Question

我现在有一个从故事板创建的CollectionView。如果我从模拟器运行应用程序一切正常。如果我在Device上运行相同的应用程序，则永远不会调用Get单元格方法，并且单元格永远不会出现。

这是我在ViewController中的collectionView

//Current MonthyBox CollectionView Settings 
                CurrentMonthlyBoxCollectionView.PagingEnabled = true;
                CurrentMonthlyBoxCollectionView.BackgroundColor = UIColor.Clear;
                CurrentMonthlyBoxCollectionView.SetCollectionViewLayout(new UICollectionViewFlowLayout(), true);
                ((UICollectionViewFlowLayout)CurrentMonthlyBoxCollectionView.CollectionViewLayout).ScrollDirection = UICollectionViewScrollDirection.Horizontal;
                ((UICollectionViewFlowLayout)CurrentMonthlyBoxCollectionView.CollectionViewLayout).MinimumInteritemSpacing = 10000.0f;
                CurrentMonthlyBoxCollectionView.Source = new CurrentMonthlyBoxCollectionViewSource(Vm);

这是我的收集查看来源

class CurrentMonthlyBoxCollectionViewSource : UICollectionViewSource
    {
        List<MonthlyBoxModel> CurrentBoxList;
        DashboardViewModel DashboardModel;
        public CurrentMonthlyBoxCollectionViewSource(List<MonthlyBoxModel> CurrentBoxList)
        {
            this.CurrentBoxList = CurrentBoxList;
        }
        public CurrentMonthlyBoxCollectionViewSource(DashboardViewModel model)
        {
            this.DashboardModel = model;
        }

        public override nint NumberOfSections(UICollectionView collectionView)
        {
            return 1;
        }
        public override nint GetItemsCount(UICollectionView collectionView, nint section)
        {
            return 1;
        }
        public override void ItemSelected(UICollectionView collectionView, NSIndexPath indexPath)
        {
            DashboardModel.NavigateToNextPage(DashboardModel.Model);
        }
        public override UICollectionViewCell GetCell(UICollectionView collectionView, NSIndexPath indexPath)
        {
            //Create a new cell 
            CurrentMonthlyBoxCollectionViewCell cell = (CurrentMonthlyBoxCollectionViewCell)collectionView.DequeueReusableCell("CurrentMonthlyBoxCollectionViewCell", indexPath);
            cell.setValuesForCurrentCell(DashboardModel);
            return cell;
        }
        [Export("collectionView:layout:sizeForItemAtIndexPath:")]
        public virtual SizeF SizeForItemAtIndexPath(UICollectionView collectionView, UICollectionViewLayout layout, NSIndexPath indexPath)
        {
            return new SizeF((float)collectionView.Frame.Width, 100f);
        }
    }
}

我不知道出了什么问题

更新：

根据xamarin文件＆＃34;代表＆＃34;和＆＃34;数据源＆＃34;两者都使用＆＃34; source＆＃34; 但是，当我们使用流布局并选择为集合视图单元格选择自定义大小时。我们必须从UICollectionViewFlowLayout继承并从UICollectionViewFlowLayout句柄设置委托给类所有委托相关代码到该类。

简而言之，我的集合视图代码如下所示

CurrentMonthlyBoxCollectionView.PagingEnabled = true;
                CurrentMonthlyBoxCollectionView.BackgroundColor = UIColor.Clear;
                CurrentMonthlyBoxCollectionView.SetCollectionViewLayout(new UICollectionViewFlowLayout(), true);
                ((UICollectionViewFlowLayout)CurrentMonthlyBoxCollectionView.CollectionViewLayout).ScrollDirection = UICollectionViewScrollDirection.Horizontal;
                ((UICollectionViewFlowLayout)CurrentMonthlyBoxCollectionView.CollectionViewLayout).MinimumInteritemSpacing = 10000.0f;
                CurrentMonthlyBoxCollectionView.Source = new CurrentMonthlyBoxCollectionViewSource(Vm);
                **CurrentMonthlyBoxCollectionView.Delegate = new CurrentMonthlyBoxCollectionViewDelegate(Vm);**

我添加了新课程

internal class CurrentMonthlyBoxCollectionViewDelegate : UICollectionViewDelegateFlowLayout
    {
        DashboardViewModel DashboardModel;
        public CurrentMonthlyBoxCollectionViewDelegate(DashboardViewModel DashboardModel)
        {
            this.DashboardModel = DashboardModel;
        }
        public override CGSize GetSizeForItem(UICollectionView collectionView, UICollectionViewLayout layout, NSIndexPath indexPath)
        {
            return new CGSize((float)(collectionView.Frame.Width), (float)(collectionView.Frame.Height));
        }
        public override void ItemSelected(UICollectionView collectionView, NSIndexPath indexPath)
        {
            DashboardModel.NavigateToNextPage(DashboardModel.Model);
        }
    }

这足以解决问题，并且不要忘记从collectionViewSource

中删除以下方法

[Export("collectionView:layout:sizeForItemAtIndexPath:")]
            public virtual SizeF SizeForItemAtIndexPath(UICollectionView collectionView, UICollectionViewLayout layout, NSIndexPath indexPath)
            {
                return new SizeF((float)collectionView.Frame.Width, 100f);
            }

GetCell没有被设备调用。但在模拟器上工作正常

0 个答案: