UIKit Dynamics: Attachment inside UITableViewCell

Question

My table view cells contain a circle in an UIView, indicating a value. I want to add the UIKit Dynamics attachment behaviour to that circle in order to

Answer 1

You can change the anchorPoint of UIAttachmentBehavior during -[scrollViewDidScroll:]. You may refer to the following code snippet:

- (void)viewDidLoad
{
    UIDynamicAnimator *animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];

    UIAttachmentBehavior *behavior1 = [[UIAttachmentBehavior alloc] initWithItem:self.circleView
                                          attachedToAnchor:[self tableViewAnchor]];
    behavior1.length = 10.0;
    behavior1.damping = 0.3;
    behavior1.frequency = 2.5;

    [animator addBehavior:behavior1];
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    behavior1.anchorPoint = [self.tableView convertPoint:[self tableViewAnchor] toView:self.view];
}

- (CGPoint)tableViewAnchor
{
    return CGPointMake(160.0, 154.0);   // return your target coordination w.r.t. the table view
}

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