开源一个仿时光网选票组件

一、项目简介

该项目利用UIScrollView的各种滚动事件的监听，仿造时光网选择电影票的UI而开发的一个自定义View。使用简单，可扩展性很强。具备点击每个Item进行选票功能，选票居中功能，滑动时自动选择距离中间最近的View处于选中状态，而且对于滑动时松开手的时候是否有初始速度进行了区分处理。
案例演示如下：

仿时光网选票UI

二、项目讲解

1、初始化UIScrollView中每个Item的View，把每个View放到_viewArray数组中，方便接下来的定位和管理。每一个View中包含一个UIImageView，把每一个UIImageView放在_imageViewArray数组中，方便接下来的进行随着滑动的放大和缩小操作。

-(instancetype)initViewWithImageArray:(NSArray *)imageArray{
    if (!imageArray) {
        return nil;
    }
    if (imageArray.count<1) {
        return nil;
    }
    
    NSInteger totalNum = imageArray.count;
    self = [super initWithFrame:CGRectMake(0, 40, SCREEN_WIDTH, 120)];
    if (self) {
        _scrollview = [[UIScrollView alloc] initWithFrame:self.bounds];
        _scrollview.contentSize = CGSizeMake(LEFT_SPACE*2+SELECT_VIEW_WIDTH+(totalNum-1)*NORMAL_VIEW_WIDTH+(totalNum-1)*ITEM_SPACE, 120);
        _scrollview.delegate = self;
        _scrollview.showsHorizontalScrollIndicator = NO;
        _scrollview.decelerationRate = UIScrollViewDecelerationRateFast;
        [self addSubview:_scrollview];
        
        UIView *backView = [[UIView alloc] initWithFrame:CGRectMake(-SCREEN_WIDTH, 0, _scrollview.contentSize.width+SCREEN_WIDTH*2, _scrollview.contentSize.height-20)];
        backView.backgroundColor = [UIColor lightGrayColor];
        [_scrollview addSubview:backView];
        
        _imageViewArray = [NSMutableArray array];
        _viewArray = [NSMutableArray array];
        
        CGFloat offsetX = LEFT_SPACE;
        for (int i=0; i

2、在滑动的过程中，我们实时的需要改变计算哪一个Item距离中间最近，在过渡到最中间的过程中，选中的Item距离中间越近，选中Item的frame越大，反则越小。并且对于边界值进行判断。

-(void)scrollViewDidScroll:(UIScrollView *)scrollView{
    int currentIndex = scrollView.contentOffset.x/(NORMAL_VIEW_WIDTH+ITEM_SPACE);
    if (currentIndex>_imageViewArray.count-2||currentIndex<0) {
        return;
    }
    int rightIndex = currentIndex+1;
    UIImageView *currentImageView = _imageViewArray[currentIndex];
    UIImageView *rightImageView = _imageViewArray[rightIndex];
    
    
    CGFloat scale =  (scrollView.contentOffset.x-currentIndex*(NORMAL_VIEW_WIDTH+ITEM_SPACE))/(NORMAL_VIEW_WIDTH+ITEM_SPACE);
    
    //NSLog(@"%f",scale);
    
    CGFloat width = SELECT_VIEW_WIDTH-scale*(SELECT_VIEW_WIDTH-NORMAL_VIEW_WIDTH);
    CGFloat height = SELECT_VIEW_HEIGHT-scale*(SELECT_VIEW_HEIGHT-NORMAL_VIEW_HEIGHT);
    if (widthSELECT_VIEW_WIDTH) {
        width = SELECT_VIEW_WIDTH;
    }
    if (height>SELECT_VIEW_HEIGHT) {
        height = SELECT_VIEW_HEIGHT;
    }
    CGRect rect = CGRectMake(-(width-NORMAL_VIEW_WIDTH)/2, 0, width, height);
    currentImageView.frame = rect;
    
    width = NORMAL_VIEW_WIDTH+scale*(SELECT_VIEW_WIDTH-NORMAL_VIEW_WIDTH);
    height = NORMAL_VIEW_HEIGHT+scale*(SELECT_VIEW_HEIGHT-NORMAL_VIEW_HEIGHT);
    if (widthSELECT_VIEW_WIDTH) {
        width = SELECT_VIEW_WIDTH;
    }
    if (height>SELECT_VIEW_HEIGHT) {
        height = SELECT_VIEW_HEIGHT;
    }
    rect = CGRectMake(-(width-NORMAL_VIEW_WIDTH)/2, 0, width, height);
    NSLog(@"%@",NSStringFromCGRect(rect));
    rightImageView.frame = rect;
}

3、点击某一个Item，让Item处于中间选中状态。

-(void)clickImage:(UITapGestureRecognizer *)tap{
    UIImageView *imageView = (UIImageView *)tap.view;
    NSInteger tag = imageView.tag;
    
    UIView *containerView = _viewArray[tag];
    
    CGFloat offsetX = CGRectGetMidX(containerView.frame)-SCREEN_WIDTH/2;
    
    
    [_scrollview scrollRectToVisible:CGRectMake(offsetX, 0, SCREEN_WIDTH, 120) animated:YES];
    
    if (_delegate && [_delegate respondsToSelector:@selector(itemSelected:)]) {
        [_delegate itemSelected:tag];
    }
    
}

4、当用户在滑动结束，并具有初始速度的时候，当滑动停止的时候，我们需要把距离中间最近Item定位到最中间。

-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
    int currentIndex = roundf(scrollView.contentOffset.x/(NORMAL_VIEW_WIDTH+ITEM_SPACE));
    UIView *containerView = _viewArray[currentIndex];
    CGFloat offsetX = CGRectGetMidX(containerView.frame)-SCREEN_WIDTH/2;
    [_scrollview scrollRectToVisible:CGRectMake(offsetX, 0, SCREEN_WIDTH, 120) animated:YES];
    if (_delegate && [_delegate respondsToSelector:@selector(itemSelected:)]) {
        [_delegate itemSelected:currentIndex];
    }
}

5、当用户在滑动结束的时候，但是没有初始速度的时候，此时不会触发-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView方法，我们需要在-(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate方法中，进行处理。

-(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
    if (!decelerate) {
        int currentIndex = roundf(scrollView.contentOffset.x/(NORMAL_VIEW_WIDTH+ITEM_SPACE));
        UIView *containerView = _viewArray[currentIndex];
        CGFloat offsetX = CGRectGetMidX(containerView.frame)-SCREEN_WIDTH/2;
        [_scrollview scrollRectToVisible:CGRectMake(offsetX, 0, SCREEN_WIDTH, 120) animated:YES];
        if (_delegate && [_delegate respondsToSelector:@selector(itemSelected:)]) {
            [_delegate itemSelected:currentIndex];
        }
    }
}

6、注意点，设置
_scrollview.decelerationRate = UIScrollViewDecelerationRateFast;
减慢UIScrollView滑动速度。会使用户体验更好。

3、项目使用

1、本项目支持CocosPod，引用工程代码如下：

pod 'YXFilmSelectView', '~> 0.0.1'

2、使用方法

 YXFilmSelectView *filmSelectView = [[YXFilmSelectView alloc] initViewWithImageArray:imageArray]; 
filmSelectView.delegate = self; 
[self.view addSubview:filmSelectView];

3、提供YXFilmSelectViewDelegate代理，用于每一个Item处于选中状态的处理。

- (void)itemSelected:(NSInteger)index{ 
_containerView.backgroundColor = _colorArray[index%_colorArray.count]; 
_showLabel.text = [NSString stringWithFormat:@"%zi",index];
}

4、Demo下载地址

github 下载地址
如果对你有点帮助，star一下吧。

5、联系方式

新浪微博
github
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