iOS 联动

连动.gif

实现思路##

在做一个页面之前,一定要先思考好应该如何写,方法用对了是可以省很多事的.对于这样的一个连动的页面.我采取的方法是使用两个UICollectionView和若干个UITableView.顶部头是一个UICollectionView,下面滚动页是一个UICollectionView,滚动页里面的每一个cell都包含一个UITableView.滚动的横条用的是CALayer,因为CALayer改变位置后自带隐式动画,可以省去写动画的代码.

头部视图WYTradeHeaderView.h

/// 滚动到了第几页
- (void)slideToIndex:(NSInteger)index;
/// 滚动到几点几
- (void)slideToRatio:(CGFloat)ratio;

头部视图WYTradeHeaderView.m其中的CELL_WIDTH代表的是头部cell的宽度,具体在项目中由自己设置.

#pragma mark - private
- (void)slideToIndex:(NSInteger)index {
    CGRect slideRect = _slideLayer.frame;
    slideRect.origin.x = index * CELL_WIDTH;
    _slideLayer.frame = slideRect;
    
    self.selectedCell = (WLTradeHeadCell *)[_collectionView cellForItemAtIndexPath:[NSIndexPath indexPathForRow:index inSection:0]];
}

- (void)slideToRatio:(CGFloat)ratio {
    CGRect slideRect = _slideLayer.frame;
    slideRect.origin.x = ratio * CELL_WIDTH;
    [CATransaction begin];
    [CATransaction setDisableActions:YES];
    _slideLayer.frame = slideRect;
    [CATransaction commit];
    
    self.selectedCell = (WLTradeHeadCell *)[_collectionView cellForItemAtIndexPath:[NSIndexPath indexPathForRow:ratio + 0.5 inSection:0]];
}

#pragma mark - setter
- (void)setSelectedCell:(WLTradeHeadCell *)selectedCell {
    _selectedCell.nameLabel.textColor = WLColorLightGray_text;
    selectedCell.nameLabel.textColor = WLColorBlue;
    
    _selectedCell = selectedCell;
}

底部UICollectionView的主要操作,监听底部视图的滚动,然后实时更改头部视图,让其实现联动

- (void)viewDidLoad {
    [super viewDidLoad];

    [self prepareHeaderView];
}

- (void)prepareHeaderView {
    __weak typeof(_collectionView) weakCollectionView = _collectionView;
    _headView = [WLTradeHeadView tradeHeadViewWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, 45) onClick:^(NSInteger index) {
        [weakCollectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:index inSection:0] atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];
    }];
}
#pragma mark - UIScrollViewDelegate
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    [_headView slideToRatio:scrollView.contentOffset.x / SCREEN_WIDTH];
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
    self.currentPage = scrollView.contentOffset.x / SCREEN_WIDTH;
}

#pragma mark - setter
- (void)setCurrentPage:(NSInteger)currentPage {
    _currentPage = currentPage;
    
    [_headView slideToIndex:currentPage];
}