IOS swift View.frame.width is wrong

Hello i try to get the width of a UIView Element.

I tested it on an Iphone 4s Emulator.

I have an UIView Element on the main screen. Wich has 20 offset on the left and the right site of the screen.

When i call

UIScreen.mainScreen().bounds.width = 320

but

viewGame.frame.width = 240

but width of viewGame should be 260 so how do i get the real frame width ?

Edit: i am using autolayout to align the view