iPhone.gif
- 不同组之间可以设置不同的布局属性
- 每组可添加头部/尾部视图
- 通过delegate计算出头部/尾部/item frame
- 从写父类
UICollectionViewLayout方法
自定义HJCollectionViewWaterfallLayout
#import <UIKit/UIKit.h>
static NSString *const HJElementKindSectionHeader = @"HJElementKindSectionHeader";
static NSString *const HJElementKindSectionFooter = @"HJElementKindSectionFooter";
@class HJCollectionViewWaterfallLayout;
@protocol HJCollectionViewWaterfallLayoutDelegate <UICollectionViewDelegate>
@required
/**
item size
*/
- (CGSize)hj_collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath;
@optional
/**
每组单行的排布个数
*/
- (NSInteger)hj_collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout columCountAtSection:(NSInteger)section;
/**
每组头部视图的高度
*/
- (CGFloat)hj_collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout heightForHeaderAtSection:(NSInteger)section;
/**
每组尾部视图的高度
*/
- (CGFloat)hj_collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout heightForFooterAtSection:(NSInteger)section;
/**
每组的UIEdgeInsets
*/
- (UIEdgeInsets)hj_collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSection:(NSInteger)section;
/**
每组的minimumLineSpacing 行与行之间的距离
*/
- (CGFloat)hj_collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSection:(NSInteger)section;
/**
每组的minimumInteritemSpacing 同一行item之间的距离
*/
- (CGFloat)hj_collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSection:(NSInteger)section;
@end
@interface HJCollectionViewWaterfallLayout : UICollectionViewLayout
@property (nonatomic, weak) id<HJCollectionViewWaterfallLayoutDelegate>delegate;
@property (nonatomic, assign) NSInteger columCount; // 每行多少个item 默认为 1
@property (nonatomic, assign) CGFloat minimumLineSpacing; // 行于行之间的距离 默认 10.0
@property (nonatomic, assign) CGFloat minimumInteritemSpacing; // 同一行item之间的距离 默认 10.0
@property (nonatomic, assign) CGFloat sectionHeaderH; // 组头部视图的高度
@property (nonatomic, assign) CGFloat sectionFooterH; // 组尾部视图的高度
@end
需重写的父类方法
- (void)prepareLayout;
- (CGSize)collectionViewContentSize ;
- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)path ;
- (UICollectionViewLayoutAttributes *)layoutAttributesForSupplementaryViewOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath;
- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect;
- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds;
