ABPeoplePickerNavigationController保存較大的圖像需要很長時間

Question

我使用ABPeoplePickerNavigationController將iPhone聯系人導入到我的應用程序中。 我最近決定，不僅要保存縮略圖，還要保存整個圖像。 使用iPad並可能需要較大的圖像並進行不同的裁剪，我認為這是要走的路。 但是，在導入后保存一些新的聯系人時，保存時間較長，具體取決於照片的大小。 沒有照片，並且保存是立即進行的，因此我知道這與照片的大小以及我在處理照片有關。 相關代碼在下面，以防有人指出我做錯了什么...

    - (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];
}

編輯：我將saveImage代碼更改為以下代碼，並得到錯誤“非法嘗試在不同上下文中的對象之間建立關系“人”的錯誤”：

- (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];  

}

Answer 1

如果需要很長時間，則應在后台執行此操作，並在保存完成后使用委托回調或nsnotification通知可能正在使用它的其他函數。 您可以使用GCD或nsoperationqueue ...有關gcd的信息，請訪問“火熱的機器人”博客。 我喜歡它，因為他解釋的不僅是提供復制粘貼的代碼。