Unity 3D: Changing sprite animation using UI button - animation

Question

I'm following this tutorial on youtube about changing sprite animation in code, and I was wondering if I could change this to changing sprite animation using UI button. does anyone knows how to do this. Thank you!
EDIT:
The script that I reposed kind of works thanks to your help, it changes the sprite image from image one to image two but what I'm basically trying to achieve is that each time that I click the UI button the sprite image will change from sprite image one (UI button click)> sprite image two (UI button click)> sprite image three (UI button click)> then repeat the process instead of the sprite image automatically changing itself.

Answer 1

Buttons have an OnClick event http://docs.unity3d.com/ScriptReference/UI.Button-onClick.html
You just create a method that gets called when the button is clicked, in your case the changing sprite code. Seen as you are using a timer though you will need to use something like a bool because onClick() only gets called once when clicked, not every frame.
Look https://www.youtube.com/watch?v=J5ZNuM6K27E
bool b_RunSpriteAnim;
public void onClick(){
b_RunSpriteAnim = true;
}
void Update(){
if (b_RunSpriteAnim)
//your anim sprite stuff
}
Then once the sprite anim has finished, just toggle b_RunSpriteAnim to false and reset the timer.
Edited:
You don't need a boolean. I only thought you wanted it because you were using a timer (as based on the Youtube link). If you just want to change the sprite immediately then you do not need it. As for Imagethree not working, it's because you have never included it in your code. It isn't clear what you are trying to achieve with Imagethree, if you included this in onClick as well it would just overwrite the image two that was just set, so I am not sure what you are looking to achieve.
public void onClick(){
this.gameObject.GetComponent<SpriteRenderer>().sprite = Imagetwo;
}
Second Edit:
public Sprite[] Images;
//Index starts at one because we are setting the first sprite in Start() method
private int _Index = 1;
void Start(){
//Set the image to the first one
this.gameObject.GetComponent<SpriteRenderer>().sprite = Images[0];
}
public void onClick(){
//Reset back to 0 so it can loop again if the last sprite has been shown
if (_Index >= Images.Length)
_Index = 0;
//Set the image to array at element index, then increment
this.gameObject.GetComponent<SpriteRenderer>().sprite = Images[_Index++];
}