Iphone 我在大头针上加了一个观察者。有一个问题：有时我会得到双重调用observeValueForKeyPath

我在大头针上加了一个观察者。有一个问题：当我点击一个pin时，有时我会得到双重调用observeValueForKeyPath。我需要做什么

annotationView.enabled = YES;
annotationView.animatesDrop = YES;
annotationView.pinColor = MKPinAnnotationColorRed,
annotationView.canShowCallout = YES;

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    NSString *action = (NSString*)context;

if([action isEqualToString:@"ANSELECTED"])
{
    BOOL annotationAppeared = [[change valueForKey:@"new"] boolValue];
    MKAnnotationView *annotationView = (MKAnnotationView *)object;
    if ( [annotationView.annotation isKindOfClass:[RestaurantLocation class]] )
    {
        RestaurantLocation *annot = (RestaurantLocation *)annotationView.annotation;
        if (annotationAppeared) 
        {do something}}

}

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您正在观察哪个关键路径？为什么不使用didSelectAnnotationView委托方法？