Q:

Unity Lifecyle About Update & OnPointerClick , Who first call in the frame?

Unity lifecycle 
I checked the unity lifecycle , and I confuse about Update() and OnPointerClick()
Who calls first in the frame ??
public class Test : MonoBehaviour , IPointerClickHandler
{
    // who first ??
    private void Update()
    {

    }

    // who first ??
    public void OnPointerClick(PointerEventData eventData)
    {
        throw new NotImplementedException();
    }
}

A:

You can test this yourself with something like:
private int nUpdates = 0;

private void Update()
{
    Debug.Log("Update() number: " + nUpdates);
    nUpdates += 1;
}

private void OnPointerClick(PointerEventData eventData)
{
    Debug.Log("Update() number on click: " + nUpdates);
}

If, when you click, the "Update on click" message is shown first for a particular number, then that event fires first.
Let us know what turned out to be the case :-).
Spoiler:

 I'm guessing the click event will fire first, based on the documentation from Unity.

