NSUserDefaults以随机方式从数组返回自定义对象

Question

当我在NSUserDefaults中保存产品数组（这是一个自定义对象），并从NSUserDefaults检索数组时，它会返回随机数组。当我检查返回的数组是否包含添加的产品时，它总是失败。这是我的代码：

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSData *data = [defaults objectForKey:@"MY_FAV_PROD"];
NSArray *myFavArray = [NSKeyedUnarchiver unarchiveObjectWithData:data];

NSMutableArray *array = [[NSMutableArray alloc] initWithArray:myFavArray];

if(myFavArray.count || array.count) {

        if([array containsObject:self.product]) {

            [array removeObject:self.product];

            myFavArray = nil;
            myFavArray = [myFavArray copy];

            data = [NSKeyedArchiver archivedDataWithRootObject:myFavArray];
            [defaults setObject:data forKey:@"MY_FAV_PROD"];
            [defaults synchronize];
            [self addButton:@"UnFilled"];

        }
        else {

            [array addObject:self.product];
            myFavArray = nil;
            myFavArray = [array copy];
            data = [NSKeyedArchiver archivedDataWithRootObject:myFavArray];
            [defaults setObject:data forKey:@"MY_FAV_PROD"];
            [defaults synchronize];
            [self addButton:@"Filled"];

        }
}
else {

    NSArray *firstObj = [[NSArray alloc] initWithObjects:self.product, nil];
     data = [NSKeyedArchiver archivedDataWithRootObject:firstObj];
    [defaults setObject:data forKey:@"MY_FAV_PROD"];
    [defaults synchronize];
    [self addButton:@"Filled"];

}

data = [defaults objectForKey:@"MY_FAV_PROD"];
myFavArray = [NSKeyedUnarchiver unarchiveObjectWithData:data];
NSLog(@"%@",myFavArray);

请帮忙