UICollectionViewTransitionLayout 是iOS 7 的新特性
作用：一種特殊類型的布局對(duì)象 桅打，用來進(jìn)行兩個(gè)集合視(UICollectionView)之間的平滑切換胡岔。和UIViewControllerInteractiveTransitioning聯(lián)合使用仗嗦，能夠?qū)崿F(xiàn)很棒的交互體驗(yàn)。
NS_CLASS_AVAILABLE_IOS(7_0) @interface UICollectionViewTransitionLayout : UICollectionViewLayout
// 過度完成的百分比
@property (assign, nonatomic) CGFloat transitionProgress;
// 當(dāng)前布局對(duì)象
@property (readonly, nonatomic) UICollectionViewLayout *currentLayout;
// 新布局對(duì)象
@property (readonly, nonatomic) UICollectionViewLayout *nextLayout;
// 初始化并返回一個(gè)轉(zhuǎn)換布局對(duì)象
- (instancetype)initWithCurrentLayout:(UICollectionViewLayout *)currentLayout nextLayout:(UICollectionViewLayout *)newLayout NS_DESIGNATED_INITIALIZER;
- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder NS_DESIGNATED_INITIALIZER;
- (instancetype)init NS_UNAVAILABLE;
- (void)updateValue:(CGFloat)value forAnimatedKey:(NSString *)key;
// 指定鍵最近設(shè)置的值
- (CGFloat)valueForAnimatedKey:(NSString *)key;
@end
