Question

我正在使用NSURLRequest加载对象的详细信息。此对象具有“正在加载”的属性。在ViewController中显示对象的详细信息，该对象有一个观察者，用于＆＃39; isLoading＆＃39;。

此观察员将在“loadFromResultList＆＃39; （在＆＃39; viewWillAppear＆＃39;中调用）并且它将在＃observe****VerueForKeyPath＆＃39;中注销。或者在＆＃39; viewWillDisappear＆＃39; （如有必要）。

有时，应用程序因“无理由”而崩溃。（例外类型SIGSEGV）。所以这意味着观察者消息被发送到一个解除分配的对象。

我尝试使用启用的NSZombies。但这种崩溃有时只会发生。所以我无法真正跟踪它。

以下是代码：

// ViewController
- (void)viewWillAppear:(BOOL)animated {
    if (self.advertisement == nil) 
    {
        [self loadAdFromResultList];
    }
}

- (void)loadAdFromResultList {
    self.advertisement = [appDelegate.currentSearch.result objectAtIndex:self.currentAdIndex];

    if ([self.advertisement isKindOfClass:[NSError class]]) {
    } else {
        [self.advertisement addObserver:self forKeyPath:@"isLoading" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:NULL];
         @try {
             [self.advertisement load];
         } @catch […]
     }
}

// Advertisment Object class
- (void)load {
        self.isLoading = true;
        [api beginGetAdvertisement:guid target:self selector:@selector(beginGetAdvertisementCallback:) userState:self];
}

// ViewController
- (void)beginGetAdvertisementCallback:(FEURLAsyncResult*)result {
    […]
    [api endGetAdvertisement:result];

    self.isLoading = false;
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
    if ([keyPath isEqualToString:@"isLoading"]) {
        @try {
            // Remove observer
            [self.advertisement removeObserver:self forKeyPath:@"isLoading"];
        }
        @catch (NSException *exception) {
            NSLog(@"[x] %s: %@", __PRETTY_FUNCTION__, exception);
        }
    }
}

- (void)viewWillDisappear:(BOOL)animated {
    @try {
        [self.advertisement removeObserver:self forKeyPath:@"isLoading"];
    }
    @catch (NSException *exception) {
        NSLog(@"err: %@", exception);
    }
    [super viewWillDisappear:animated];
}

这是Stacktrace：

    Thread 0 Crashed:
1    libobjc.A.dylib     _objc_msgSend + 6
2    Foundation  NSKeyValuePushPendingNotificationPerThread + 215
3    Foundation  NSKeyValueWillChange + 475
4    Foundation  -[NSObject(NSKeyValueObserverNotification) willChangeValueForKey:] + 181
5    Foundation  _NSSetCharValueAndNotify + 77
6    Fewo    -[FEAdvertisement load] + 381
7    Fewo    -[FEExposeViewController loadAdFromResultList] (FEExposeViewController.m:1145)
8    Fewo    -[FEExposeViewController viewWillAppear:] (FEExposeViewController.m:122)
9    UIKit   -[UIViewController _setViewAppearState:isAnimating:] + 347
…
14   Fewo    -[FEResultListViewController tableView:didSelectRowAtIndexPath:] (FEResultListViewController.m:358)
15   UIKit   -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] + 1079
…
26   Fewo    main (main.m:17)

任何可能导致此次崩溃的想法都欢迎。

Thx to all

iPhone KVO崩溃（SIGSEGV）

0 个答案: