1

所以我有一个像照片库一样的应用程序，我正在实现用户删除图像的能力。这是设置：我有 9 个 UIImageView、imageView、imageView2 等。我还有一个“编辑”按钮和一个 tapGesture 操作方法。我将一个 Tap Gesture Recognizer 拖到我在 IB 中的视图上，并将其附加到每个 UIImageViews 上。我还将 tapGesture 操作方法附加到每个 UIImageViews。理想情况下，我希望该方法仅在按下“编辑”按钮时才变为活动状态。当用户点击编辑，然后点击他们要删除的图片时，我希望出现一个 UIAlertView，询问他们是否确定要删除它。这是我正在使用的代码：

- (IBAction)editButtonPressed:(id)sender {
    editButton.hidden = YES;
    backToGalleryButton.hidden = NO;
    tapToDeleteLabel.hidden = NO;
}

- (IBAction)tapGesture:(UITapGestureRecognizer*)gesture
{

    UIAlertView *deleteAlertView = [[UIAlertView alloc] initWithTitle:@"Delete"
                                                              message:@"Are you sure you want to delete this photo?"
                                                             delegate:self
                                                    cancelButtonTitle:@"No"
                                                    otherButtonTitles:@"Yes", nil];
    [deleteAlertView show];

    if (buttonIndex != [alertView cancelButtonIndex]) {

        UIImageView *view = [self.UIImageView];
        if (view) {
            [self.array removeObject:view];
        }


        CGPoint tapLocation = [gesture locationInView: self.view];
        for (UIImageView *imageView in self.view.subviews) {
            if (CGRectContainsPoint(self.UIImageView.frame, tapLocation)) {
                ((UIImageView *)[self.view]).image =nil;
 }

}
        [self.user setObject:self.array forKey:@"images"];
}
}

这段代码显然充满了错误：这一行的“使用未声明的标识符按钮索引”：if (buttonIndex != [alertView cancelButtonIndex])

此行上的“在 PhotoViewController 类型的对象上找不到属性 UIImageView”UIImageView *view = [self.UIImageView];

和这一行的“预期标识符”((UIImageView *)[self.view]).image =nil;

我对编程很陌生，我很惊讶我能做到这一点。所以，我只是想弄清楚我需要如何编辑我的代码以使错误消失，并且只要点击 9 个图像视图之一就可以使用它，并且只有在首先按下编辑按钮。我之前使用标签，效果很好，但是我通过 NSData 保存图像，所以我不能再使用标签了。非常感谢任何帮助，谢谢！

4

3 回答 3

2

首先，您不想将点击手势附加到图像视图。此外，如果您将拥有超过 9 个图像，您可能需要滚动视图，或单独处理滚动。首先，删除该手势识别器及其所有连接。

接下来，确定您将用作画廊画布的视图类型。一个简单的视图，或者一个滚动视图，或者其他什么......现在并不重要，只是为了让它工作。您想将该视图按住 ctrl 并拖动到您的界面定义中，因此它会为该视图放置一个 IBOutlet（这样您就可以在代码中引用它）。

你将把你的 ImageViews 放到我刚才提到的视图上。

您可以为手势识别器设置一个内部标志，但它也有一个属性，可以随时启用/禁用它。因此，您可以相当轻松地使其处于活动/非活动状态。

您要做的就是将一个轻击手势识别器放到您的控制器上，并将其连接到控制器的实现部分。它将生成一个用于处理识别器的存根。它将“一般”解释控制器的点击，并在视图上进行点击时调用您的代码。

还有一些代码...

在滚动视图中为“新”图像创建一个框架。

- (CGRect)frameForData:(MyData*)data atIndex:(NSUInteger)idx
{
    CGPoint topLeft;
    int row = idx / 4;
    int col = idx % 4;
    topLeft.x = (col+1)*HORIZ_SPACING + THUMBNAIL_WIDTH * (col);
    topLeft.y = (row+1)*VERT_SPACING + THUMBNAIL_HEIGHT * (row);
    return CGRectMake(topLeft.x, topLeft.y, THUMBNAIL_WIDTH, THUMBNAIL_HEIGHT);
}

为每条元数据创建一个图像视图和一个小边框。

- (UIImageView*)createImageViewFor:(MetaData*)metadata
{
    UIImageView *imageView = [[UIImageView alloc] initWithImage:metadata.lastImage];
    imageView.frame = CGRectMake(0, 0, THUMBNAIL_WIDTH, THUMBNAIL_HEIGHT);;
    imageView.layer.borderColor = [[UIColor blackColor] CGColor];
    imageView.layer.borderWidth = 2.0;
    imageView.userInteractionEnabled = YES;
    return imageView;
}

这是创建视图并将其添加到父级的地方...

    imageView = [self createImageViewFor:metadata];
    //[data.imageView sizeToFit];

    // Make sure the scrollView contentSize represents the data
    CGRect lastFrame = [self frameForData:data atIndex:self.data.count-1];
    CGFloat newHeight = lastFrame.origin.y + lastFrame.size.height;
    if (self.bookshelfScrollView.contentSize.height < newHeight) {
        CGSize newSize = self.bookshelfScrollView.contentSize;
        newSize.height = newHeight;
        self.bookshelfScrollView.contentSize = newSize;
    }
    [self.bookshelfScrollView addSubview:data.imageView];

因此，您只需创建每个框架，将它们添加到视图中，您唯一需要做的就是在它们上启用用户交互，否则滚动视图不允许手势通过。

好的......看看你发布的代码......因为你没有说它有什么问题......很难说......下面是你的代码......我的评论是，嗯，评论...... .

- (IBAction)editButtonPressed:(id)sender {
    editButton.hidden = YES;
    backToGalleryButton.hidden = NO;
    tapToDeleteLabel.hidden = NO;
}
- (IBAction)tapGesture:(UITapGestureRecognizer*)gesture
{
    // I don't think I'd do this here, but it shouldn't cause "problems."
    UIAlertView *deleteAlertView = [[UIAlertView alloc] initWithTitle:@"Delete"
                                                              message:@"Are you sure you want to delete this photo?"
                                                             delegate:self
                                                    cancelButtonTitle:@"No"
                                                    otherButtonTitles:@"Yes", nil];
    [deleteAlertView show];

    // In your controller, you have the main view, which is the view
    // on which you added your UIViews.  You need that view.  Add it as an IBOutlet
    // You should know how to do that...  ctrl-drag to the class INTERFACE source.
    // Assuming you name it "galleryView"

    // Take the tap location from the gesture, and make sure it is in the
    // coordinate space of the view.  Loop through all the imageViews and
    // find the one that contains the point where the finger was taped.
    // Then, "remove" that one from its superview...
    CGPoint tapLocation = [gesture locationInView: self.galleryView];
    for (UIImageView *imageView in self.galleryView.subviews) {
        if (CGRectContainsPoint(imageView.frame, tapLocation)) {
            [imageView removeFromSuperview];
        }
    }
}
于 2012-04-10T23:42:15.637 回答
1

就个人而言，在我的小照片库中，我绕过了所有手势识别器，方法是用控件替换UIImageView控件UIButton，为按钮设置图像属性，就像为UIImageView. 它看起来一模一样，但是你可以免费点击缩略图，根本不需要手势。

所以，我的视图只有一个UIScrollView，我以编程方式将我的图像添加为按钮，并为按钮控件设置图像，例如：

- (void)loadImages
{
    listOfImages = [ImageData newArrayOfImagesForGallery:nil];

    // some variables to control where I put my thumbnails (which happen to be 76 x 76px)

    int const imageWidth = 76;
    int const imageHeight = imageWidth;
    NSInteger imagesPerRow;
    NSInteger imagePadding;
    NSInteger cellWidth;
    NSInteger cellHeight;

    // some variables to keep track of where I am as I load in my images

    int row = 0;
    int column = 0;
    int index = 0;

    // add images to navigation bar

    for (ImageData *item in listOfImages)
    {
        // figure out what row and column I'm on

        imagesPerRow = self.view.frame.size.width / (imageWidth + 2);
        imagePadding = (self.view.frame.size.width - imageWidth*imagesPerRow) / (imagesPerRow + 1);
        cellWidth = imageWidth + imagePadding;
        cellHeight = imageHeight + imagePadding;

        // this is how I happen to grab my UIImage ... this will vary by implementation

        UIImage *thumb = [item imageThumbnail];

        // assuming I found it...

        if (thumb)
        {
            // create my button and put my thumbnail image in it

            UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
            button.frame = CGRectMake(column * cellWidth  + imagePadding, 
                                      row    * cellHeight + imagePadding, 
                                      imageWidth, 
                                      imageHeight);
            [button setImage:thumb forState:UIControlStateNormal];
            [button addTarget:self
                       action:@selector(buttonClicked:)
             forControlEvents:UIControlEventTouchUpInside];
            button.tag = index++;
            [[button imageView] setContentMode:UIViewContentModeScaleAspectFit];

            // add it to my view

            [scrollView addSubview:button];

            // increment my column (and if necessary row) counters, making my scrollview larger if I need to)

            if (++column == imagesPerRow) 
            {
                column = 0;
                row++;
                [scrollView setContentSize:CGSizeMake(self.view.frame.size.width, (row+1) * cellHeight + imagePadding)];
            }
        }
    }
}

// I also have this in case the user changes orientation, so I'll move my images around if I need to

- (void)rearrangeImages
{
    if (!listOfImages)
    {
        [self loadImages];
        return;
    }

    // a few varibles to keep track of where I am

    int const imageWidth = 76;
    int const imagesPerRow = self.view.frame.size.width / (imageWidth + 2);
    int const imageHeight = imageWidth;
    int const imagePadding = (self.view.frame.size.width - imageWidth*imagesPerRow) / (imagesPerRow + 1);
    int const cellWidth = imageWidth + imagePadding;
    int const cellHeight = imageHeight + imagePadding;

    NSArray *buttons = [[NSArray alloc] initWithArray:[scrollView subviews]];

    int row;
    int column;
    int index;

    CGRect newFrame;

    // iterate through the buttons

    for (UIView *button in buttons)
    {
        index = [button tag];

        if ([button isKindOfClass:[UIButton class]] && index < [listOfImages count])
        {
            // figure out where the button should go

            row = floor(index / imagesPerRow);
            column = index % imagesPerRow;
            newFrame = CGRectMake(column * cellWidth  + imagePadding, 
                                  row    * cellHeight + imagePadding, 
                                  imageWidth, 
                                  imageHeight);

            // if we need to move it, then animation the moving

            if (button.frame.origin.x != newFrame.origin.x || button.frame.origin.y != newFrame.origin.y)
            {
                [UIView animateWithDuration:0.33 animations:^{
                    [button setFrame:newFrame];
                }];
            }
        }
    }

    NSInteger numberOfRows = floor(([listOfImages count] - 1) / imagesPerRow) + 1;

    [scrollView setContentSize:CGSizeMake(self.view.frame.size.width, numberOfRows * cellHeight + imagePadding)];
}

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation
{
    [self rearrangeImages];
}

希望这能让您了解如何UIButton以编程方式添加一个作为图库中的图像。我试图即时编辑它，所以如果我在此过程中引入任何错误，我提前道歉，但它应该让你了解你可以想象的事情......我删除了我的代码以执行此操作单独的 GCD 队列（我这样做是因为我有接近 100 个图像，并且在主队列上这样做太慢了。）

无论如何，您可以创建您的buttonClicked方法来显示您的UIAlertView.

- (void)buttonClicked:(UIButton *)sender
{
     if (inEditMode)
     {
         // create your UIAlterView using [sender tag] to know which image you tapped on
     }
}

最后，您的 上有两个按钮UIAlertView，但您似乎没有检查用户单击了哪个按钮。您的视图控制器应该是一个UIAlterViewDelegate，您已经在其中定义了alertView:clickedButtonAtIndex将执行您的实际编辑步骤的视图控制器。

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
     // ok, will do what I need to do with whatever the user tapped in my alertview
}
于 2012-04-11T00:30:21.127 回答
0

我能想到的最简单的事情是默认禁用手势，然后在按下编辑按钮后启用手势。这样，图片只有在“编辑”模式下才会响应点击手势识别器。

于 2012-04-10T23:38:41.340 回答