Iphone NSKeyedArchiver被调用两次

当我在iphone应用程序关闭时看着控制台时，我的encodewithcoder似乎被调用了两次。即使我只对一组“新闻项”编码一次

这正常吗

(void)encodeWithCoder:(NSCoder *)encoder {
    NSLog(@"News encode called %@", self.title);    

    [encoder encodeObject:self.newsItemId forKey:KNewsItemNewsIdKey];   
    [encoder encodeObject:self.title forKey:KNewsItemTitleKey];
    [encoder encodeObject:self.author forKey:KNewsItemAuthorKey];
    [encoder encodeObject:self.description forKey:KNewsItemDescriptionKey];
    [encoder encodeObject:self.imageUrl forKey:KNewsItemImageUrlKey];
    [encoder encodeObject:self.thumbnailUrl forKey:KNewsItemThumbnailUrlKey];
    [encoder encodeObject:self.createdAt forKey:KNewsItemCreatedAtKey];

    //Images
    //convert from PNG to NSData, other method available for JPG
    NSData *savedImageData = UIImagePNGRepresentation(self.savedImage); 
    [encoder encodeObject:savedImageData forKey:KNewsItemSavedImageKey];

    NSData *thumbnailImageData = UIImagePNGRepresentation(self.savedThumbnail); 
    [encoder encodeObject:thumbnailImageData forKey:KNewsItemSavedThumbnailKey];

}


//code to encode
    [archiver encodeObject:self.newsArray forKey:KNewsArrayDataKey];

在NSLog语句上设置一个断点，并检查堆栈跟踪以查看每次谁在呼叫您