If i make a button in uniny, can i touch it with touch screen on phone, or only by mouse on PC?
GUI.Button(rect(0,0,50,50),BombTexture);
Does this work on touch screen?
If you haven’t tried it yet, the answer is : yes it does work with touch screen 
don’t forget to use if(GUI.Button…
Yes, it works exactly the same.
One important thing to note is that the GUI system in unity only handles 1 touch event at a time.
It took some digging but I remember seeing a perfect answer to this. Click the link for the explanation.