self;
}
-(CABasicAnimation *)makeAnimationForKey:(NSString *)key
{
// TODO
return nil;
}
- (id<CAAction>)actionForKey:(NSString *)event
{
if ([event isEqualToString:#"offset"]) {
return [self makeAnimationForKey:event];
}
return [super actionForKey:event];
}
+ (BOOL)needsDisplayForKey:(NSString *)key
{
if ([key isEqualToString:#"offset"]) {
return YES;
}
return [super needsDisplayForKey:key];
}
- (void)drawInContext:(CGContextRef)ctx
{
NSLog(#"Never gets called");
}
#end
I believe this is the only relevant method on my view:
#implementation HyNavigationLineView
+ (Class)layerClass
{
return [HyNavigationLineLayer class];
}
#end
And, finally, in my view controller:
- (void)viewDidLoad
{
[super viewDidLoad];
// Instantiate the navigation line view
CGRect navLineFrame = CGRectMake(0.0f, 120.0f, self.view.frame.size.width, 15.0f);
self.navigationLineView = [[HyNavigationLineView alloc] initWithFrame:navLineFrame];
// Make it's background transparent
self.navigationLineView.backgroundColor = [UIColor colorWithWhite:0.0f alpha:0.0f];
self.navigationLineView.opaque = NO;
[[self.navigationLineView layer] addSublayer:[[HyNavigationLineLayer alloc] init]];
[self.view addSubview:self.navigationLineView];
}
The thing is that the drawInContext method is not called at all, although layerClass is. Am I missing something to make the layer draw?

Answer 1

Solved it. Need to call setNeedsDisplay
- (void)viewDidLoad
{
[super viewDidLoad];
// Instantiate the navigation line view
CGRect navLineFrame = CGRectMake(0.0f, 120.0f, self.view.frame.size.width, 15.0f);
self.navigationLineView = [[HyNavigationLineView alloc] initWithFrame:navLineFrame];
// Make it's background transparent
self.navigationLineView.backgroundColor = [UIColor colorWithWhite:0.0f alpha:0.0f];
self.navigationLineView.opaque = NO;
[[self.navigationLineView layer] addSublayer:[[HyNavigationLineLayer alloc] init]];
[self.view addSubview:self.navigationLineView];
[self.navigationLineView.layer setNeedsDisplay];
}