# LBMiddleExpandLayout

**Repository Path**: romancao/lbmiddle-expand-layout

## Basic Information

- **Project Name**: LBMiddleExpandLayout
- **Description**: 一个iOS中间放大自定义layout
- **Primary Language**: Unknown
- **License**: MIT
- **Default Branch**: main
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 1
- **Created**: 2024-10-25
- **Last Updated**: 2024-10-25

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# LiuboMiddleExpandLayout

[![CI Status](https://img.shields.io/travis/liubo/LiuboMiddleExpandLayout.svg?style=flat)](https://travis-ci.org/liubo/LiuboMiddleExpandLayout)
[![Version](https://img.shields.io/cocoapods/v/LiuboMiddleExpandLayout.svg?style=flat)](https://cocoapods.org/pods/LiuboMiddleExpandLayout)
[![License](https://img.shields.io/cocoapods/l/LiuboMiddleExpandLayout.svg?style=flat)](https://cocoapods.org/pods/LiuboMiddleExpandLayout)
[![Platform](https://img.shields.io/cocoapods/p/LiuboMiddleExpandLayout.svg?style=flat)](https://cocoapods.org/pods/LiuboMiddleExpandLayout)

## Example

To run the example project, clone the repo, and run `pod install` from the Example directory first.

## Requirements

## Installation

LiuboMiddleExpandLayout is available through [CocoaPods](https://cocoapods.org). To install
it, simply add the following line to your Podfile:

```ruby
pod 'LiuboMiddleExpandLayout'

- (UICollectionView *)collectionView
{
    if (!_collectionView) {
        LBMiddleExpandLayout *layout = [[LBMiddleExpandLayout alloc] init];
        layout.itemSize = CGSizeMake(284 * PLUS_SCALE, 582*PLUS_SCALE);
        layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
        layout.minimumLineSpacing = 28*PLUS_SCALE;
        layout.minimumInteritemSpacing = 28*PLUS_SCALE;
        _collectionView = [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];
        _collectionView.delegate = self;
        _collectionView.dataSource = self;
        _collectionView.pagingEnabled = NO;
        _collectionView.showsHorizontalScrollIndicator = NO;
        _collectionView.backgroundColor = [UIColor clearColor];
        [_collectionView registerClass:[LBCollectionViewCell class] forCellWithReuseIdentifier:NSStringFromClass([LBCollectionViewCell class])];
        [_collectionView setFrame:CGRectMake(0,  9 * PLUS_SCALE, SCREEN_WIDTH,SCREEN_HEIGHT  - 9 * PLUS_SCALE - 90 * PLUS_SCALE)];
    }
    return _collectionView;
}

//手指拖动开始
-(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
    self.m_dragStartX = scrollView.contentOffset.x;
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    if (self.endDraggingOffset < 0 && scrollView.contentOffset.x >= self.endDraggingOffset) {
        //这里是为了上刷新的时候，停留在固定的偏移量，展示loading
        scrollView.contentOffset = CGPointMake(self.endDraggingOffset, 0);
    }
    
    if (!self.hasNextPage) {
        return;
    }
    
    /*
     遇到一次精度问题，正在刷新的时候 应该展示loading，但是由于精度问题，这时候
      scrollView.contentOffset.x = -52.333333 ， refreshThreshold = -52.399998，
     如果 是 (scrollView.contentOffset.x <= refreshThreshold )，就会造成loading隐藏，
     所以这里+0.5
     
     */
    if (scrollView.contentOffset.x <= (refreshThreshold + 0.5)) {
        self.refreshView.hidden = NO;
    } else {
        self.refreshView.hidden = YES;
    }
}

//手指拖动停止
-(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
    self.m_dragEndX = scrollView.contentOffset.x;
    dispatch_async(dispatch_get_main_queue(), ^{
        [self fixCellToCenter];
    });
    if (scrollView.contentOffset.x < refreshThreshold) {
        if (!self.hasNextPage) {
            return;
        }
        if (self.isLoadingMore) {
            return;
        }
        self.endDraggingOffset = refreshThreshold;
        NSMutableArray *array = [NSMutableArray array];
        for (int i = (self.signsArray.count + 10); i > self.signsArray.count; i --) {
            [array addObject:[NSString stringWithFormat:@"%d", i]];
        }
        [self refreshHandleWithArray:array];
        self.isLoadingMore = YES;
    }
}

#pragma mark - private

- (void)fixCellToCenter {
    //最小滚动距离
    float dragMiniDistance = self.view.bounds.size.width/20.0f;
    if (self.m_dragStartX -  self.m_dragEndX >= dragMiniDistance) {
        self.m_currentIndex -= 1;//向右
    } else if(self.m_dragEndX -  self.m_dragStartX >= dragMiniDistance){
        self.m_currentIndex += 1;//向左
    }
    NSInteger maxIndex = [_collectionView numberOfItemsInSection:0] - 1;
    self.m_currentIndex = self.m_currentIndex <= 0 ? 0 : self.m_currentIndex;
    self.m_currentIndex = self.m_currentIndex >= maxIndex ? maxIndex : self.m_currentIndex;
    [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForRow:self.m_currentIndex inSection:0] atScrollPosition:UICollectionViewScrollPositionCenteredHorizontally animated:YES];
}

```

## Demonstrate

![Image text](https://gitee.com/liuboliu/lbmiddle-expand-layout/raw/main/2023-07-08%2019.52.38.gif)
![Image text](https://gitee.com/liuboliu/lbmiddle-expand-layout/raw/main/2024-06-02%2018.26.56.gif)


## Author

liubo, liubo@thepaper.cn

## License

LiuboMiddleExpandLayout is available under the MIT license. See the LICENSE file for more info.