Is this the right way to do Double jumping? C#

I have tried to make a double jumping feature in my game, but it wont work. My game is on a spherical world and here is my code:

if (Input.GetButtonDown ("Jump") && grounded && jumpCount < 2){ { rigidbody.AddForce(transform.up * jumpForce); jumpCount = jumpCount + 1; } }

     if (grounded = true) {

         jumpCount = jumpCount - jumpCount;
     }


     grounded = false;
     Ray ray = new Ray (transform.position, -transform.up);
     RaycastHit hit;

     if (Physics.Raycast (ray, out hit, 1 + 0.1f,  groundedMask)) 
     {
         grounded = true;
     }
 }

Can someone fix my code, or inform me in what i am doing wrong so i can fix it, i am a beginner at Unity. Thanks :D