提问



我写这篇应用程序的这一部分时遇到了很多问题,我确信这里的人都厌倦了我,所以我将尝试在这篇文章中解决我的所有问题。我正在开发一个行为类似于照片库的应用程序,我正在实施让用户从其库中删除照片的选项。为了做到这一点,我决定在每张照片上放置一个隐形按钮。当用户点击编辑按钮时,每张图片上的隐藏删除按钮变为Activity状态。为简单起见,我在每个隐藏按钮上使用相同的IBOutlet,并且我在Interface Builder中正确标记了每个按钮。当用户点击图片上的按钮时,会出现警告视图,询问他们是否确实要删除它。如果他们单击是,我调用removeObjectAtIndex并从UI中删除图像。但是,当我在警报视图中单击是时,我从Xcode收到错误说明:


2012-04-04 11:26:40.484 AppName [[608:f803]] - [[UIButton setImage:]]:无法识别的选择器发送到实例0x6a922c0


2012-04-04 11:26:40.485 AppName [[608:f803]] 由于未捕获的异常NSInvalidArgumentException而终止应用程序,原因: - [[UIButton setImage:]]:发送到无法识别的选择器实例0x6a922c0 *


我一直试图弄清楚导致这种情况几个小时的现在无济于事。我没有在我的代码中的任何地方设置UIButton的图像。我在IB中做过,但我只是将按钮类型设置为Custom,使它们看起来不可见。我将在下面发布我的整个文件,我在代码中找不到任何问题,所以非常感谢任何帮助!谢谢。
编辑以下是代码的当前版本:


    - (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 = [NSMutableArray arrayWithObject:[NSData dataWithData:UIImagePNGRepresentation(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:[NSData dataWithData:UIImagePNGRepresentation(imageView2.image)**];

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

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

        [self.array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView3.image)**];

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

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

        [self.array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView4.image)**];

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

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        self.title = NSLocalizedString(@"Photo Gallery", @"Photo Gallery");
        self.tabBarItem.image = [UIImage imageNamed:@"42-photos.png"];
    }
    return self;
}
////start of saving////


- (void)applicationDidEnterBackground:(UIApplication*)application {
    NSLog(@"Image on didenterbackground: %@", imageView);
    self.array = [NSMutableArray arrayWithObject:[NSData dataWithData:UIImagePNGRepresentation(imageView.image)**];

    [self.array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView2.image)**];
     [self.array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView3.image)**];
      [self.array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView4.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 = [**UIImage alloc] initWithData:[self.array objectAtIndex:0**];
        imageView2.image = [**UIImage alloc] initWithData:[self.array objectAtIndex:1**];
        imageView3.image = [**UIImage alloc] initWithData:[self.array objectAtIndex:2**];
        imageView4.image = [**UIImage alloc] initWithData:[self.array objectAtIndex:3**];



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

        backToGalleryButton.hidden = YES;
        tapToDeleteLabel.hidden = YES;
        deleteButton1.hidden = YES;
        [super viewDidLoad];

    }




///// shows the hidden and invisible "delete" button over each photo.
- (IBAction)editButtonPressed:(id)sender {
    grabButton.hidden = YES;
    editButton.hidden = YES;
    backToGalleryButton.hidden = NO;
    tapToDeleteLabel.hidden = NO;
    deleteButton1.hidden = NO;
}
////

// 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;

}

- (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);
        [self.array removeObjectAtIndex: alertView.tag];
        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"];
}


更新:我添加了断点,并发现((UIImageView *)[self.view viewWithTag:alertView.tag]).image =nil;是导致崩溃的行,我仍然无法弄清楚原因。

最佳参考


这是@MichaelDautermann的扩展,他非常清楚UIButton有一个setImage:forState:方法,但没有setImage方法。但是,您正在调用set image。不是按钮,而是当你说imageView.image和imageView2.image。这将调用图像视图的setter方法。我会设置一个断点(或使用NSLog和%@项)来确保imageView实际上是一个imageView而不是一个按钮。如果它从某种程度上改变了你,这可能导致问题。只需在这两行设置一个断点,看看你是否通过它们。


另外,如果Xcode没有弹出到实际导致问题的那一行,请检查崩溃日志。符号化,日志将为您提供行号。或者,一种不太直接的方法是在末尾设置断点。你在答案中提供的方法,看看你遇到了多少。一旦崩溃,你可以缩小导致你悲伤的方法,然后开始在方法中设置断点,直到你到达相关的行。


更新:
你在评论中说过((UIImageView *)[[self.view viewWithTag:alertView.tag]])。image=nil就是你所拥有的,但是self.view是一个UIControl。更改演员表不会影响结果.UIImageView的图像是你试图删除UIControl的子视图吗?如果没有,你永远不会从viewWithTag返回图像视图。通常,self.view指的是一个视图控制器的视图,所以如果你得到一个UIControl,我的假设是你的整个视图是一个UIControl,或者你在错误的类中做这个。你在做什么课这个,以及它的子类是什么?看起来你在视图控制器中这样做了,但我只想确定。再次,在任何一种情况下(UIControl或UIImageView),两个类都不响应setImage。

其它参考1


我没有看到setImage:在您粘贴到问题中的任何代码中被调用,但我可以告诉您:UIButtonsetImage方法实际上需要一个按钮状态作为第二个参数。


例如


[UIButton setImage: forState:] [8]


我已经为你链接了Apple的文档。


如果您对setImage:的调用没有第二个参数,那么就可以解释您所看到的无法识别的选择器错误。