Question

我的应用程序就像一个照片库。我正在实现用户删除照片的功能，在每个UIImageView上放置一个不可见的按钮，并在点击按钮时调用removeObject。这段代码工作得很好，但它依赖于标签。我需要在界面构建器中标记每个UIImageView / UIButton才能使其正常工作。所以，我现在正试图以我的标签仍然可用的方式保存图像，这不包括使用NSData。

所以我现在完全迷失了该怎么做。我是非常非常新的编程，我很惊讶我甚至做到了这一点。关于如何编辑我的代码以使其工作的任何帮助或建议非常感谢，谢谢！

以下是我的整个文件仅供参考：

- (IBAction)grabImage {
    self.imgPicker = [[UIImagePickerController alloc] init];
    self.imgPicker.delegate = self;
    self.imgPicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad) {
        _popover = [[UIPopoverController alloc] initWithContentViewController:imgPicker];
        [_popover presentPopoverFromRect:self.imageView.bounds inView:self.imageView permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
    } 

    else {
        [self presentModalViewController:imgPicker animated:YES];
    }
    [self.imgPicker resignFirstResponder];
}
// Sets the image in the UIImageView
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)img editingInfo:(NSDictionary *)editInfo {
    if (imageView.image == nil) {
        imageView.image = img;

        [self.array addObject:imageView.image];

        [picker dismissModalViewControllerAnimated:YES];
        [self.popover dismissPopoverAnimated:YES];
        return;

    }

    if (imageView2.image == nil) {
        imageView2.image = img;
        NSLog(@"The image is a %@", imageView);
        [self.array addObject:imageView2.image];

        [picker dismissModalViewControllerAnimated:YES];
        [self.popover dismissPopoverAnimated:YES];
        return;
    }

    if (imageView3.image == nil) {
        imageView3.image = img;

        [self.array addObject:imageView3.image];

        [picker dismissModalViewControllerAnimated:YES];
        [self.popover dismissPopoverAnimated:YES];
        return;
    }

    if (imageView4.image == nil) {
        imageView4.image = img;

        [self.array addObject:imageView4.image];

        [picker dismissModalViewControllerAnimated:YES];
        [self.popover dismissPopoverAnimated:YES];
        return;
    }
    if (imageView5.image == nil) {
        imageView5.image = img;

        [self.array addObject:imageView5.image];

        [picker dismissModalViewControllerAnimated:YES];
        [self.popover dismissPopoverAnimated:YES];
        return;
    }

- (void)applicationDidEnterBackground:(UIApplication*)application {
    NSLog(@"Image on didenterbackground: %@", imageView);

    [self.array addObject:imageView.image];
    [self.array addObject:imageView2.image];
    [self.array addObject:imageView3.image];
    [self.array addObject:imageView4.image];
    [self.array addObject:imageView5.image];

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

}

- (void)viewDidLoad
{
    self.user = [NSUserDefaults standardUserDefaults];
    NSLog(@"It is %@", self.user);
    self.array = [[self.user objectForKey:@"images"]mutableCopy];
    imageView.image = [[self.array objectAtIndex:0] copy];
    imageView2.image = [[self.array objectAtIndex:1] copy];
    imageView3.image = [[self.array objectAtIndex:2] copy];
    imageView4.image = [[self.array objectAtIndex:3] copy];
    imageView5.image = [[self.array objectAtIndex:4] copy];



    UIApplication *app = [UIApplication sharedApplication];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(applicationDidEnterBackground:)
                                                 name:UIApplicationDidEnterBackgroundNotification
                                               object:app];

    [super viewDidLoad];

}


// This is when the user taps on the image to delete it.
- (IBAction)deleteButtonPressed:(id)sender {
    NSLog(@"Sender is %@", sender);
    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];

    int imageIndex = ((UIButton *)sender).tag;
    deleteAlertView.tag = imageIndex;
}

- (UIImageView *)viewForTag:(NSInteger)tag {
    UIImageView *found = nil;
    for (UIImageView *view in self.array) {
        if (tag == view.tag) {
            found = view;
            break;
        }
    }
    return found;
}

- (void)alertView: (UIAlertView *) alertView 
clickedButtonAtIndex: (NSInteger) buttonIndex
{


    if (buttonIndex != [alertView cancelButtonIndex]) {
        NSLog(@"User Clicked Yes. Deleting index %d of %d", alertView.tag, [array count]);
        NSLog(@"The tag is %i", alertView.tag);

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

        NSLog(@"After deleting item, array count  = %d", [array count]);
        NSLog(@"Returned view is :%@, in view: %@", [self.view viewWithTag:alertView.tag], self.view);
        ((UIImageView *)[self.view viewWithTag:alertView.tag]).image =nil;
    }

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

@end

Answer 1

之前的评论是准确的;请考虑一下如何扩大规模。

也就是说，你需要以某种方式存储和加载图像，这总是意味着将你的UIImage对象转换为NSData。无论您将它们存储在NSUserDefaults，文件还是核心数据中，都适用。

UIImage支持NSCoding，因此您可以使用它。了解如何使用它，因为您最终将需要它。或者，如果您知道自己总是希望使用PNG或JPEG格式，则可以使用UIImagePNGRepresentation(UIImage *image)和UIImageJPEGRepresentation(UIImage *image, CGFloat compressionQuality)函数。要将NSData对象转换回UIImage，请使用[UIImage imageWithData:NSData*]以下是applicationDidEnterBackground中可能包含的内容：

NSMutableArray *dataArray = [NSMutableArray array];
[dataArray addObject:UIImagePNGRepresentation(imageView.image)];
[dataArray addObject:UIImagePNGRepresentation(imageView2.image)];
[dataArray addObject:UIImagePNGRepresentation(imageView3.image)];
[self.user setObject:dataArray forKey:@"images"];
[self.user synchronize];

然后，在viewDidLoad中检索这些：

[self.array removeAllObjects];
NSArray *dataArray = [self.user objectForKey:@"images"];
for (NSData *imageData in dataArray)
    [self.array addObject:[UIImage imageWithData:imageData]];

这将解决您当前的问题，但请不要将其视为永久解决方案。考虑：

将图像存储在文件或核心数据中，因为NSUserDefaults不是应该有大量的内容。
使用UITableView显示图像，这样您就可以拥有任意数字而不是三个硬编码。
如果UITableView没有您需要的布局，请创建自定义 UIView子类，显示图像数组并适当响应点击。
确保您的应用程序可以检测到它的所有方式暂停或关闭。你可能并不总是得到 ApplicationDidEnterBackground通知，或者您可能没有时间发生后保存所有数据。如果你有多个 UIViewControllers，这个可以在没有应用程序的情况下卸载本身接收通知。

Answer 2

您似乎正在使用标记，因此您可以识别正在选择的图像视图。每个图像顶部都有一个“隐形”按钮？是对的吗？我认为你可以处理一个水龙头，它会选择通过按钮显示的图像吗？

有很多方法可以做到这一点，但一个简单的解决方案是只识别点按，然后“找到”该点按下方的图像视图。从故事板中将UITapGestureRecognizer放到控制器上。按住Ctrl键将其拖动到控制器的代码中，它将创建一个操作方法。填写这样的东西......

  - (IBAction)tapGesture:(UITapGestureRecognizer*)gesture
  {
    CGPoint tapLocation = [gesture locationInView: self.galleryView];
    for (UIImageView *imageView in self.galleryView.subviews) {
      if (CGRectContainsPoint(imageView.frame, tapLocation)) {
        // This is the imageView that was tapped on!
        // Do whatever you want with it now that you found it.
      }
    }
  }

在iOS中保存图像

2 个答案: