Ios 了解通知和更新属性

我有一个拍照应用程序，它有一个PhotoViewController，代码如下，用于通知。此视图控制器上还有一个按钮，用于启动拍照视图控制器，该控制器以模式打开，并通过委派显示在PhotoViewController中

PhotoViewVC.h包含：

@interface PhotoViewVC : UIViewController <UITextViewDelegate, PhotoTakingVCDelegate>

// Photo data
@property (nonatomic, strong) NSData *photoData;
@property (nonatomic, strong) NSString *photoText;
@property (nonatomic, strong) NSString *photoObject;
@property (nonatomic, strong) NSString *photoParentObject;
@property (nonatomic, strong) NSString *photoUsername;
@property (nonatomic, strong) NSNumber *photoBestCount;
@property (nonatomic, strong) NSNumber *photoReplyCount;
@property (nonatomic, strong) NSMutableAttributedString *photoLabel;
@property (nonatomic, assign) BOOL photoViewerAddedBests;

@end

我很难使我的计数增加。所以我的应用程序是这样工作的：

PhotoTakingVC启动并创建所有最佳计数（初始值为0）

PhotoViewVC已正确加载，最佳计数为0

用户在PhotoViewVC上并单击回复按钮

PhotoTakingVC弹出并拍照

PhotoViewVC为新照片创建自身的新实例

用户点击PhotoViewVC第二个实例上的“后退”按钮，返回第一个实例

最佳计数设置为1，这是正确的

在PhotoViewVC的第一个实例上再次点击回复

再次弹出PhotoTakingVC并保存照片及其数据

PhotoViewVC通过委派创建另一个PhotoViewVC实例（第三个）

用户点击第三个实例返回第一个实例

最佳计数仍然是1，应该是2

为什么_photoBestCount每次从0开始，而不是持续增加？

在步骤10中，您陈述：

PhotoViewVC通过委派创建另一个PhotoViewVC实例（第三个）

---

每次创建新VC时，您都在创建一个新的iVar

\u photoBestCount

，初始化为零。因此，如果您想要一个持久计数器，只需将该属性放入一个模型类中（称之为PhotoCounter，或其他任何名称）。创建此类的实例并将其传递到PhotoViewVC。现在，每次更新此iVar时，您都使用相同的计数器，而不是新的计数器

您是否可以更新您的帖子，添加相关iVar的定义，如

\u photoBestCount

？立即更新一秒钟，以便创建一个具有计数属性的新视图控制器？“将其传递到PhotoViewVC”是什么意思？不，创建一个具有计数属性的新类。那是你的模型对象。现在，在调用PhotoViewVC（在实例化PhotoViewVC的VC内部）之前创建这个类的一个实例，并将这个对象传递给PhotoViewVC（使用PhotoCounter类型的属性），但是PhotoViewVC有时会被自己调用，您可以传递给这个新的PhotoViewVC self.myPhotoCounter。它只是一个指针，您正在传递给这个新的PhotoViewVC实例。但是会在内存中保留你的计数器这对10台PhotoViewVCs有效吗？他们可能都有不同的最佳答案，根据哪一个被点击回复

- (void) viewDidLoad
{
    [self postNotification];
    [self listenToNotifications];
}

- (void) postNotification
{        
    NSDictionary *dataDict = [NSDictionary dictionaryWithObject:_photoObject forKey:@"photoObject"];

    [[NSNotificationCenter defaultCenter] postNotificationName:@"replyHappened" object:self userInfo:dataDict];
}

- (void) listenToNotifications
{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleReplied:) name:@"replyHappened" object:nil];
}

- (void) handleReplied:(NSNotification *) note
{
    NSDictionary *data = [note userInfo];

    if (data != nil)
    {
        NSString *object = [data objectForKey:@"photoObject"];

        // Update counts
        int count = [_photoBestCount intValue];

        count = count + 1;

        _photoBestCount = [NSNumber numberWithInt:count];

        _bestsCount.text = [NSString stringWithFormat:@"%@", _photoBestCount];
    }
}

- (void) dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

// Now the PhotoTakingVC delegation functions:

- (void) photoTakingVCDismiss:(PostViewController *) sender
{
    [sender dismissViewControllerAnimated:YES completion:nil];
}

- (void) photoTakingVCPresent:(PostViewController *) sender
{
    [self dismissViewControllerAnimated:YES completion:nil];

    PhotoViewVC *best = [[PhotoViewVC alloc] init];

    best.photoData = _photoData;
    best.photoText = _photoText;
    best.photoObject = _photoObject;
    best.photoParentObject = _photoParentObject;
    best.photoUsername = _photoUsername;
    best.photoBestCount = _photoBestCount;
    best.photoReplyCount = _photoReplyCount;
    best.photoLabel = _photoLabel;
    best.photoViewerAddedBests = _photoViewerAddedBests;

    best.hidesBottomBarWhenPushed = YES;

    [self.navigationController pushViewController:best animated:NO];
}

- (void) photoView:(NSData *) photo andText:(NSString *) text andObject:(NSString *) object andParentObject:(NSString *) parentObject andUsername:(NSString *) username andBestCount:(NSNumber *) bestCount andReplyCount:(NSNumber *) replyCount andLabel:(NSMutableAttributedString *) label andAddedBests:(BOOL) addedBests
{
    _photoData = photo;
    _photoText = text;
    _photoObject = object;
    _photoParentObject = parentObject;
    _photoUsername = username;
    _photoBestCount = bestCount;
    _photoReplyCount = replyCount;
    _photoLabel = label;
    _photoViewerAddedBests = addedBests;
}