ABPeoplePickerNavigationController 保存较大的图像需要很长时间
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【中文标题】ABPeoplePickerNavigationController 保存较大的图像需要很长时间【英文标题】：ABPeoplePickerNavigationController saving larger image takes a LONG time 【发布时间】：2011-09-27 02:22:29 【问题描述】：我使用 ABPeoplePickerNavigationController 将 iPhone 联系人导入我的应用程序。我最近决定，不仅保存缩略图，还保存整个图像。使用 iPad 并且可能需要具有不同裁剪的更大图像，我认为这是要走的路。但是，在导入后保存一些新联系人时，保存时间较长，具体取决于照片的大小。没有照片，保存是即时的，所以我知道这与照片的大小以及我正在用它做什么有关。相关代码如下，以防任何人指出我做错了什么......
- (BOOL)peoplePickerNavigationController: (ABPeoplePickerNavigationController *)peoplePicker shouldContinueAfterSelectingPerson:(ABRecordRef)contact
NSLog(@"%s", __FUNCTION__);
self.selectedThumbnailImage = nil;
self.selectedImage = nil;
if(ABPersonHasImageData(contact))
self.selectedThumbnailImage = nil;
NSData *imgData = (NSData *)ABPersonCopyImageData(contact);
UIImage *pickedImage = [UIImage imageWithData:imgData];
[imgData release];
self.selectedImage = pickedImage;
CGSize imageSize = pickedImage.size;
CGSize targetSize = CGSizeMake(110.0,120.0);
CGFloat width = imageSize.width;
CGFloat height = imageSize.height;
CGFloat targetWidth = targetSize.width;
CGFloat targetHeight = targetSize.height;
CGFloat scaleFactor = 0.0;
CGFloat scaledWidth = targetWidth;
CGFloat scaledHeight = targetHeight;
CGPoint thumbnailPoint = CGPointMake(0.0,0.0);
if (CGSizeEqualToSize(imageSize, targetSize) == NO)
CGFloat widthFactor = targetWidth / width;
CGFloat heightFactor = targetHeight / height;
if (widthFactor > heightFactor)
scaleFactor = widthFactor; // scale to fit height
else
scaleFactor = heightFactor; // scale to fit width
scaledWidth = width * scaleFactor;
scaledHeight = height * scaleFactor;
// center the image
if (widthFactor > heightFactor)
thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
else
if (widthFactor < heightFactor)
thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
UIGraphicsBeginImageContext(targetSize);
CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;
[pickedImage drawInRect:thumbnailRect];
self.selectedThumbnailImage = UIGraphicsGetImageFromCurrentImageContext();
[[NSNotificationCenter defaultCenter] postNotificationName:@"personChanged" object:nil];
UIGraphicsEndImageContext();
self.nameFirstString = (NSString *)ABRecordCopyValue(contact, kABPersonFirstNameProperty);
self.nameLastString = (NSString *)ABRecordCopyValue(contact, kABPersonLastNameProperty);
[nameFirstTextField setText:nameFirstString];
[nameLastTextField setText:nameLastString];
self.person.birthday = (NSDate *)ABRecordCopyValue(contact, kABPersonBirthdayProperty);
[self updateRightBarButtonItemState];
[self dismissModalViewControllerAnimated:YES];
return NO;
- (BOOL)peoplePickerNavigationController:(ABPeoplePickerNavigationController *)peoplePicker shouldContinueAfterSelectingPerson:(ABRecordRef)person property:(ABPropertyID)property identifier:(ABMultiValueIdentifier)identifier
NSLog(@"%s", __FUNCTION__);
return NO;
- (void)saveImage
// Delete any existing image.
NSManagedObjectContext *context = [[UIApplication sharedDelegate] managedObjectContext];
Image *oldImage = person.image;
if (oldImage != nil)
[context deleteObject:(NSManagedObject*)oldImage];
// Create an image object for the new image.
UIImage *newImage = [NSEntityDescription insertNewObjectForEntityForName:@"Image" inManagedObjectContext:context];
[newImage setValue:selectedImage forKey:@"image"];
[self.person setValue:newImage forKey:@"image"];
- (IBAction)save:(id)sender
NSLog(@"%s", __FUNCTION__);
[self.person setValue:selectedThumbnailImage forKey:@"thumbnailImage"];
[self saveImage];
self.person.nameFirst = nameFirstString;
self.person.nameLast = nameLastString;
NSError *error;
NSManagedObjectContext *context = [[UIApplication sharedDelegate] managedObjectContext];
if (![context save:&error])
NSLog(@"AddPersonViewController - addViewControllerDidFinishWithSave - Person MOC save error %@, %@", error, [error userInfo]);
exit(-1); // Fail
[self.delegate addPersonViewController:self didFinishWithSave:YES didEditPerson:person];
编辑：我将 saveImage 代码更改为以下代码并收到错误“非法尝试在不同上下文中的对象之间建立关系‘人’”：
- (void)saveImage
// Delete any existing image.
//NSManagedObjectContext *context = [[UIApplication sharedDelegate] managedObjectContext];
NSLog(@"%s", __FUNCTION__);
NSManagedObjectContext *savingPhotoContext = [[NSManagedObjectContext alloc] init];
self.savingPhotoMOC = savingPhotoContext;
[savingPhotoMOC setPersistentStoreCoordinator:[[[UIApplication sharedDelegate] managedObjectContext] persistentStoreCoordinator]];
[savingPhotoContext release];
Image *oldImage = person.image;
if (oldImage != nil)
[savingPhotoMOC deleteObject:(NSManagedObject*)oldImage];
// Create an image object for the new image.
UIImage *newImage = [NSEntityDescription insertNewObjectForEntityForName:@"Image" inManagedObjectContext:savingPhotoMOC];
[newImage setValue:selectedImage forKey:@"image"];
[newImage setValue:self.person forKey:@"person"];
//[self.person setValue:newImage forKey:@"image"];
NSNotificationCenter *dnc = [NSNotificationCenter defaultCenter];
[dnc addObserver:self selector:@selector(addControllerContextDidSave:) name:NSManagedObjectContextDidSaveNotification object:savingPhotoMOC];
NSError *error;
if (![savingPhotoMOC save:&error])
NSLog(@"Occasion View Controller - addViewControllerDidFinishWithSave - Adding MOC save error %@, %@", error, [error userInfo]);
exit(-1); // Fail
[dnc removeObserver:self name:NSManagedObjectContextDidSaveNotification object:savingPhotoMOC];
self.savingPhotoMOC = nil;
- (void)addControllerContextDidSave:(NSNotification*)saveNotification
NSLog(@"%s", __FUNCTION__);
NSManagedObjectContext *context = [[UIApplication sharedDelegate] managedObjectContext];
[context mergeChangesFromContextDidSaveNotification:saveNotification];
【问题讨论】：
如果需要很长时间，您应该在后台执行此操作，并使用委托回调或 nsnotification 通知其他可能在保存完成时使用它的函数。 OK.. 我想这将涉及使用单独的 managedObjectContext？为了简化事情，我只为我的整个应用程序使用一个 MOC。我确信这是一个坏主意，但它与所有上下文都变得有点太混乱了。我真的没有看到需要多个上下文，但现在我想我知道了。谢谢。 嗯，好吧，现在显示我的经验不足，但我发现我无法在一个上下文中保存新对象“人”，同时保存对象“图像”（并将其分配给“人” ) 在另一种情况下。我认为如果我在新上下文中合并这将起作用，但是：“非法尝试在不同上下文中的对象之间建立关系'人'”..不知道从这里去哪里.. 也许有人可以指点我一个关于简单线程的好教程？ 您可以使用 GCD 或 nsoperationqueue...对于 gcd，请查看“火热机器人”的博客。我喜欢它，因为他解释的不仅仅是复制粘贴的代码。 【参考方案1】：如果需要很长时间，您应该在后台执行此操作，并使用委托回调或 nsnotification 在保存完成时通知可能正在使用它的其他函数。您可以使用 GCD 或 nsoperationqueue ...对于 gcd，请查看“火热机器人”的博客。我喜欢它，因为他解释的不仅仅是复制粘贴的代码。
【讨论】：
我将把它设置为答案，因为我知道它是正确的。但是，我个人很难让它工作并且还没有（见this link）。希望尽快让它工作。感谢您指出正确的方向。以上是关于ABPeoplePickerNavigationController 保存较大的图像需要很长时间的主要内容，如果未能解决你的问题，请参考以下文章