Adjusting UICollectionViewFlowLayout cells on rotation

Question

So I'm working on an app that is part of an ePub framework. The app embeds the reader into its view and allows a user to scroll zoom and page by swipe. Im trying to modify it so that the list of ePubs comes into a collectionview as cells displaying the cover image of the epubs. I can create the cells for the flowlayout and using the frame bounds I can create cells but when I try and rotate from portrait to landscape they dont adjust in size and position. My code for the cells is this:

//Set Collection View Cell Size and Orientation
-(CGSize)
    collectionView:(UICollectionView *) collectionView
    layout:(UICollectionViewLayout*)collectionViewLayout
    sizeForItemAtIndexPath:(NSIndexPath *)indexPath{

//Set Landscape size of cells
if(UIDeviceOrientationIsLandscape([UIDevice currentDevice].orientation)){
    CGFloat cellWidth =  [[UIScreen mainScreen] bounds].size.width;
    CGFloat cellHeigt = [[UIScreen mainScreen] bounds].size.height-350;
    NSLog(@"Is Landscape");
    return CGSizeMake(cellWidth, cellHeigt);
}
//Set Potrait size of cells
else{
    NSLog(@"Is Portrait");
    CGFloat cellWidth =  [[UIScreen mainScreen] bounds].size.width-80;
    CGFloat cellHeigt = [[UIScreen mainScreen] bounds].size.height-240;
    return CGSizeMake(cellWidth, cellHeigt);
}
}

and I use this code to position them:

//Collection View Cell Position
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {

if(UIDeviceOrientationIsPortrait([UIDevice currentDevice].orientation)){
     return UIEdgeInsetsMake(0,10,0,20);  // top, left, bottom, right
 }
 else{
     return UIEdgeInsetsMake(0,20,0,20);  // top, left, bottom, right
 }
}

When I rotate the device the cells top boundary goes over the frame.

Please help, how can I update the frame dynamically?

Answer 1

You need to refresh collection while rotation . try following code :

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation
{
    [yourCollectionview performBatchUpdates:nil completion:nil];
}