UIScrollView paging with animation - ios

Question

I have achieved the following using UIScrollView and enabled paging.
I want the centre element of the scrollview to show little bigger than other elements. Need to increase/decrease the font of the text label as the scroll view is scrolling depending on its location.
I tried using transform but hard luck.
Code for adding the label's:
array = [[NSMutableArray alloc] init];
for(int i=0;i<10;i++){
UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(x, 0, 150, 50)];
label.text = [NSString stringWithFormat:#"ID - %d",i];
label.textAlignment = UITextAlignmentCenter;
x +=150;
[self.scrollView addSubview:label];
[array addObject:label];
}
[self.scrollView setContentSize:CGSizeMake(x, 50)];
Animation which I performed in ScollViewDidScroll
float position = label.center.x - scrollView.contentOffset.x;
float offset = 2.0 - (fabs(scrollView.center.x - position) * 1.0) / scrollView.center.x;
label.transform = CGAffineTransformIdentity;
label.transform = CGAffineTransformScale(label.transform,offset, offset);
CODE: What I have achieved till now:
https://www.dropbox.com/s/h2q4qvg3n4fi34f/ScrollViewPagingPeeking.zip?dl=0

Answer 1

Don't use scrollview, used UICollectionView and Make collectionView cell bigger as screen size.
And Enable it's paging property than used it's delegate methods.
It's more preferable and efficient way of paging.

Answer 2

It will work using a collection view. Return layout attributes where the transform scale is calculated according to the position. Subclass the UICollectionViewLayout you are using (probably UICollectionViewFlowLayout). To get the resizing based on position to work you should override a few of its methods thusly:
- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds
{
return YES;
}
- (NSArray*)layoutAttributesForElementsInRect:(CGRect)rect
{
NSArray *array = [super layoutAttributesForElementsInRect:rect];
for (UICollectionViewLayoutAttributes *attributes in array)
{
[self updateLayoutAttributesForItemAtIndexPath:layoutAttributes];
}
return array;
}
- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewLayoutAttributes *layoutAttributes = [super layoutAttributesForItemAtIndexPath:indexPath];
[self updateLayoutAttributesForItemAtIndexPath:layoutAttributes];
}
- (UICollectionViewLayoutAttributes *)updateLayoutAttributesScaleForPosition:(UICollectionViewLayoutAttributes *)layoutAttributes
{
// NOTE: Your code assigning an updated transform scale based on the cell position here
return layoutAttributes;
}
Probably the main thing you were missing was the override to the shouldInvalidateLayoutForBoundsChange: method