Ios UIDynamicAnimator+;导致永久圆周运动的自定义UICollectionViewLayout
我一直在复制2013年WWDC会议217“探索iOS 7上的滚动视图”。我使用的是Xcode 7 beta 2,我的项目仅限于iOS 9 我正在尝试将Ios UIDynamicAnimator+;导致永久圆周运动的自定义UICollectionViewLayout,ios,swift,uicollectionview,uicollectionviewlayout,uidynamicanimator,Ios,Swift,Uicollectionview,Uicollectionviewlayout,Uidynamicanimator,我一直在复制2013年WWDC会议217“探索iOS 7上的滚动视图”。我使用的是Xcode 7 beta 2,我的项目仅限于iOS 9 我正在尝试将UIDynamicAnimator与我的UICollectionViewLayout一起使用,其方式与会话217中的方式类似,以模仿Messages.app feel。我的UICollectionViewLayout是一个自定义布局,出于某种原因,在我的项目中,我的单元格似乎以圆周运动方式反弹 这是我的自定义布局代码 // Didn't write
UIDynamicAnimator
与我的UICollectionViewLayout
一起使用,其方式与会话217中的方式类似,以模仿Messages.app feel。我的UICollectionViewLayout
是一个自定义布局,出于某种原因,在我的项目中,我的单元格似乎以圆周运动方式反弹
这是我的自定义布局代码
// Didn't write this code myself, but should be pretty simple to follow. @Goles
#import "VVSpringCollectionViewFlowLayout.h"
@interface VVSpringCollectionViewFlowLayout()
@property (nonatomic, strong) UIDynamicAnimator *animator;
@end
@implementation VVSpringCollectionViewFlowLayout
-(id)init {
if (self = [super init]) {
_springDamping = 0.5;
_springFrequency = 0.8;
_resistanceFactor = 500;
}
return self;
}
- (id)initWithCoder:(nonnull NSCoder *)aDecoder {
self = [super initWithCoder:aDecoder];
if (self) {
_springDamping = 0.5;
_springFrequency = 0.8;
_resistanceFactor = 500;
}
return self;
}
-(void)prepareLayout {
[super prepareLayout];
if (!_animator) {
_animator = [[UIDynamicAnimator alloc] initWithCollectionViewLayout:self];
CGSize contentSize = [self collectionViewContentSize];
NSArray *items = [super layoutAttributesForElementsInRect:CGRectMake(0, 0, contentSize.width, contentSize.height)];
for (UICollectionViewLayoutAttributes *item in items) {
UIAttachmentBehavior *spring = [[UIAttachmentBehavior alloc] initWithItem:item attachedToAnchor:item.center];
spring.length = 0;
spring.damping = self.springDamping;
spring.frequency = self.springFrequency;
[_animator addBehavior:spring];
}
}
}
-(NSArray *)layoutAttributesForElementsInRect:(CGRect)rect {
return [_animator itemsInRect:rect];
}
- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath {
return [_animator layoutAttributesForCellAtIndexPath:indexPath];
}
-(BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds {
UIScrollView *scrollView = self.collectionView;
CGFloat scrollDelta = newBounds.origin.y - scrollView.bounds.origin.y;
CGPoint touchLocation = [scrollView.panGestureRecognizer locationInView:scrollView];
for (UIAttachmentBehavior *spring in _animator.behaviors) {
CGPoint anchorPoint = spring.anchorPoint;
CGFloat distanceFromTouch = fabs(touchLocation.y - anchorPoint.y);
CGFloat scrollResistance = distanceFromTouch / self.resistanceFactor;
id<UIDynamicItem> item = [spring.items firstObject];
CGPoint center = item.center;
if (scrollDelta > 0) {
center.y += MIN(scrollDelta, scrollDelta * scrollResistance);
}
item.center = center;
[_animator updateItemUsingCurrentState:item];
}
return NO;
}
@end
我错过了什么?(在其他项目中尝试了这种精确的布局,并且似乎有效)
编辑:
我上传了一个示例项目(已删除),自定义集合视图布局类名为VVSpringCollectionViewFlowLayout.m
,我自己没有太多时间来研究这个问题,因为我最近有很多工作要做
当示例项目运行(Xcode 7 beta版或更高版本)时,系统会提示您使用滑块,一直向右拖动以可视化集合视图单元格。下面的代码将帮助您指出/指出正确的方向。它还有一些额外的功能,比如清理不必要的动画师行为(如果不在视图中),跟踪触摸,以便从该点开始动画师的行为。从一个旧项目中剥离出来,因此应该可以正常工作。包含演示创建视频的Github示例项目-
嗯,公认的答案基本上是正确的。实际上,在屏幕刻度为3的iPhone+上,它可能会再次出现同样的故障症状。以1/3或2/3点的无理数拉动中心将再次导致永久圆周运动 四舍五入为偶数
2.0*floorf((数字/2.0)+0.5)
-从另一篇文章中修改。
这将确保中心是整数,而不是无理的。
然后,只在一个维度中拖动中心,将使bug消失。Hi,这里有一个指向最小项目的链接,显示类按预期工作,该项目实际上没有编译,但无论如何。。。出于某种原因,我在我的项目中看到了上述行为。这并没有回答原来的问题。。。我可能会继续发布一个小样本项目来揭示这个问题。嘿,不知道为什么不在你的系统上编译。这里是一个5分钟的视频,从零开始创建项目。也许你会发现一些东西。在我的项目中,我尝试了几种不同的方法,比如滴答声、水平反弹等,但还不能重现您的问题。如果能直接看到这个问题,一个示例项目就太好了。嘿,Dave,我将提供一个示例项目;)@天哪,我已经修好了。看看我的示例项目(+CocoaPods)
center.y += MIN(scrollDelta, scrollDelta * scrollResistance);
@interface VVSpringCollectionViewFlowLayout ()
@property (nonatomic, strong) UIDynamicAnimator *dynamicAnimator;
@property (nonatomic, strong) NSMutableSet *visibleIndexPathsSet;
@property (nonatomic, assign) CGFloat latestDelta;
@end
@implementation VVSpringCollectionViewFlowLayout
- (id)init {
if (self = [super init]) {
self.dynamicAnimator = [[UIDynamicAnimator alloc] initWithCollectionViewLayout:self];
self.visibleIndexPathsSet = [NSMutableSet set];
}
return self;
}
- (id)initWithCoder:(nonnull NSCoder *)aDecoder {
if (self = [super initWithCoder:aDecoder]) {
self.dynamicAnimator = [[UIDynamicAnimator alloc] initWithCollectionViewLayout:self];
self.visibleIndexPathsSet = [NSMutableSet set];
}
return self;
}
-(NSArray *)layoutAttributesForElementsInRect:(CGRect)rect {
return [self.dynamicAnimator itemsInRect:rect];
}
-(UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath {
return [self.dynamicAnimator layoutAttributesForCellAtIndexPath:indexPath];
}
- (UICollectionViewLayoutAttributes *)layoutAttributesForSupplementaryViewOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath {
return [self.dynamicAnimator layoutAttributesForSupplementaryViewOfKind:kind atIndexPath:indexPath];
}
-(void)prepareLayout {
[super prepareLayout];
// Need to enlarge visible rect slightly to avoid flickering.
CGRect visibleRect = CGRectInset((CGRect){.origin = self.collectionView.bounds.origin, .size = self.collectionView.frame.size}, -100, -100);
NSArray *itemsInVisibleRectArray = [super layoutAttributesForElementsInRect:visibleRect];
NSArray *cells = [itemsInVisibleRectArray filteredArrayUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(UICollectionViewLayoutAttributes *item, NSDictionary *bindings) {
return !item.representedElementKind;
}]];
NSSet *itemsIndexPathsInVisibleRectSet = [NSSet setWithArray:[cells valueForKey:@"indexPath"]];
// Remove any behaviours that are no longer visible.
NSArray *noLongerVisibleBehavioursCells = [self.dynamicAnimator.behaviors filteredArrayUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(UIAttachmentBehavior *behaviour, NSDictionary *bindings) {
UICollectionViewLayoutAttributes *item= (UICollectionViewLayoutAttributes*)[[behaviour items] firstObject];
if (!item.representedElementKind) {
BOOL currentlyVisible = [itemsIndexPathsInVisibleRectSet member:[item indexPath]] != nil;
return !currentlyVisible;
}
else {
return NO;
}
}]];
[noLongerVisibleBehavioursCells enumerateObjectsUsingBlock:^(UIAttachmentBehavior *behaviour, NSUInteger index, BOOL *stop) {
UICollectionViewLayoutAttributes *item = (UICollectionViewLayoutAttributes*)[[behaviour items] firstObject];
[self.dynamicAnimator removeBehavior:behaviour];
[self.visibleIndexPathsSet removeObject:[item indexPath]];
}];
// Add any newly visible behaviours.
CGPoint touchLocation = [self.collectionView.panGestureRecognizer locationInView:self.collectionView];
// A "newly visible" item is one that is in the itemsInVisibleRect(Set|Array) but not in the visibleIndexPathsSet
NSArray *newlyVisibleItems = [cells filteredArrayUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(UICollectionViewLayoutAttributes *item, NSDictionary *bindings) {
BOOL currentlyVisible = [self.visibleIndexPathsSet member:item.indexPath] != nil;
return !currentlyVisible;
}]];
[newlyVisibleItems enumerateObjectsUsingBlock:^(UICollectionViewLayoutAttributes *item, NSUInteger idx, BOOL *stop) {
CGPoint center = item.center;
UIAttachmentBehavior *springBehaviour = [[UIAttachmentBehavior alloc] initWithItem:item attachedToAnchor:center];
springBehaviour.length = 0.0f;
springBehaviour.damping = 0.8f;
springBehaviour.frequency = 1.0f;
// If our touchLocation is not (0,0), we'll need to adjust our item's center "in flight"
if (!CGPointEqualToPoint(CGPointZero, touchLocation)) {
CGFloat yDistanceFromTouch = fabs(touchLocation.y - springBehaviour.anchorPoint.y);
CGFloat xDistanceFromTouch = fabs(touchLocation.x - springBehaviour.anchorPoint.x);
CGFloat scrollResistance = (yDistanceFromTouch + xDistanceFromTouch) / 1500.0f;
if (self.latestDelta < 0) {
center.y += MAX(self.latestDelta, self.latestDelta*scrollResistance);
}
else {
center.y += MIN(self.latestDelta, self.latestDelta*scrollResistance);
}
item.center = center;
}
[self.dynamicAnimator addBehavior:springBehaviour];
[self.visibleIndexPathsSet addObject:item.indexPath];
}];
}
-(BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds {
UIScrollView *scrollView = self.collectionView;
CGFloat delta = newBounds.origin.y - scrollView.bounds.origin.y;
self.latestDelta = delta;
CGPoint touchLocation = [self.collectionView.panGestureRecognizer locationInView:self.collectionView];
__block UIDynamicAnimator *weakDynamicAnimator = self.dynamicAnimator;
[self.dynamicAnimator.behaviors enumerateObjectsUsingBlock:^(UIAttachmentBehavior *springBehaviour, NSUInteger idx, BOOL *stop) {
CGFloat yDistanceFromTouch = fabs(touchLocation.y - springBehaviour.anchorPoint.y);
CGFloat xDistanceFromTouch = fabs(touchLocation.x - springBehaviour.anchorPoint.x);
CGFloat scrollResistance = (yDistanceFromTouch + xDistanceFromTouch) / 1500.0f;
UICollectionViewLayoutAttributes *item = (UICollectionViewLayoutAttributes*)[springBehaviour.items firstObject];
CGPoint center = item.center;
if (delta < 0) {
center.y += MAX(delta, delta*scrollResistance);
}
else {
center.y += MIN(delta, delta*scrollResistance);
}
item.center = center;
[weakDynamicAnimator updateItemUsingCurrentState:item];
}];
return NO;
}
@end
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
let w = round(CellAspectRatio.width * collectionView.frame.width)
let h = round(CellAspectRatio.height * collectionView.frame.height)
return CGSizeMake(w, h)
}