设备方向更改时如何重新排列集合视图单元格

Question

Collection view looks fine when in portrait mode. But when it landscape mode the cells do not rearrange .. they remain in the same place.

I have added autolayout so that the collection view stretches to fill the screen and the collection view has a constant height constraint.

My view hierarchy is like this

View ->ScrollView->ContentView |--> Problematic collection view (one above notifications label) | |-> Tableview (one after after the notifications label) | |->Collection view (black space on top)

The code for the collection view is

-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
return 1;}
-(NSInteger)collectionView:(UICollectionView *)collectionView
numberOfItemsInSection:(NSInteger)section
{
 return 14;
}

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
             cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
if (collectionView==self.offerCollectionView) {
    sliderCollectionInHomeScreen *myCell = [collectionView dequeueReusableCellWithReuseIdentifier:@"reuseIdForSlider"
                                                                                     forIndexPath:indexPath];
    myCell.labelForShopName.text = [[self.arrayForOfferSlider objectAtIndex:indexPath.row] objectForKey:@"shop_name"];
    myCell.labelForOfferName.text = [[self.arrayForOfferSlider objectAtIndex:indexPath.row] objectForKey:@"offer_title"];
    myCell.offerImage.image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[[self.arrayForOfferSlider objectAtIndex:indexPath.row] objectForKey:@"img_url"]]]];

    ;


    return myCell;
}

Answer 1

I don't know if this is correct . But this has worked for me for the time being

-(void) didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrient{

//[self.categoryCollectionView reloadData];
UICollectionViewFlowLayout * lay =[[UICollectionViewFlowLayout alloc] init];
if (UIDeviceOrientationIsLandscape([UIDevice currentDevice].orientation)) {
    [lay setScrollDirection:UICollectionViewScrollDirectionVertical];
}
else{

    [lay setScrollDirection:UICollectionViewScrollDirectionHorizontal];
}


[self.CollectionView setCollectionViewLayout:lay];


}