所以我的应用程序就像一个照片库，我正在实现用户删除图像的能力。这是设置：我有9个UIImageViews，imageView，imageView2等。我还有一个“编辑”按钮和一个tapGesture动作方法。我将Tap Gesture Recognizer拖到我在IB中的视图上，并将其附加到每个UIImageViews上。我还将tapGesture动作方法附加到每个UIImageViews。理想情况下，我希望该方法仅在按下“编辑”按钮时变为活动状态。当用户点击编辑，然后点击他们想要删除的图片时，我想要一个UIAlertView出现，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"];
}
}
这段代码显然有很多错误：
“使用未声明的标识符按钮索引”在此行：if (buttonIndex != [alertView cancelButtonIndex])
“在PhotoViewController类型的对象上找不到属性UIImageView”这一行UIImageView *view = [self.UIImageView];
此行((UIImageView *)[self.view]).image =nil;
我对编程很新，我很惊讶我甚至做到了这一点。所以，我只想弄清楚我需要如何编辑我的代码以便错误消失，并且只要轻触9个图像视图中的一个就可以使用它，并且这样只有在首先按下编辑按钮。我之前使用的是标签，效果很好，但是我通过NSData保存图像，所以我再也不能使用标签了。非常感谢任何帮助，谢谢！
答案 0 :(得分：2)
首先，您不希望将点击手势附加到图像视图。此外，如果要包含9个以上的图像，则可能需要滚动视图或单独处理滚动。首先，删除手势识别器及其所有连接。
接下来，确定您将用作图库画布的视图类型。一个简单的视图，或ScrollView，或者其他......它现在并不重要，只是让它工作。您想要将该视图拖放到您的界面定义中，因此它会删除视图的IBOutlet（这样您就可以在代码中引用它）。
您将把ImageView放到我刚刚提到的视图上。
您可以为手势识别器设置内部标志，但它也有一个可以随时启用/禁用它的属性。因此，您可以非常轻松地使其处于活动/非活动状态。
您要做的就是将单个手势识别器放到控制器上，然后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。它将为控制器“一般”解释抽头，并在视图上点击时调用您的代码。
更多代码......
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级...
的位置 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，您只需创建每个帧，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......因为你没有说出它有什么问题......很难说......下面是你的代码...我的评论是，好吧，注释...
- (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];
}
}
}
答案 1 :(得分：1)
就我个人而言，在我的小照片库中，我用UIImageView控件替换UIButton控件，绕过所有的手势识别器，为UIImageView设置按钮的图像属性。 1}}。它看起来完全相同，但随后您可以免费使用缩略图，无需任何手势。
所以，我的视图只有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。我试着动态编辑这个，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...我删除了我的代码来做到这一点单独的GCD队列（我这样做是因为我有近100张图像，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，UIAlertView上有两个按钮，但您似乎没有检查用户点击的按钮。您的视图控制器应该是UIAlterViewDelegate，您已在其中定义了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
}
答案 2 :(得分：0)
我能想到的最简单的事情是默认情况下禁用手势，然后在点击编辑按钮后启用手势。这样，如果图片处于“编辑”模式，图片将仅响应敲击手势识别器。