我正在开发一个行为类似于照片库的应用程序，并且我正在实现让用户从他们的画廊中删除照片的选项。为此，我决定在每张图片上放置一个隐形按钮。当用户点击“编辑”按钮时，每张图片上隐藏的删除按钮将变为活动状态。为了简单起见，我在每个隐藏按钮上使用了相同的 IBOutlet，并且我在 Interface Builder 中适当地标记了每个按钮。当用户点击图片上的按钮时，会出现一个警告视图，询问他们是否真的要删除它。如果他们单击“是”，我将调用 removeObjectAtIndex。这是我正在使用的代码：
- (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.");
[self.array removeObjectAtIndex: alertView.tag];
}
[self.user setObject:array forKey:@"images"];
}
这里的问题是，当我在警报视图中单击“是”时，什么也没有发生。但是，如果我再次点击图像并单击“是”，应用程序崩溃，并且调试状态： 由于未捕获的异常 'NSRangeException' 导致应用程序终止，原因：'-[__NSCFArray removeObjectAtIndex:]: index (0) Beyond bounds (0)'所以，我不知道从哪里开始，我对编程还是很陌生，一切对我来说都是正确的。非常感谢任何帮助，谢谢！
这是我将它们添加到数组中的方法：
////start of saving////
- (void)viewWillAppear:(BOOL)animated
{
self.user = [NSUserDefaults standardUserDefaults];
self.array = [[self.user objectForKey:@"images"]mutableCopy];
while(self.array == nil)
{
[self.user setObject:[NSMutableArray arrayWithObject:@""] forKey:@"images"];
self.array = [[self.user objectForKey:@"images"]mutableCopy];
NSLog(@"%@",@"attempting to create an array to store the images in");
}
}
- (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.array addObject:[NSData dataWithData:UIImagePNGRepresentation(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 = [[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]];
imageView5.image = [[UIImage alloc] initWithData:[self.array objectAtIndex:4]];
imageView6.image = [[UIImage alloc] initWithData:[self.array objectAtIndex:5]];
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];
}
- (void)viewDidUnload
{
self.user = nil;
}
////end of saving
///// 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;
}
- (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.");
NSLog(@"Array: %@, index: %d", self.array, alertView.tag);
[self.array removeObjectAtIndex: alertView.tag];
}
[self.user setObject:array forKey:@"images"];
}
@end
编辑：这是我用来将对象从用户相机胶卷放入 UIImageView 的代码：
- (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;
[picker dismissModalViewControllerAnimated:YES];
[self.popover dismissPopoverAnimated:YES];
return;
}
if (imageView2.image == nil) {
imageView2.image = img;
[picker dismissModalViewControllerAnimated:YES];
[self.popover dismissPopoverAnimated:YES];
return;
}
if (imageView3.image == nil) {
imageView3.image = img;
[picker dismissModalViewControllerAnimated:YES];
[self.popover dismissPopoverAnimated:YES];
return;
}
if (imageView4.image == nil) {
imageView4.image = img;
[picker dismissModalViewControllerAnimated:YES];
[self.popover dismissPopoverAnimated:YES];
return;
}
}
当我添加 NSLog(@"Array: %@, index: %d", self.array, alertView.tag); 就在 removeAtIndex 之前，控制台说2012-04-03 18:39:39.066 AppName[1631:f803] Array: (null), index: 0.这可能是原因吗？我不确定为什么会这样，我认为代码看起来不错。