Swift
import UIKit
protocol SPWaterflowLayoutDelegate: NSObjectProtocol {
func waterflowLayout(view: SPWaterflowLayout, heightForItemAtIndex: Int, itemWidth: CGFloat) -> CGFloat
func columnCount(in view: SPWaterflowLayout) -> NSInteger
func columnMargin(in view: SPWaterflowLayout) -> CGFloat
func rowMargin(in view: SPWaterflowLayout) -> CGFloat
func edgeInsets(in view: SPWaterflowLayout) -> UIEdgeInsets
}
extension SPWaterflowLayoutDelegate {
func columnCount(in view: SPWaterflowLayout) -> NSInteger { return 2 }
func columnMargin(in view: SPWaterflowLayout) -> CGFloat { return 10 }
func rowMargin(in view: SPWaterflowLayout) -> CGFloat { return 10 }
func edgeInsets(in view: SPWaterflowLayout) -> UIEdgeInsets { return UIEdgeInsets(top: 10, left: 10, bottom: 10, right: 10) }
}
class SPWaterflowLayout: UICollectionViewLayout {
weak var delegate: SPWaterflowLayoutDelegate?
private var attrsArray = [UICollectionViewLayoutAttributes]()
private var columnHeights = [CGFloat]()
private var contentHeight: CGFloat = 0
private var columnCount: NSInteger {
get {
if let count = delegate?.columnCount(in: self) {
return count
}
return 2
}
}
private var columnMargin: CGFloat {
get {
if let margin = delegate?.columnMargin(in: self) {
return margin
}
return 3
}
}
private var rowMargin: CGFloat {
get {
if let margin = delegate?.columnMargin(in: self) {
return margin
}
return 3
}
}
private var edgeInsets: UIEdgeInsets {
get {
if let edge = delegate?.edgeInsets(in: self) {
return edge
}
return UIEdgeInsets(top: 3, left: 3, bottom: 3, right: 3)
}
}
}
extension SPWaterflowLayout {
override func prepare() {
super.prepare()
contentHeight = 0
columnHeights.removeAll()
for _ in 0..<columnCount {
columnHeights.append(edgeInsets.top)
}
attrsArray.removeAll()
guard let count = collectionView?.numberOfItems(inSection: 0) else {
return
}
for i in 0..<count {
if let attrs = layoutAttributesForItem(at: IndexPath(item: i, section: 0)) {
attrsArray.append(attrs)
}
}
}
override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
return attrsArray
}
override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
let attrs = UICollectionViewLayoutAttributes(forCellWith: indexPath)
guard let collectionViewWidth = collectionView?.frame.width else {
return attrs
}
let width = (collectionViewWidth - edgeInsets.left - edgeInsets.right - (CGFloat(columnCount) - 1) * columnMargin) / CGFloat(columnCount)
guard let height = delegate?.waterflowLayout(view: self, heightForItemAtIndex: indexPath.item, itemWidth: width) else {
return attrs
}
var destColumn: NSInteger = 0
var minColumnHeight: CGFloat = columnHeights[0]
for i in 0..<columnCount {
let columnHeight = columnHeights[i]
if minColumnHeight > columnHeight {
minColumnHeight = columnHeight
destColumn = i
}
}
let x = edgeInsets.left + CGFloat(destColumn) * (width + columnMargin)
var y = minColumnHeight
if y != edgeInsets.top {
y += rowMargin
}
attrs.frame = CGRect(x: x, y: y, width: width, height: height)
columnHeights[destColumn] = attrs.frame.maxY
let columnHeight = columnHeights[destColumn]
if contentHeight < columnHeight {
contentHeight = columnHeight
}
return attrs
}
override var collectionViewContentSize: CGSize {
return CGSize(width: 0, height: contentHeight + edgeInsets.bottom)
}
}
OC
#import <UIKit/UIKit.h>
@class SPWaterflowLayout;
@protocol SPWaterflowLayoutDelegate <NSObject>
@required
/// 高度
- (CGFloat)waterflowLayout:(SPWaterflowLayout *)waterflowLayout heightForItemAtIndex:(NSUInteger)index itemWidth:(CGFloat)itemWidth;
@optional
/// 竖排 数
- (CGFloat)columnCountInWaterflowLayout:(SPWaterflowLayout *)waterflowLayout;
/// 竖向 间距
- (CGFloat)columnMarginInWaterflowLayout:(SPWaterflowLayout *)waterflowLayout;
/// 横向 间距
- (CGFloat)rowMarginInWaterflowLayout:(SPWaterflowLayout *)waterflowLayout;
/// 边缘间距
- (UIEdgeInsets)edgeInsetsInWaterflowLayout:(SPWaterflowLayout *)waterflowLayout;
@end
@interface SPWaterflowLayout : UICollectionViewLayout
@property (nonatomic, weak) id<SPWaterflowLayoutDelegate> delegate;
@end
#import "SPWaterflowLayout.h"
/// 默认的列数
static const NSInteger SPDefaultColumnCount = 3;
/// 每一列之间的间距
static const CGFloat SPDefaultColumnMargin = 10;
/// 每一行之间的间距
static const CGFloat SPDefaultRowMargin = 10;
/// 边缘间距
static const UIEdgeInsets SPDefaultEdgeInsets = {10, 10, 10, 10};
@interface SPWaterflowLayout()
/// 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 SPWaterflowLayout
- (CGFloat)rowMargin {
if ([self.delegate respondsToSelector:@selector(rowMarginInWaterflowLayout:)]) {
return [self.delegate rowMarginInWaterflowLayout:self];
} else {
return SPDefaultRowMargin;
}
}
- (CGFloat)columnMargin {
if ([self.delegate respondsToSelector:@selector(columnMarginInWaterflowLayout:)]) {
return [self.delegate columnMarginInWaterflowLayout:self];
} else {
return SPDefaultColumnMargin;
}
}
- (NSInteger)columnCount {
if ([self.delegate respondsToSelector:@selector(columnCountInWaterflowLayout:)]) {
return [self.delegate columnCountInWaterflowLayout:self];
} else {
return SPDefaultColumnCount;
}
}
- (UIEdgeInsets)edgeInsets {
if ([self.delegate respondsToSelector:@selector(edgeInsetsInWaterflowLayout:)]) {
return [self.delegate edgeInsetsInWaterflowLayout:self];
} else {
return SPDefaultEdgeInsets;
}
}
- (void)prepareLayout {
[super prepareLayout];
self.contentHeight = 0;
// 清除以前计算的所有高度
[self.columnHeights removeAllObjects];
for (NSInteger i = 0; 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:0];
for (NSInteger i = 0; i < count; i++) {
// 创建位置
NSIndexPath *indexPath = [NSIndexPath indexPathForItem:i inSection:0];
// 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 - 1) * 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 = 0;
CGFloat minColumnHeight = [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 (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 {
return CGSizeMake(0, self.contentHeight + self.edgeInsets.bottom);
}
- (NSMutableArray *)columnHeights {
if (!_columnHeights) {
_columnHeights = [NSMutableArray array];
}
return _columnHeights;
}
- (NSMutableArray *)attrsArray {
if (!_attrsArray) {
_attrsArray = [NSMutableArray array];
}
return _attrsArray;
}
@end
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