如何在swift中移动具有故事板约束的UI对象?

So I am trying to create a simple moving animation for my UIImageView. Problem is I've had its constraints set in the storyview (3 constraints, top, left and right positions). So I cannot just alter coordinates - my image doesn't move if I do so. So I guess I have to alter my constraints first. But I cannot even get them in code.So I am trying to create a simple moving animat