iOS UICollectionView实现标签选择器

#pragma mark---标签cell@implementation YLTagsCollectionViewCell-(instancetype)initWithFrame:(CGRect)frame{ if(self = [super initWithFrame:frame]){  self.backgroundColor = [UIColor clearColor];  _btn = [UIButton buttonWithType:UIButtonTypeCustom];  //此处可以根据需要自己使用自动布局代码实现  _btn.frame = CGRectMake(0, 0, frame.size.width, frame.size.height);  _btn.backgroundColor = [UIColor whiteColor];  _btn.titleLabel.font = [UIFont systemFontOfSize:14];  _btn.layer.borderWidth = 1.f;  _btn.layer.cornerRadius = frame.size.height/2.0;  _btn.layer.masksToBounds = YES;  [_btn setTitleColor:HEXCOLOR(0x666666) forState:UIControlStateNormal];  _btn.layer.borderColor = HEXCOLOR(0xdddddd).CGColor;  _btn.userInteractionEnabled = NO;  [self.contentView addSubview:_btn]; } return self;} -(void)layoutSubviews{ [super layoutSubviews]; _btn.frame = CGRectMake(0, 0, self.contentView.frame.size.width, self.contentView.frame.size.height);} -(void)setSelected:(BOOL)selected{ [super setSelected:selected]; _btn.layer.borderColor = selected?HEXCOLOR(0xffb400).CGColor:HEXCOLOR(0xdddddd).CGColor; [_btn setTitleColor:selected?HEXCOLOR(0xffb400):HEXCOLOR(0x666666) forState:UIControlStateNormal];} -(void)setHighlighted:(BOOL)highlighted{ [super setHighlighted:highlighted]; _btn.layer.borderColor = highlighted?HEXCOLOR(0xffb400).CGColor:HEXCOLOR(0xdddddd).CGColor; [_btn setTitleColor:highlighted?HEXCOLOR(0xffb400):HEXCOLOR(0x666666) forState:UIControlStateNormal];} @end

#import <UIKit/UIKit.h> @class YLWaterFlowLayout;@protocol YLWaterFlowLayoutDelegate <NSObject>/**通过代理获得每个cell的宽度*/- (CGFloat)waterFlowLayout:(YLWaterFlowLayout *)layout widthAtIndexPath:(NSIndexPath *)indexPath; @end @interface YLWaterFlowLayout : UICollectionViewFlowLayout@property (nonatomic,assign) id<YLWaterFlowLayoutDelegate> delegate;@property(nonatomic,assign)CGFloat rowHeight;///< 固定行高 @end

#import "YLWaterFlowLayout.h" @interface YLWaterFlowLayout()@property(nonatomic,strong)NSMutableArray *originxArray;@property(nonatomic,strong)NSMutableArray *originyArray;@end @implementation YLWaterFlowLayout#pragma mark - 初始化属性- (instancetype)init { self = [super init]; if (self) {  self.minimumInteritemSpacing = 5;//同一行不同cell间距  self.minimumLineSpacing = 5;//行间距  self.sectionInset = UIEdgeInsetsMake(10, 10, 10, 10);  self.scrollDirection = UICollectionViewScrollDirectionVertical;  _originxArray = [NSMutableArray array];  _originyArray = [NSMutableArray array]; } return self;} #pragma mark - 重写父类的方法，实现瀑布流布局#pragma mark - 当尺寸有所变化时，重新刷新- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds { return YES;} - (void)prepareLayout { [super prepareLayout];} #pragma mark - 处理所有的Item的layoutAttributes- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect{ NSArray *array = [super layoutAttributesForElementsInRect:rect]; NSMutableArray *mutArray = [NSMutableArray arrayWithCapacity:array.count]; for(UICollectionViewLayoutAttributes *attrs in array){  UICollectionViewLayoutAttributes *theAttrs = [self layoutAttributesForItemAtIndexPath:attrs.indexPath];  [mutArray addObject:theAttrs]; } return mutArray;} #pragma mark - 处理单个的Item的layoutAttributes- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath{ CGFloat x = self.sectionInset.left; CGFloat y = self.sectionInset.top; //判断获得前一个cell的x和y NSInteger preRow = indexPath.row - 1; if(preRow >= 0){  if(_originyArray.count > preRow){   x = [_originxArray[preRow]floatValue];   y = [_originyArray[preRow]floatValue];  }  NSIndexPath *preIndexPath = [NSIndexPath indexPathForItem:preRow inSection:indexPath.section];  CGFloat preWidth = [self.delegate waterFlowLayout:self widthAtIndexPath:preIndexPath];  x += preWidth + self.minimumInteritemSpacing; }  CGFloat currentWidth = [self.delegate waterFlowLayout:self widthAtIndexPath:indexPath]; //保证一个cell不超过最大宽度 currentWidth = MIN(currentWidth, self.collectionView.frame.size.width - self.sectionInset.left - self.sectionInset.right); if(x + currentWidth > self.collectionView.frame.size.width - self.sectionInset.right){  //超出范围，换行  x = self.sectionInset.left;  y += _rowHeight + self.minimumLineSpacing; } // 创建属性 UICollectionViewLayoutAttributes *attrs = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath]; attrs.frame = CGRectMake(x, y, currentWidth, _rowHeight); _originxArray[indexPath.row] = @(x); _originyArray[indexPath.row] = @(y); return attrs;} #pragma mark - CollectionView的滚动范围- (CGSize)collectionViewContentSize{ CGFloat width = self.collectionView.frame.size.width;  __block CGFloat maxY = 0; [_originyArray enumerateObjectsUsingBlock:^(NSNumber *number, NSUInteger idx, BOOL * _Nonnull stop) {  if ([number floatValue] > maxY) {   maxY = [number floatValue];  } }];  return CGSizeMake(width, maxY + _rowHeight + self.sectionInset.bottom);} @end