Animating UICollectionView contentOffset does not display non-visible cells

Question

I\'m working on some ticker-like functionality and am using a UICollectionView. It was originally a scrollView, but we figure a collectionView will make it easier

Answer 1

You could try using a CADisplayLink to drive the animation yourself. This is not too hard to set up since you are using a Linear animation curve anyway. Here's a basic implementation that may work for you:

@property (nonatomic, strong) CADisplayLink *displayLink;
@property (nonatomic, assign) CFTimeInterval lastTimerTick;
@property (nonatomic, assign) CGFloat animationPointsPerSecond;
@property (nonatomic, assign) CGPoint finalContentOffset;

-(void)beginAnimation {
    self.lastTimerTick = 0;
    self.animationPointsPerSecond = 50;
    self.finalContentOffset = CGPointMake(..., ...);
    self.displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(displayLinkTick:)];
    [self.displayLink setFrameInterval:1];
    [self.displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
}

-(void)endAnimation {
    [self.displayLink invalidate];
    self.displayLink = nil;
}

-(void)displayLinkTick {
    if (self.lastTimerTick = 0) {
        self.lastTimerTick = self.displayLink.timestamp;
        return;
    }
    CFTimeInterval currentTimestamp = self.displayLink.timestamp;
    CGPoint newContentOffset = self.collectionView.contentOffset;
    newContentOffset.x += self.animationPointsPerSecond * (currentTimestamp - self.lastTimerTick)
    self.collectionView.contentOffset = newContentOffset;

    self.lastTimerTick = currentTimestamp;

    if (newContentOffset.x >= self.finalContentOffset.x)
        [self endAnimation];
}