UICollectionView and related classes set very flexible and powerful. But once the enhanced flexibility, to some extent, also increased its complexity: UICollectionView deeper than the old UITableView, applicability also stronger. Collection View depth too much, in fact, before Ole Begeman and Ash Furrow had been published in the objc.io Custom Collection View layout and UICollectionView + UIKit mechanics, but I still have not mentioned some of the content they can write. In this article, I assume that you are already familiar with the basic layout UICollectionView, and at least read the wonderful apple Programming Guide and Ole previous article. The first part of this article will focus on examples of how to use the different classes and ways to work together to help achieve some common UICollectionView animation. In the second part, we will look at the view controller with animated transitions and the use of its collection views for transitions in useLayoutToLayoutNavigationTransitions available, if not available, we will implement a custom transition animation. You can find the article mentioned two examples of projects in GitHub: custom collection view layout animation animated transitions Collection View layout Michael Kors Hamilton animation standard UICollectionViewFlowLayout except animation is very easy to customize, Apple chose a safe way to achieve a simple fade animation as animated default all layouts. If you want to implement custom animations, the Michael Kors Satchels best way is to subclass UICollectionViewFlowLayout and achieve your animation in place. Let's go through some examples to understand UICollectionViewFlowLayout subclass some ways on how to help complete the custom animation. Insertion and deletion of elements in general, we layout attributes linear interpolation to calculate the collection view the animation parameters from the initial state to the end state. However, the new insert or delete elements and no initial or final state to be interpolated. To calculate such cells animation, collection view through initialLayoutAttributesForAppearingItemAtIndexPath: to ask its layout object method to get the initial and final attributes: and finalLayoutAttributesForAppearingItemAtIndexPath. Apple's default implementation, for a specific indexPath, returns to its usual position, but the Michael Kors New Arrivals alpha value is 0.0, which produces a fade-in or fade-out animation. If you want a more beautiful effects, such as your new cells emitted from the bottom of the screen and rotate the fly to the corresponding position, you can achieve this layout following subclasses: - (UICollectionViewLayoutAttributes *) initialLayoutAttributesForAppearingItemAtIndexPath: (NSIndexPath *) itemIndexPath {UICollectionViewLayoutAttributes * attr = [self layoutAttributesForItemAtIndexPath: itemIndexPath]; attr.transform = CGAffineTransformRotate (CGAffineTransformMakeScale (0.2, 0.2), M_PI); attr.center = CGPointMake (CGRectGetMidX (self.collectionView.bounds), CGRectGetMaxY (self.collectionView.bounds)) ; return attr;} The results are as follows: the corresponding finalLayoutAttributesForAppearingItemAtIndexPath: method, in addition to setting a different transform, the other is very similar. Response device is rotated device orientation changes often lead to changes in Cheap Michael Kors collection view of bounds. If by shouldInvalidateLayoutForBoundsChange: determining the layout needs to be invalidated and recalculated when layout objects will be asked to provide a new layout. UICollectionViewFlowLayout default implementation to correctly handle this situation, but if you subclass UICollectionViewLayout, you need to return YES when boundary changes: - (BOOL) shouldInvalidateLayoutForBoundsChange: (CGRect) newBounds {CGRect oldBounds = self.collectionView.bounds; if {return YES;} (CGSizeEqualToSize (oldBounds.size, newBounds.size)!) return NO;} changes in the bounds of animation, collection view behave like elements of the current display is removed and then been in the new bounds in reinserted, this will produce a series of each IndexPath finalLayoutAttributesForAppearingItemAtIndexPath: and initialLayoutAttributesForAppearingItemAtIndexPath: calls. If you insert and delete, when added to a very flashy animations, now you should take a look at why Apple judicious use of simple fade animation effect as the default: lol ... To prevent this unwanted animation, initialization position - \u0026 gt ; Deleting movies - \u0026 gt; into a movie - \u0026 gt; final order must exactly match the location of each collection view so that ultimately presents a smooth animation. In other words, finalLayoutAttributesForAppearingItemAtIndexPath: and initialLayoutAttributesForAppearingItemAtIndexPath: should focus on the elements in the end is really in Michael Kors Clutches the display or disappear, or the collection view Michael Kors Christmas Cases is experiencing different situations changed the boundaries of animation, make a different reaction, and return a different layout properties. Fortunately, collection view will tell what kind of layout object animation will be executed. It separately by calling prepareForAnimatedBoundsChange: and prepareForCollectionViewUpdates: bounds to the corresponding elements of change and update. For illustrative purposes of this example, we can use prepareForCollectionViewUpdates: to track updates objects: - (void) prepareForCollectionViewUpdates: (NSArray *) updateItems {[super prepareForCollectionViewUpdates: updateItems]; NSMutableArray * indexPaths = [NSMutableArray array]; for (UICollectionViewUpdateItem * updateItem in updateItems) Christmas Angles iPhone 4 4S Cases {switch (updateItem.updateAction) {case UICollectionUpdateActionInsert: [indexPaths addObject: updateItem.indexPathAfterUpdate]; break; case UICollectionUpdateActionDelete: [indexPaths addObject: updateItem.indexPathBeforeUpdate]; break; case UICollectionUpdateActionMove: [indexPaths Michael Christmas Angles iPhone 5 5S Cases Kors Accessories addObject: updateItem.indexPathBeforeUpdate ]; [indexPaths addObject: updateItem.indexPathAfterUpdate]; break; default: NSLog (@ \u0026 quot; unhandled case:% @ \u0026 quot ;, updateItem); break;}} self.indexPathsToAnimate = indexPaths;} and modify our elements into a movie, Let the element only when it is being inserted into the collection view transmit: - (UICollectionViewLayoutAttributes *) initialLayoutAttributesForAppearingItemAtIndexPath: (NSIndexPath *) itemIndexPath {UICollectionViewLayoutAttributes Christmas Beauty iPhone 5 5S Cases * attr = [self layoutAttributesForItemAtIndexPath: itemIndexPath]; if ([_indexPathsToAnimate containsObject: itemIndexPath]) {attr. transform = CGAffineTransformRotate (CGAffineTransformMakeScale (0.2, 0.2), M_PI); attr.center = CGPointMake (CGRectGetMidX (self.collectionView.bounds), CGRectGetMaxY (self.collectionView.bounds)); [_indexPathsToAnimate removeObject: itemIndexPath];} return attr; } If this element is not being Michael Kors Christmas Beauty iPhone 4 4S Cases Hot Sale inserted, then to return to a normal property by layoutAttributesForItemAtIndexPath, in order to Michael Kors Designer cancel the special appearance animation. Combined finalLayoutAttributesForAppearingItemAtIndexPath: in the corresponding logic will eventually make Michael Kors Handbags elements can change when bounds, from an initial position to a final position in order to achieve a very smooth animation, so as to establish a simple but cool animations: interactive layout Animation Collection views allowing users to interact through gestures and layout to achieve it easy. Such as Apple suggests, as a way to add interactivity to the collection view layout will generally follow the following steps: Create the gesture recognition gesture recognition will add to the collection view the animation through gestures-driven layout Let's see how we can build Michael Kors Bedford & Astor some users Scalable kneading elements, and once the user releases their kneading gesture element returns to its original size. Our approach might look like this: - (void) handlePinch: (UIPinchGestureRecognizer *) sender {if (! [Sender numberOfTouches] = 2) return; if (sender.state == UIGestureRecognizerStateBegan || sender.state == UIGestureRecognizerStateChanged) {// get kneaded point CGPoint p1 = [sender locationOfTouch: 0 inView: [self collectionView]]; CGPoint p2 = [sender locationOfTouch: 1 inView: [self collectionView]]; // calculate the distance expansion CGFloat xd = p1.x - p2.x; CGFloat yd = p1.y - p2.y; CGFloat distance = sqrt (xd * xd + yd * yd); // update the custom layout parameters and invalidation FJAnimatedFlowLayout * layout = (FJAnimatedFlowLayout *) [[ self collectionView] collectionViewLayout]; NSIndexPath * pinchedItem = [self.collectionView indexPathForItemAtPoint: CGPointMake (0.5 * (p1.x + p2.x), 0.5 * (p1.y + p2.y))]; [layout resizeItemAtIndexPath: pinchedItem withPinchDistance : distance]; [layout invalidateLayout];} else if (sender.state == UIGestureRecognizerStateCancelled || sender.state == UIGestureRecognizerStateEnded) {FJAnimatedFlowLayout * layout = (FJAnimatedFlowLayout *) [[self collectionView] collectionViewLayout]; [self.collectionView performBatchUpdates : ^ {[layout resetPinchedItem];} completion: nil];}} This kneading operation needs to calculate the distance and find out the kneaded kneading elements, and notify the user when the kneading layout to achieve self-renewal. When the end of the kneading gesture, the layout will make a return to the original size of the batch update animation. On the other hand, we always track layout kneading elements and the desired size, and provide the correct property in time of need: