- 根据偏移量offset每次滚动特定的距离（类似pagingEnabled属性）
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IMG_8852.GIF
@interface N2_HomeWordsStudyHeaderView ()<UICollectionViewDelegateFlowLayout, UICollectionViewDelegate, UICollectionViewDataSource>
@property (nonatomic, strong) UICollectionView *collectionView;
@property (nonatomic, assign) CGFloat myOffsetX; // 滑动时的偏移量
@end
@implementation N2_HomeWordsStudyHeaderView
- (instancetype)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
self.backgroundColor = [UIColor whiteColor];
[self setupUI];
}
return self;
}
- (void)setupUI {
UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];
collectionView.delegate = self;
collectionView.dataSource = self;
collectionView.pagingEnabled = NO; /// 禁止分页滑动时，根据偏移量判断滑动到第几个item
collectionView.scrollEnabled = YES; /// 禁止滑动
collectionView.showsHorizontalScrollIndicator = NO;
[self addSubview:collectionView];
[collectionView makeConstraints:^(MASConstraintMaker *make) {
// make.left.mas_equalTo(self.mas_left).offset([UIScreen mainScreen].bounds.size.width/375*20);
// make.right.top.bottom.equalTo(self);
make.edges.equalTo(self);
}];
[collectionView registerClass:[N2_homeHeaderWordBookStudyCell class] forCellWithReuseIdentifier:NSStringFromClass([N2_homeHeaderWordBookStudyCell class])];
[collectionView registerClass:[N2_homeHeaderWordBookStudiedCell class] forCellWithReuseIdentifier:NSStringFromClass([N2_homeHeaderWordBookStudiedCell class])];
self.collectionView = collectionView;
self.collectionView.backgroundColor = [UIColor whiteColor];
// [self addLeftAndRightTouchGesture];
}
- (void)refreshHomeNewWordStudyCollectionView {
[self.collectionView reloadData];
}
#pragma mark -- <UICollectionViewDelegate, UICollectionViewDataSource>
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return 1;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return self.planDetailModelLists.count;
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
// item 大小
return CGSizeMake([UIScreen mainScreen].bounds.size.width/375*335, [UIScreen mainScreen].bounds.size.width/375*525);
}
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section {
// 行间距（上下）
// return 40;
return [UIScreen mainScreen].bounds.size.width/375*10;
}
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section {
// 列间距（左右）
return [UIScreen mainScreen].bounds.size.width/375*1;
}
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
return UIEdgeInsetsMake([UIScreen mainScreen].bounds.size.width/375*5, [UIScreen mainScreen].bounds.size.width/375*20, [UIScreen mainScreen].bounds.size.width/375*5, [UIScreen mainScreen].bounds.size.width/375*20);
}
- (__kindof UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
N2_homeHeaderWordBookStudiedCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:NSStringFromClass([N2_homeHeaderWordBookStudiedCell class]) forIndexPath:indexPath];
if (self.planDetailModelLists.count > 0) {
cell.planDetailModel = self.planDetailModelLists[indexPath.row];
}
return cell;
}
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
N2_homeHeaderWordBookStudiedCell *cell = (N2_homeHeaderWordBookStudiedCell *)[collectionView cellForItemAtIndexPath:indexPath];
}
#pragma mark -- -- 以下四个方法，就是实现UICollectionView根据偏移量offset滑动，实现（pagingEnabled）效果的方法
/*
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
NSLog(@"开始滑动 scrollView.contentOffset.x = %.2f ", scrollView.contentOffset.x);
// 整个引导页先弄一个UIViewController，在VC中添加其他需要的东西，比如一个UICollectionView、“跳过”按钮，和翻页控件UIpageControl
// 可以设置刚开始进入APP时的引导图，可以使用UICollectionView，再在上面添加“跳过”按钮
// 原理：当scrollView.contentOffset.x < 0时，禁止向右滑动，同理，滑到最后一个item，也设置禁止在向左滑动
if (scrollView.contentOffset.x < 0) {
self.collectionView.scrollEnabled = NO;
} else {
self.collectionView.scrollEnabled = YES;
}
}
**/
- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView {
// 停止滑动时，当前的偏移量（即最近停止的位置）
self.myOffsetX = scrollView.contentOffset.x;
NSLog(@"scrollView.contentOffset.x = %.2f", self.myOffsetX);
}
/// collectionView.pagingEnabled = NO; /// 禁止分页滑动时，根据偏移量判断滑动到第几个item
/// 滑动 “减速滚动时” 是触发的代理，当用户用力滑动或者清扫时触发
- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView {
// 为了简化代码用了一个手势从滑动方向判断，所以用到了绝对值比对判断 左右滑动的值。
// fabs ：处理double类型的取绝对值
if (fabs(scrollView.contentOffset.x - self.myOffsetX) > 10) {
[self scrollToNextPageOrLastPage:scrollView];
}
}
/// 用户拖拽时 调用
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset{
if (fabs(scrollView.contentOffset.x - self.myOffsetX) > 10) {
[self scrollToNextPageOrLastPage:scrollView];
}
}
- (void)scrollToNextPageOrLastPage:(UIScrollView *)scrollView {
/// 之前停止的位置，判断左滑、右滑
if (scrollView.contentOffset.x > self.myOffsetX) { // i > 0（左滑，下一个（i最大为cell个数））
// 计算移动的item的个数（item.width + 间距）
NSInteger i = scrollView.contentOffset.x/[UIScreen mainScreen].bounds.size.width/375*(335+10)+1;
NSIndexPath *index = [NSIndexPath indexPathForRow:i inSection:0];
// item居中显示
[self.collectionView scrollToItemAtIndexPath:index atScrollPosition:UICollectionViewScrollPositionCenteredHorizontally animated:YES];
NSLog(@"😆index = %ld", i);
}else{ // i <= 0 （右滑，上一个）（i 最小为-1，所以有需要的话，在这里添加判断，使其最小为 i = 0）
NSInteger i = scrollView.contentOffset.x/[UIScreen mainScreen].bounds.size.width/375*(335+10)+1;
NSIndexPath *index = [NSIndexPath indexPathForRow:i-1 inSection:0];
[self.collectionView scrollToItemAtIndexPath:index atScrollPosition:UICollectionViewScrollPositionCenteredHorizontally animated:YES];
NSLog(@"☺️☺️☺️index = %ld", i-1);
}
}
@end
