Question

我通过一些相应的图像创建了一个教程，并在其上添加了一个页面控件。另外，我添加了一个滑动手势，通过更改图片来响应。在下面的代码中，定义了一个开关盒，以便根据滑动方向（左/右）决定哪个图像和点应该是下一个。

- (IBAction)handleSwipe:(UISwipeGestureRecognizer *)sender
{
//    NSLog(@"swiped");
    NSArray *images;

    if (self.selectedRow == 0) {
        images = [[NSArray alloc] initWithObjects:@"w8.JPG",@"w7.JPG",@"w6.JPG",@"w5.JPG",@"w4.JPG",@"w3.JPG", @"w2.JPG", @"w1.JPG" ,@"w9.JPG", nil];

        self.pageControl.hidden = NO;
        [self.pageControl setNumberOfPages:9];

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

        switch (direction) {
            case UISwipeGestureRecognizerDirectionRight:
                if (pageController == 0 || imageIndex == 8)
                {
                    self.Oops = [[UIAlertView alloc] initWithTitle:@"Oops!" message:@"You cannot swipe to the left, there are not any previous steps." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
                    [self.Oops show];
                }
                else {
                    [self.pageControl setCurrentPage:pageController - 1];
                    pageController = pageController - 1;
                }
                imageIndex++;
                break;
            case UISwipeGestureRecognizerDirectionLeft:
                if (pageController < 8 && pageController >= 0) {
                    [self.pageControl setCurrentPage:pageController];
                    pageController = pageController + 1;
                }
                else {
                    [self.pageControl setCurrentPage: pageController ];
                    pageController = 0;
                }
                imageIndex--;
                break;
            default:
                break;
        }
        NSLog(@"pagecontroller is %li and imageIndex is %li " , pageController, imageIndex);
        imageIndex = (imageIndex < 0) ? ([images count] - 1): imageIndex % [images count];
        self.imageView.image = [UIImage imageNamed:[images objectAtIndex:imageIndex]];
    }

正如您在代码中看到的那样，有一个NSLog;当我运行应用程序时，一切正常，但是当我向右滑动以查看上一张图像时，尽管NSLog显示所有点和图像索引都正确变化，我们看到上一张图像，但这些点不会改变。再次向右滑动，点会改变，但由于必须分类的图像和点的顺序变得无序，例如最后一个图像用第一个点显示，所以它会变得迟。我确定我的算法是正确的，因为我用NSLog检查了它，并且在向右滑动之前一切正常。有什么想法吗？

我稍微更改了代码：

 switch (direction) {
            case UISwipeGestureRecognizerDirectionRight:
                if (pageController != 0 && imageIndex != 9) {
                    [self.pageControl setCurrentPage:(pageController - 1)];
                    pageController --;
                    imageIndex++;
                }
                break;
            case UISwipeGestureRecognizerDirectionLeft:
                if (pageController <= 8 && pageController >= 0) {
                    [self.pageControl setCurrentPage:pageController];
                    pageController = pageController + 1;
                    imageIndex--;
                }
                break;
            default:
                break;
        }

现在唯一的问题是，当我向不同的方向滑动时，页面控件会对当前点进行两次计数。

Answer 1

您的imageIndex++和imageIndex--行位置错误。（例如，如果pageController已经为0，则可能不想更改图像）。将它们移动到：

- (IBAction)handleSwipe:(UISwipeGestureRecognizer *)sender
{
//    NSLog(@"swiped");
    NSArray *images;
    
    if (self.selectedRow == 0) {
        images = [[NSArray alloc] initWithObjects:@"w8.JPG",@"w7.JPG",@"w6.JPG",@"w5.JPG",@"w4.JPG",@"w3.JPG", @"w2.JPG", @"w1.JPG" ,@"w9.JPG", nil];
        
        self.pageControl.hidden = NO;
        [self.pageControl setNumberOfPages:9];
        
        UISwipeGestureRecognizerDirection direction = [(UISwipeGestureRecognizer *) sender direction];
        
        switch (direction) {
            case UISwipeGestureRecognizerDirectionRight:
                if (pageController == 0 || imageIndex == 8)
                {
                    self.Oops = [[UIAlertView alloc] initWithTitle:@"Oops!" message:@"You should turn over to the left." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
                    [self.Oops show];
                }
                else {
                    [self.pageControl setCurrentPage:pageController - 1];
                    pageController = pageController - 1;
                    imageIndex++;
                }
                break;
            case UISwipeGestureRecognizerDirectionLeft:
                if (pageController < 8 && pageController >= 0) {
                    [self.pageControl setCurrentPage:pageController];
                    pageController = pageController + 1;
                    imageIndex--;
                }
                else {
                    [self.pageControl setCurrentPage: pageController ];
                    pageController = 0;
                }
                break;
            default:
                break;
        }
        NSLog(@"pagecontroller is %li and imageIndex is %li " , pageController, imageIndex);
        imageIndex = (imageIndex < 0) ? ([images count] - 1): imageIndex % [images count];
        self.imageView.image = [UIImage imageNamed:[images objectAtIndex:imageIndex]];
    }

在修改后的代码中，我认为您需要以不同的方式设置页面控件（到pageController + 1）以向左滑动：

switch (direction) {
        case UISwipeGestureRecognizerDirectionRight:
            if (pageController != 0 && imageIndex != 9) {
                [self.pageControl setCurrentPage:(pageController - 1)];
                pageController --;
                imageIndex++;
            }
            break;
        case UISwipeGestureRecognizerDirectionLeft:
            if (pageController <= 8 && pageController >= 0) {
                [self.pageControl setCurrentPage:pageController+1];
                pageController = pageController + 1;
                imageIndex--;
            }
            break;
        default:
            break;
    }

向右滑动，页面控件的当前页面会发生变化但点不会

1 个答案: