How to animate collection view vertically with smooth animation

Question

Can any one answer some sample code to animate uicollectionview vertically to the bottom.

dispatch_async(dispatch_get_main_queue(), ^{
            [self.clViewImages reloadData];
             scrolling collection view to bottom

            NSInteger section = [self numberOfSectionsInCollectionView:self.clViewImages] - 1;
            NSInteger item = [self collectionView:self.clViewImages numberOfItemsInSection:section] - 1;
            NSIndexPath *lastIndexPath = [NSIndexPath indexPathForItem:item inSection:section];
            [self.clViewImages scrollToItemAtIndexPath:lastIndexPath atScrollPosition:UICollectionViewScrollPositionBottom animated:YES];
        });

This scrolls my collection view very fast. I want to soft animation section wise. help me find out.

thanks in advance

You are scrolling all the items in collection view in one go, that's why it's fast. So you can scroll to n items that are visible on screen (4-5 items) at a time and then next next n items and so on. In this way it'll we smooth. — Rahul Kumar, Aug 23 '17 at 10:49

score 0 · Answer 1 · answered Aug 23 '17 at 07:27

0

First of all, make sure you set your collection view datasource and delegate like below.

collectionView.datasource = self;
collectionView.delegate = self;

Next thing you have to check that collection Array should not nil.

If all conditions match then try reload your collection view.

[collectionView reloadData];

answered Aug 23 '17 at 07:27

Neha Gupta

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2
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Neha everything is working fine. the issue is I am reloading collection view at the same time animating it to bottom and it is going too fast. is there any solution for this ??? – Vikram Sinha Aug 23 '17 at 07:30

score 0 · Answer 2 · answered Aug 23 '17 at 11:36

This helped me - :

@property (nonatomic, assign) CGPoint scrollingPoint, endPoint;
@property (nonatomic, strong) NSTimer *scrollingTimer;
@property (nonatomic, assign) BOOL animationStarted;

//scroll with finite time interval
- (void)scrollSlowlyWithInterval:(NSNumber*)interval {
    CGFloat height = self.clViewImages.contentSize.height;
    animationStarted = YES;
    // Set the point where the scrolling stops.
    self.endPoint = CGPointMake(0, height-self.clViewImages.frame.size.height);
    // Assuming that you are starting at {0, 0} and scrolling along the x-axis.
    self.scrollingPoint = CGPointMake(0, 0);
    // Change the timer interval for speed regulation.
    self.scrollingTimer = [NSTimer scheduledTimerWithTimeInterval:[interval doubleValue] target:self selector:@selector(scrollSlowlyToPoint) userInfo:nil repeats:YES];
}

- (void)scrollSlowlyToPoint {
    [self.clViewImages setContentOffset:self.scrollingPoint animated:YES];
    // Here you have to respond to user interactions or else the scrolling will not stop until it reaches the endPoint.
    if (CGPointEqualToPoint(self.scrollingPoint, self.endPoint)) {
        [self.scrollingTimer invalidate];
        animationStarted = NO;
    }
    // Going one pixel to the right.
    CGFloat height = [UIScreen mainScreen].bounds.size.height/2;
    self.scrollingPoint = CGPointMake(self.scrollingPoint.x, self.scrollingPoint.y+height);
}

// scrolling to bottom without default animation 
-(void)scrollToBottom{
    NSInteger section = [self.clViewImages numberOfSections] - 1;
    NSInteger items = [self.clViewImages numberOfItemsInSection:section] - 1;
    NSIndexPath *indxPath = [NSIndexPath indexPathForItem:items inSection:section];
    [self.clViewImages scrollToItemAtIndexPath:indxPath atScrollPosition:UICollectionViewScrollPositionBottom animated:YES];
}

-(void)reloadCollectionView{
    dispatch_async(dispatch_get_main_queue(), ^{
        [self.clViewImages reloadData];
        if(!animationStarted){
            [self scrollSlowlyWithInterval:[NSNumber numberWithDouble:0.50f]];
        }
});
}

thanks to Chris

How to animate collection view vertically with smooth animation

2 Answers2