Wired behaviour on while exit condition inside coroutine

Hi guys,
I have this wired problem. I have this code:

Code (CSharp):

1.         do {
2.  
3.             Debug.Log ("Actual postion: " + transform.position + "End position " + this.endJumpPos);
4.             float distCovered = (Time.time - startJumpTime) * this.jumpSpeed;
5.             //Converted the distance in franction
6.             float distCoveredInFraction = distCovered / this.verticalJumpDistance;
7.             transform.position = Vector2.Lerp(this.initialJumpPos, this.endJumpPos ,distCoveredInFraction);
8.             yield return null;
9.         } while (transform.position.y < this.endJumpPos.y);

This code works very well on the unity editor, but it doesn't work on iOS device because the while exit condition it's not triggered. I found a workaround to solve this problem by change the previous code into this:

Code (CSharp):

1. bool endJump = false;
2.         do {
3.             float distCovered = (Time.time - startJumpTime) * this.jumpSpeed;
4.             //Converted the distance in franction
5.             float distCoveredInFraction = distCovered / this.verticalJumpDistance;
6.             transform.position = Vector2.Lerp(this.initialJumpPos, this.endJumpPos ,distCoveredInFraction);
7.             if (!(transform.position.y < this.endJumpPos.y)) {
8.                 endJump = true;
9.             }
10.             Debug.Log ("Actual postion: " + transform.position + "End position " + this.endJumpPos);
11.             yield return null;
12.         } while (!endJump);

This code works very well also on iOS, so my question is very simple. I want to understand why the while condition it's not triggered in iOS device?