[英]iOS: TapGestureRecognizer Issues
所以我有一个行为类似于照片库的应用程序,并且我正在实现用户删除图像的功能。 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 Tap Gesture Recognizer 拖到我在 IB 中的视图上,并将其附加到每个 UIImageView。 我还将 tapGesture 操作方法附加到每个 UIImageView。 理想情况下,我希望该方法仅在按下“编辑”按钮时才激活。 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:“使用未声明的标识符按钮索引”这一行: if (buttonIndex != [alertView cancelButtonIndex])
“属性 UIImageView 在类型 PhotoViewController 的 object 上找不到”这一行UIImageView *view = [self.UIImageView];
以及这一行的“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,以便消除错误 go,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。 我之前使用过标签,效果很好,但我通过 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!
首先,您不想将点击手势附加到图像视图。 此外,如果您要拥有超过 9 张图像,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,确定您将使用哪种类型的视图作为您的图库 canvas。一个简单的视图,或一个滚动视图,或任何...现在并不重要,只是让它工作。 您想要将该视图按住 trl 并拖动到您的接口定义中,因此它会为该视图删除一个 IBOutlet(这样您就可以在代码中引用它)。
您将把您的 ImageView 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,您可以随时启用/禁用它。 因此,您可以很容易地使其处于活动/非活动状态。
您要做的就是将单个点击手势识别器放到您的 controller 上,并将其连接到 controller 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 controller 的点击,并在视图上进行点击时调用您的代码。
一些更多的代码...
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);
}
为每个元数据和一个小边框创建一个图像视图。
- (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视图的地方...
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,否则滚动视图将不允许手势通过。
好的...查看您发布的代码...因为您没有说它有什么问题...很难说...下面是您的代码...我的评论是,好吧,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];
}
}
}
就个人而言,在我的小照片库中,我通过将UIImageView
控件替换为UIButton
控件来绕过所有手势识别器,像为UIImageView
一样设置按钮的图像属性。 它看起来一模一样,但是你可以免费获得点击缩略图的功能,根本不需要任何手势。
因此,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以编程方式添加UIButton
以充当图库中的图像。 我试图即时编辑它,所以如果我在这个过程中引入了任何错误,我会提前道歉,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在单独的 GCD 队列(我这样做是因为我有将近 100 张图像,并且在主队列上这样做太慢了。)
无论如何,您可以创建buttonClicked
方法来显示UIAlertView
。
- (void)buttonClicked:(UIButton *)sender
{
if (inEditMode)
{
// create your UIAlterView using [sender tag] to know which image you tapped on
}
}
最后,您的UIAlertView
上有两个按钮,但您似乎没有检查用户单击了哪个按钮。 您的视图 controller 应该是一个UIAlterViewDelegate
,您在其中定义了alertView:clickedButtonAtIndex
,它将执行您的实际编辑步骤。
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
// ok, will do what I need to do with whatever the user tapped in my alertview
}
我能想到的最简单的事情就是默认禁用手势,然后在按下编辑按钮后启用手势。 这样,如果图片处于“编辑”模式,则图片只会响应点击手势识别器。
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