The animation is broken in ios8 about thspringycollectionview HOT 1 OPEN

我在6Plus上出现这样的问题，原因在于center位置不对了，我只需要垂直方向。所以我修改了一下：
UIAttachmentBehavior *spring = [[UIAttachmentBehavior alloc] initWithItem:attribute attachedToAnchor:attribute.center];
--->
UIAttachmentBehavior *spring = [[UIAttachmentBehavior alloc] initWithItem:attribute attachedToAnchor:CGPointMake(self.collectionView.bounds.size.width/2, attribute.center.y)];

和：
item.center = center;
--->
item.center = CGPointMake(self.collectionView.bounds.size.width/2, center.y);

from thspringycollectionview.