滑动手势问题

Question

我在图像视图上添加了两个swipegesture，一个用于右，一个用于左。我想要的是，使用时单击任何图像并向左或向右滑动，图像就会像我们在手机图库中那样相应地更改。但是当我向左或向右滑动时，一次图像更改之后什么也没有发生。所有这些图像都来自数组，数组名称为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"]];
    }

Answer 1

问题在于当imageindex == 0时应停止递减，而当index == getdataarray.count时应停止递增

- (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"]];
}

然后，您应该使用&&运算符而不是OR运算符

Answer 2

selectimageIndex是什么？我从selectimageIndex放问题；

由于您一次滑动了图像视图，因此方法“ handleswipe：”将运行一次。所以imageindex始终等于selectimageIndex。请中断一点以查看imageindex值。

-

-重新编辑

 -(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"]];
   }
  }