UICollectionView标签选择器 iOS UICollectionView实现标签选择器
guojiezhi 人气:0近来,在项目中需要实现一个类似兴趣标签的选择器。由于标签的文字长度不定,所以标签的显示长度就不定。为了实现效果,就使用了UICollectionView来实现了每行的标签数量不定、cell的宽度自适应的效果。先在此分享出来:
1、自适应UICollectionViewCell
这里只是在自适应UICollectionViewCell上放一个和UICollectionViewCell保持一样大小的按钮,当选中和取消选中时改变按钮的文字颜色和边框颜色:
#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
2、UICollectionViewFlowLayout子类--YLWaterFlowLayout的实现
.h头文件
#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
.m文件
#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
实现思路:在YLWaterFlowLayout中使用originxArray和originyArray两个个数组记录了每一个自定义YLTagsCollectionViewCell的位置x和y。
在 -(UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath方法中通获得与当前YLTagsCollectionViewCell临近的“上一个YLTagsCollectionViewCell”的位置和尺寸信息,将上一个cell的x加上上一个cell的width来得到当前cell的x。同时还要判断当前cell的x+width是否会超越出屏幕右边缘,如果超出,则表明需要换行显示了,这时候就要修改y的值了。
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