How to create custom view programmatically in swift having controls text field, button etc

The CGRectZero constant is equal to a rectangle at position (0,0) with zero width and height. This is fine to use, and actually preferred, if you use AutoLayout, since AutoLayout will then properly place the view.

But, I expect you do not use AutoLayout. So the most simple solution is to specify the size of the custom view by providing a frame explicitly:

customView = MyCustomView(frame: CGRect(x: 0, y: 0, width: 200, height: 50))
self.view.addSubview(customView)

Note that you also need to use addSubview otherwise your view is not added to the view hierarchy.