c# - Ways to detect 2D collision other than OnCollisionEnter2D

Question

This might come off as a stupid question, but in an if statement, is it possible to check if the object is currently colliding with another object?

Here is what I had thought of initially (in the code snipit bellow) but for some odd reason that I can't figure out, the variable onFloor is sometimes false when the object is being pushed upwards by the Platform.

void OnCollisionEnter2D(Collision2D c)
{
    switch(c.gameObject.tag)
    {
        case "Platform":
            onFloor = true;
            break;
        default:
            break;
    }
}

void OnCollisionExit2D(Collision2D c)
{
    switch(c.gameObject.tag)
    {
        case "Platform":
            onFloor = false;
            break;
        default:
            break;
    }
}

And for that reason, I am asking if there are any ways to detect if the circle collider of said object is colliding with box collider of intersecting object while in code. something like

if(CircleCollider2D.CollidingObject != null && CircleCollider2D.CollidingObject.tag == "Platform")
{ /*Code I'd like to do here*/ }

Now that's only my imagination trying to think of some way of it that could work but you get the point.

So, I ask, are there any solutions for my imagination?

After discussing with Programmer, IsTouching is underlined and giving the error: 'Collider2D' does not contain a definition for 'IsTouching' and no extension method 'IsTouching' accepting a first argument of type 'Collider2D' could be found (are you missing a using directive or an assembly reference?).

Here is the slimmed down code:

using UnityEngine;

public class Ball : MonoBehaviour
{ 
    Vector2 jumpVelocity;
    public Collision2D platform;

    // Use this for initialization
    void Start()
    {
        jumpVelocity = new Vector2(0, rigidbody2D.gravityScale * 100);
    }

    void FixedUpdate()
    {
        if (Input.GetKey(KeyCode.Space) && collider2D.IsTouching(platform))
        {
            rigidbody2D.AddForce(jumpVelocity, ForceMode2D.Force);
        }
    }
}

note that even changing collider2D to a Collision2D variable and taking that variable.collider.IsTouching results the same error.

Answer 1

Are there different solutions than OnCollisionEnter2D

Yes. Many of them!

CircleCollider2D, other 2D colliders and its base class Collision2D, have built in functions to do this.

public bool IsTouching(Collider2D collider); //Check collision by the provided collider
public bool IsTouchingLayers(); //Check collision by any collision
public bool IsTouchingLayers(int layerMask); //Check collision by layer
public bool OverlapPoint(Vector2 point); //Check collision by position

The first function is more appropriate for this.

Simple Example:

Collision2D collider1;
Collision2D collider2;

void Update()
{
    //Checks if collider1 is touching with collider2
    if (collider1.collider.IsTouching(collider2.collider))
    {

    }
}

Example with the OnCollisionEnter2D function:

public CircleCollider2D myCircleCollider;

void OnCollisionEnter2D(Collision2D c)
{
    if (c.collider.IsTouching(myCircleCollider))
    {

    }
}