滑动手势问题

Question

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 phone 图库中所做的那样。但是当我向左或向右滑动一次时，图像发生变化，之后什么也没有发生。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"]];
    }

Answer 1

问题在于，当您到达 imageindex ==0 时，您应该停止递减，而当您到达 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"]];
}

And 你应该使用 && 运算符而不是 OR 运算符

Answer 2

什么是 selectimageIndex ？我从 selectimageIndex 解决问题；

因为您滑动图像视图一次，方法 'handleswipe:' 将运行一次。所以 imageindex 总是等于 selectimageIndex 。请打个分看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"]];
   }
  }

滑动手势问题

Swipe Gesture issue

objective-c

ios

uiswipegesturerecognizer

- 再次编辑