Change hand IK over time instead of it just snapping to 0 and 1 - unity3d

Question

I'm trying to get my characters rig to go from hand IK 0 to 1 over a period of time instead of just snapping to it. How could I go about doing that?
public TwoBoneIKConstraint rightHandIK; //on animator manager script // getting hand IK from inspector so can change weight
public TwoBoneIKConstraint leftHandIK; //on animator manager script
if (animatorManager.isAimingGunn)
{
animatorManager.leftHandIK.weight = 1;
animatorManager.rightHandIK.weight = 1;
horizontalMovementInput = 0f;
verticalMovementInput = 0f;
}
else if(animatorManager.isAimingGunn == false)
{
animatorManager.rightHandIK.weight = 0;
animatorManager.leftHandIK.weight = 0;
}

Answer 1

For this purpose you need to run a Tweener. This is a basic float Tweener that smoothly changes the floats by running Coroutine.
public IEnumerator DoTween(Func<float> getter , Action<float> setter, float targetValue, float duringTime = 1f)
{
var progress = 0f;
var init = getter();
while (progress < 1)
{
progress += Time.deltaTime/duringTime;
setter.Invoke(Mathf.Lerp(init, targetValue, progress));
yield return new WaitForEndOfFrame();
}
}
Do this to run Tweener in if code, Also, to zero the weight only, set zero in the targetValue parameter:
// How to run tweener?
// for E.G set IK weight to 1 during 2 seconds
StartCoroutine(DoTween(
() => animatorManager.leftHandIK.weight,
x => animatorManager.leftHandIK.weight = x,
1f, 2f
));
Also, if you want to create similar effects in the code, it suggests using the great DoTween unity plug-in.