【Unity】UniRxを使ったドラッグ移動のサンプル【UniRx】 ref: http://qiita.com/su10/items/ae3fd460a5762438a9d1

Drag.cs

using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;
using UniRx;
using UniRx.Triggers;

public class Drag : MonoBehaviour
{
    public RectTransform target;
    public bool horizontal = true;
    public bool vertical = true;

    public bool interactable {
        get { return this.graphic.raycastTarget; }
        set { this.graphic.raycastTarget = value; }
    }

    private Canvas _canvas;

    public Canvas canvas {
        get {
            if (_canvas == null) {
                _canvas = this.GetComponentInParent<Canvas>();
            }
            return _canvas;
        }
        set { _canvas = value; }
    }

    private Graphic _graphic;

    private Graphic graphic {
        get { return _graphic ?? (_graphic = this.GetComponent<Graphic>()); }
    }

    private ObservableEventTrigger _trigger;

    private ObservableEventTrigger trigger {
        get { return _trigger ?? (_trigger = this.gameObject.GetOrAddComponent<ObservableEventTrigger>()); }
    }

    void Awake()
    {
        if (this.graphic == null) {
            Debug.LogWarning("Graphic component is required.");
            this.gameObject.AddComponent<Image>().color = Color.clear;
        }

        if (this.target == null) {
            this.target = this.GetComponent<RectTransform>();
        }

        this.trigger
            .OnBeginDragAsObservable()
            .Where(e => this.interactable && this.target)
            .SelectMany(this.trigger.OnDragAsObservable())
            .TakeUntil(this.trigger.OnEndDragAsObservable())
            .TakeWhile(e => this.interactable && this.target)
            .Select(e => GetPosition(e))
            .Pairwise() // NOTE: Buffer(2,1)だと最後にペアでない値が来る
            .RepeatUntilDestroy(this)
            .Subscribe(OnDrag)
            .AddTo(this);
    }

    private Vector3 GetPosition(PointerEventData eventData)
    {
        var screenPosition = eventData.position;
        var result = Vector3.zero;

        switch (this.canvas.renderMode) {
        case RenderMode.ScreenSpaceOverlay:
        case RenderMode.ScreenSpaceCamera:
            RectTransformUtility.ScreenPointToWorldPointInRectangle(
                this.target,
                screenPosition,
                eventData.pressEventCamera,
                out result);
            break;
        case RenderMode.WorldSpace:
            // TODO: WorldSpaceのCanvas対応
            Debug.LogWarning("not supported RenderMode.WorldSpace.");
            break;
        }

        return result;
    }

    private void OnDrag(Pair<Vector3> positions)
    {
        var deltaX = this.horizontal ? positions.Current.x - positions.Previous.x : 0;
        var deltaY = this.vertical ? positions.Current.y - positions.Previous.y : 0;
        this.target.position += new Vector3(deltaX, deltaY, 0);
    }
}