Items blink for center and right section alignment

[Villy21]

Very interesting layout but I found a problem in your example.
I updated in your example generateExampleData function and run on iphone 6.
I see items begin to disappear when big items reach collectionView bottom. This happen when I change section layout with segmented controller to center or right and make some scroll.

• (void)generateExampleData {
  int count=arc4random()%100;
  self.cellSizes = @[].mutableCopy;
  self.cellColors = @[].mutableCopy;

  NSArray* colorsArr = @[[UIColor redColor],
  [UIColor blueColor],
  [UIColor greenColor],
  [UIColor orangeColor],
  [UIColor purpleColor],
  [UIColor yellowColor],
  [UIColor magentaColor],
  [UIColor grayColor],
  ];

  for(int i=0;i<count;i++){
  [self.cellSizes addObject:@(arc4random()%400)];
  [self.cellColors addObject:colorsArr[arc4random()%colorsArr.count]];
  }
  }