94px to 79px
Yes, because a UISwitch is a control of fixed width and sets and determines its own size, you can simply create it using CGRectZero and then check its dimensions via its frame. This works in iOS4 and iOS5.
On iOS 4 you get a width of 94px and on iOS 5 you will get the width of 79px. You do this like so:
UISwitch *mySwitch = [[[UISwitch alloc] initWithFrame:CGRectZero] autorelease]; width = mySwitch.frame.size.width;
You can then use the width value to position accordingly in the parent view. Do that by setting the desired x,y position on the UISwitch frame.
Also I suggest you DO set AutoResizingMask margin values on the UISwitch so that it remains in the position you place it regardless of device orientation or type.