add tap event on iOS

src/event.h

@@ -89,6 +89,7 @@ enum class kEventCategory : uint8_t
     KeyEvent,
     ButtonEvent,
     GestureEvent,
+    TouchEvent,
 };
 
 enum class kEventType : uint8_t
@@ -107,6 +108,7 @@ enum class kEventType : uint8_t
     GestureStart,
     GestureMove,
     GestureEnd,
+    TouchTap,
     KeyDown,
     KeyUp,
     KeyChar,
@@ -158,3 +160,12 @@ public:
     glm::vec2 m_pos;
     glm::vec2 m_pos_delta;
 };
+
+class TouchEvent : public Event
+{
+public:
+    TouchEvent() { m_cat = kEventCategory::TouchEvent; }
+    glm::vec2 m_pos;
+    int m_finger_count;
+    int m_tap_count;
+};