重新排序 CollectionView 不工作在 cdoe 后面购买添加视图

Question

我尝试添加我的 UICollectionView，但 MoveItem 不工作我的移动事件没有调用。我不确定，但我尝试在故事情节中添加它可以工作，但是当我通过在空 UIview 中添加视图来尝试在代码后面时。

这是我的 UICollectionViewDataSource

public override bool CanMoveItem(UICollectionView collectionView, NSIndexPath indexPath) {
    // We can always move items
    Console.WriteLine("Is Move");
    return true;
}
public override void MoveItem(UICollectionView collectionView, NSIndexPath sourceIndexPath, NSIndexPath destinationIndexPath) {
    // Reorder our list of items
    Console.WriteLine("Item move");
    var item = Numbers[(int) sourceIndexPath.Item];
    Numbers.RemoveAt((int) sourceIndexPath.Item);
    Numbers.Insert((int) destinationIndexPath.Item, item);
}

我的 UICollectionView class:

#region Computed Properties
public WaterfallCollectionSource Source {
    get {
        return (WaterfallCollectionSource) DataSource;
    }
}#
endregion

# region Constructors
public WaterfallCollectionView(IntPtr handle): base(handle) {}#
endregion

# region Constructors
public WaterfallCollectionView(CGRect frame, UICollectionViewLayout layout): base(frame, layout) {}#
endregion
public override void AwakeFromNib() {
    base.AwakeFromNib();

    // Initialize
    DataSource = new WaterfallCollectionSource(this);
    Delegate = new WaterfallCollectionDelegate(this);

}

我的 UIViewController

   WaterfallCollectionView Waterfall;
public ViewController(IntPtr handle): base(handle) {}

public override void ViewDidLoad() {
    base.ViewDidLoad();
    // Perform any additional setup after loading the view, typically from a nib.
    var flowLayout = new UICollectionViewFlowLayout() {
        ItemSize = new CGSize((float) UIScreen.MainScreen.Bounds.Size.Width - 20.0 f, 50.0 f),
    };
    var uICollectionView = new CGRect(0, 0, (int) UIScreen.MainScreen.Bounds.Size.Width, (int) UIScreen.MainScreen.Bounds.Size.Height);
    Waterfall = new WaterfallCollectionView(uICollectionView, flowLayout);
    Waterfall.DataSource = new WaterfallCollectionSource(Waterfall);
    Waterfall.Delegate = new WaterfallCollectionDelegate(Waterfall);
    MainView.AddSubview(Waterfall);
    var log = new UILongPressGestureRecognizer();
}

Answer 1

欢迎来到 SO！

来自共享代码，没有看到为 uICollectionView 添加 UILongPressGestureRecognizer。 MoveItem方法不能自动调用，需要UILongPressGestureRecognizer.

调用

例如，为CollectionView添加长按方法如下：

UILongPressGestureRecognizer uILongPressGesture = new UILongPressGestureRecognizer(longPressGesture);
collectionView.AddGestureRecognizer(uILongPressGesture );

那么实现的longPressGesture方法就是：

private void longPressGesture(UILongPressGestureRecognizer longPressGesture)
{
    switch (longPressGesture.State)
    {
        case UIGestureRecognizerState.Began:
            {
                Console.WriteLine("long press start");
                CGPoint touchPoint = longPressGesture.LocationInView(collectionView);
                NSIndexPath selectedIndexPath = collectionView.IndexPathForItemAtPoint(touchPoint);
                if (null != selectedIndexPath)
                {
                    collectionView.BeginInteractiveMovementForItem(selectedIndexPath);
                }
            }

            break;

        case UIGestureRecognizerState.Changed:
            {
                Console.WriteLine("long press changed");
                CGPoint touchPoint = longPressGesture.LocationInView(collectionView);
                collectionView.UpdateInteractiveMovement(touchPoint);
            }
            break;
        case UIGestureRecognizerState.Ended:
            {
                 Console.WriteLine("long press end");
                collectionView.EndInteractiveMovement();
                break;
            }

        default:
            {
                collectionView.CancelInteractiveMovement();
                break;
            }
    }
}

效果：

重新排序 CollectionView 不工作在 cdoe 后面购买添加视图

Reorder CollectionView is not working buy adding view in cdoe behind

c#

xamarin.ios