滑动手势问题

Posted 2023-03-08

【中文标题】滑动手势问题

【英文标题】：Swipe Gesture issue

【发布时间】：2018-08-03 10:46:20

【问题描述】：

我在图像视图中添加了两个滑动手势。一个用于右侧，一个用于左侧。我想要的是，当使用单击任何图像并向左或向右滑动时，图像会相应地改变，就像我们在手机图库中所做的那样。但是当我向左或向右滑动时，只有一次图像更改，之后没有任何反应。所有这些图像都来自数组，数组名称是 getdataarray。这是我的代码

.h 文件

@property (strong, nonatomic) IBOutlet UISwipeGestureRecognizer *rightgesture;

@property (strong, nonatomic) IBOutlet UISwipeGestureRecognizer *leftgesture;
- (IBAction)handleswipe:(UISwipeGestureRecognizer *)sender;

.m 文件

-(void)viewdidload 


_rightgesture= [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleswipe:)];

    _leftgesture= [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleswipe:)];


- (IBAction)handleswipe:(UISwipeGestureRecognizer *)sender 

    int imageindex = (int) selectedimageindex;

    UISwipeGestureRecognizerDirection direction = [(UISwipeGestureRecognizer *) sender direction];

    switch (direction) 

        case UISwipeGestureRecognizerDirectionLeft:
            imageindex++;
            break;
        case UISwipeGestureRecognizerDirectionRight:
            imageindex--;
            break;

        default:
            break;
    

    if (imageindex > -1 || imageindex < getdataarray.count) 
        [fullimageview sd_setImageWithURL:[getdataarray objectAtIndex: imageindex] placeholderImage:[UIImage imageNamed:@"placeholder.png"]];
    

【参考方案1】：

什么是 selectimageIndex ？我从 selectimageIndex 解决问题；

因为你刷了一次 imageview，方法 'handleswipe:' 将运行一次。所以 imageindex 总是等于 selectimageIndex 。请断点查看imageindex值。

--

- 再次编辑

 -(void)viewdidload 


_rightgesture= [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleswipe:)];

    _leftgesture= [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleswipe:)];

// this code changed. _imageindex is global property .
    _imageindex = (int) selectedimageindex;


- (IBAction)handleswipe:(UISwipeGestureRecognizer *)sender 

    UISwipeGestureRecognizerDirection direction = [(UISwipeGestureRecognizer *) sender direction];

    switch (direction) 

        case UISwipeGestureRecognizerDirectionLeft:
             if (_imageindex<getdataarray.count) _imageindex++; break;
        case UISwipeGestureRecognizerDirectionRight:
             if (_imageindex>0)_imageindex--;   break;
       default: break;
   

   if (_imageindex > -1 && _imageindex < getdataarray.count) 
       [fullimageview sd_setImageWithURL:[getdataarray objectAtIndex:_imageindex] placeholderImage:[UIImage imageNamed:@"placeholder.png"]];
   
  

【讨论】：

selectedimageindex 是用户点击的图像的索引号，这是显示图像的集合视图单元格 getselectedimageindexno = (int) indexPath.row;

int imageindex = (int) selectedimageindex;看看这条线。你的 imageindex 总是等于 selectedimageindex 。因为 selectedimageindex 不能改变，所以你滑动 imageview ，imageindex 可以改变。

那么我该如何解决这个问题？

我已经编辑了答案，希望能解决你的问题。

【参考方案2】：

问题在于，当您到达 imageindex ==0 时，您应该停止递减，当您到达 index == getdataarray.count 时，您应该停止递增

- (IBAction)handleswipe:(UISwipeGestureRecognizer *)sender 

int imageindex = (int) selectedimageindex;

UISwipeGestureRecognizerDirection direction = [(UISwipeGestureRecognizer *) sender direction];

switch (direction) 

    case UISwipeGestureRecognizerDirectionLeft:
        if imageindex<0
        
             imageindex++;
        
        imageindex++;
        break;
    case UISwipeGestureRecognizerDirectionRight:
        if imageindex>getdataarray.count
        
             imageindex--;
        

        break;

    default:
        break;


if (imageindex > -1 && imageindex < getdataarray.count) 
    [fullimageview sd_setImageWithURL:[getdataarray objectAtIndex: imageindex] placeholderImage:[UIImage imageNamed:@"placeholder.png"]];

并且你应该使用 && 运算符而不是 OR 运算符

【讨论】：

不工作 .. 仍然是同样的问题，只有在第一次刷卡工作之后没有任何反应