collectionView performBatchUpdates会警告快照未渲染的视图，导致快照为空

Question

我正在调用performBatchUpdates来插入和删除collectionview中的单元格。

但是当我这样做时会发出警告。这是我的代码。

-(void)updateActiveuser:(NSMutableArray *)arrActiveUser{

[self.collectionView performBatchUpdates:^{
    NSMutableArray *addIndexPath = [NSMutableArray array];
    NSMutableArray *removeIndexPath = [NSMutableArray array];
    NSMutableArray *arrOffline = [[NSMutableArray alloc] init];
    for (User *offlLineuser in self.arrOnlineUsers) {
        User *userExist = [self getActiveUserWithUserId:offlLineuser.userID forArray:arrActiveUser];
        if (userExist == nil) {
            [removeIndexPath addObject:[NSIndexPath indexPathForRow:[self.arrOnlineUsers indexOfObject:offlLineuser] inSection:0]];
            [arrOffline addObject:offlLineuser];
        }

    }
    [self.arrOnlineUsers removeObjectsInArray:arrOffline];
    NSInteger count = 0;
    for (User *obj in arrActiveUser) 
    {
        User *userExist = [self getActiveUserWithUserId:obj.userID forArray:self.arrOnlineUsers];
        if (userExist == nil) {

            [addIndexPath addObject:[NSIndexPath indexPathForRow:count inSection:0]];
            [self.arrOnlineUsers addObject:obj];
            count = count +1;
        }

    }

    [self.collectionView insertItemsAtIndexPaths:addIndexPath];
    [self.collectionView deleteItemsAtIndexPaths:removeIndexPath];

} completion:^(BOOL finished) {
    [self.collectionView reloadData];
}];

}

我正在主线程中调用上述方法。

  

快照未呈现的视图将导致快照为空。确保在快照之前或屏幕更新后快照中至少渲染过一次视图。