import from UniRx and some modified.

Assets/UniRx.Async/Triggers/AsyncCollision2DTrigger.cs

@@ -0,0 +1,69 @@
+
+#if CSHARP_7_OR_LATER || (UNITY_2018_3_OR_NEWER && (NET_STANDARD_2_0 || NET_4_6))
+#pragma warning disable CS1591 // Missing XML comment for publicly visible type or member
+
+using System.Collections.Generic;
+using System.Threading;
+using UnityEngine;
+using UnityEngine.EventSystems;
+
+namespace UniRx.Async.Triggers
+{
+    [DisallowMultipleComponent]
+    public class AsyncCollision2DTrigger : AsyncTriggerBase
+    {
+        AsyncTriggerPromise<Collision2D> onCollisionEnter2D;
+        AsyncTriggerPromiseDictionary<Collision2D> onCollisionEnter2Ds;
+        AsyncTriggerPromise<Collision2D> onCollisionExit2D;
+        AsyncTriggerPromiseDictionary<Collision2D> onCollisionExit2Ds;
+        AsyncTriggerPromise<Collision2D> onCollisionStay2D;
+        AsyncTriggerPromiseDictionary<Collision2D> onCollisionStay2Ds;
+
+
+        protected override IEnumerable<ICancelablePromise> GetPromises()
+        {
+            return Concat(onCollisionEnter2D, onCollisionEnter2Ds, onCollisionExit2D, onCollisionExit2Ds, onCollisionStay2D, onCollisionStay2Ds);
+        }
+
+
+        void OnCollisionEnter2D(Collision2D coll)
+        {
+            TrySetResult(onCollisionEnter2D, onCollisionEnter2Ds, coll);
+        }
+
+
+        public UniTask OnCollisionEnter2DAsync(CancellationToken cancellationToken = default(CancellationToken))
+        {
+            return GetOrAddPromise(ref onCollisionEnter2D, ref onCollisionEnter2Ds, cancellationToken);
+        }
+
+
+        void OnCollisionExit2D(Collision2D coll)
+        {
+            TrySetResult(onCollisionExit2D, onCollisionExit2Ds, coll);
+        }
+
+
+        public UniTask OnCollisionExit2DAsync(CancellationToken cancellationToken = default(CancellationToken))
+        {
+            return GetOrAddPromise(ref onCollisionExit2D, ref onCollisionExit2Ds, cancellationToken);
+        }
+
+
+        void OnCollisionStay2D(Collision2D coll)
+        {
+            TrySetResult(onCollisionStay2D, onCollisionStay2Ds, coll);
+        }
+
+
+        public UniTask OnCollisionStay2DAsync(CancellationToken cancellationToken = default(CancellationToken))
+        {
+            return GetOrAddPromise(ref onCollisionStay2D, ref onCollisionStay2Ds, cancellationToken);
+        }
+
+
+    }
+}
+
+#endif
+