1.实现思路
>第一种方案：UIScrollView 镶嵌三个UITableView (不推荐使用)
>第二种方案：UIScrollView 镶嵌UIImageView （需要解决循环利用的问题）
>第三种方案：UICollectionView
2.基本骨架Layout:需要重写的方法
）- (void)prepareLayout
）- (CGSize)collectionViewContentSize
）- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath
）- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect
.h
#import <UIKit/UIKit.h> @class JQWaterflowLayout; @protocol JQWaterflowLayoutDelegate <NSObject>
@required
- (CGFloat)waterflowLayout:(JQWaterflowLayout *)waterflowLayout heightForItemAtIndex:(NSUInteger)index itemWidth:(CGFloat)itemWidth; @optional
- (CGFloat)columnCountInWaterflowLayout:(JQWaterflowLayout *)waterflowLayout;
- (CGFloat)columnMarginInWaterflowLayout:(JQWaterflowLayout *)waterflowLayout;
- (CGFloat)rowMarginInWaterflowLayout:(JQWaterflowLayout *)waterflowLayout;
- (UIEdgeInsets)edgeInsetsInWaterflowLayout:(JQWaterflowLayout *)waterflowLayout;
@end @interface JQWaterflowLayout : UICollectionViewLayout
/** 代理 */
@property (nonatomic, weak) id<JQWaterflowLayoutDelegate> delegate;
@end
.m
#import "XMGWaterflowLayout.h" /** 默认的列数 */
static const NSInteger JQDefaultColumnCount = ;
/** 每一列之间的间距 */
static const CGFloat JQDefaultColumnMargin = ;
/** 每一行之间的间距 */
static const CGFloat JQDefaultRowMargin = ;
/** 边缘间距 */
static const UIEdgeInsets JQDefaultEdgeInsets = {, , , }; @interface JQWaterflowLayout()
/** 存放所有cell的布局属性 */
@property (nonatomic, strong) NSMutableArray *attrsArray;
/** 存放所有列的当前高度 */
@property (nonatomic, strong) NSMutableArray *columnHeights;
/** 内容的高度 */
@property (nonatomic, assign) CGFloat contentHeight; - (CGFloat)rowMargin;
- (CGFloat)columnMargin;
- (NSInteger)columnCount;
- (UIEdgeInsets)edgeInsets;
@end @implementation JQWaterflowLayout #pragma mark - 常见数据处理
- (CGFloat)rowMargin
{
if ([self.delegate respondsToSelector:@selector(rowMarginInWaterflowLayout:)]) {
return [self.delegate rowMarginInWaterflowLayout:self];
} else {
return JQDefaultRowMargin;
}
} - (CGFloat)columnMargin
{
if ([self.delegate respondsToSelector:@selector(columnMarginInWaterflowLayout:)]) {
return [self.delegate columnMarginInWaterflowLayout:self];
} else {
return JQDefaultColumnMargin;
}
} - (NSInteger)columnCount
{
if ([self.delegate respondsToSelector:@selector(columnCountInWaterflowLayout:)]) {
return [self.delegate columnCountInWaterflowLayout:self];
} else {
return JQDefaultColumnCount;
}
} - (UIEdgeInsets)edgeInsets
{
if ([self.delegate respondsToSelector:@selector(edgeInsetsInWaterflowLayout:)]) {
return [self.delegate edgeInsetsInWaterflowLayout:self];
} else {
return JQDefaultEdgeInsets;
}
} #pragma mark - 懒加载
- (NSMutableArray *)columnHeights
{
if (!_columnHeights) {
_columnHeights = [NSMutableArray array];
}
return _columnHeights;
} - (NSMutableArray *)attrsArray
{
if (!_attrsArray) {
_attrsArray = [NSMutableArray array];
}
return _attrsArray;
} /**
* 初始化
*/
- (void)prepareLayout
{
[super prepareLayout]; self.contentHeight = ; // 清除以前计算的所有高度
[self.columnHeights removeAllObjects];
for (NSInteger i = ; i < self.columnCount; i++) {
[self.columnHeights addObject:@(self.edgeInsets.top)];
} // 清除之前所有的布局属性
[self.attrsArray removeAllObjects];
// 开始创建每一个cell对应的布局属性
NSInteger count = [self.collectionView numberOfItemsInSection:];
for (NSInteger i = ; i < count; i++) {
// 创建位置
NSIndexPath *indexPath = [NSIndexPath indexPathForItem:i inSection:];
// 获取indexPath位置cell对应的布局属性
UICollectionViewLayoutAttributes *attrs = [self layoutAttributesForItemAtIndexPath:indexPath];
[self.attrsArray addObject:attrs];
}
} /**
* 决定cell的排布
*/
- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect
{
return self.attrsArray;
} /**
* 返回indexPath位置cell对应的布局属性
*/
- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath
{
// 创建布局属性
UICollectionViewLayoutAttributes *attrs = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath]; // collectionView的宽度
CGFloat collectionViewW = self.collectionView.frame.size.width; // 设置布局属性的frame
CGFloat w = (collectionViewW - self.edgeInsets.left - self.edgeInsets.right - (self.columnCount - ) * self.columnMargin) / self.columnCount;
CGFloat h = [self.delegate waterflowLayout:self heightForItemAtIndex:indexPath.item itemWidth:w]; // 找出高度最短的那一列
NSInteger destColumn = ;
CGFloat minColumnHeight = [self.columnHeights[] doubleValue];
for (NSInteger i = ; i < self.columnCount; i++) {
// 取得第i列的高度
CGFloat columnHeight = [self.columnHeights[i] doubleValue]; if (minColumnHeight > columnHeight) {
minColumnHeight = columnHeight;
destColumn = i;
}
} CGFloat x = self.edgeInsets.left + destColumn * (w + self.columnMargin);
CGFloat y = minColumnHeight;
if (y != self.edgeInsets.top) {
y += self.rowMargin;
}
attrs.frame = CGRectMake(x, y, w, h); // 更新最短那列的高度
self.columnHeights[destColumn] = @(CGRectGetMaxY(attrs.frame)); // 记录内容的高度
CGFloat columnHeight = [self.columnHeights[destColumn] doubleValue];
if (self.contentHeight < columnHeight) {
self.contentHeight = columnHeight;
}
return attrs;
} - (CGSize)collectionViewContentSize
{
// CGFloat maxColumnHeight = [self.columnHeights[0] doubleValue];
// for (NSInteger i = 1; i < self.columnCount; i++) {
// // 取得第i列的高度
// CGFloat columnHeight = [self.columnHeights[i] doubleValue];
//
// if (maxColumnHeight < columnHeight) {
// maxColumnHeight = columnHeight;
// }
// }
return CGSizeMake(, self.contentHeight + self.edgeInsets.bottom);
} @end