Adding auto layout constraints between different view controller's view - ios

Question

As an academic exercise for a future UI, I am trying to add constraints between two table views, belonging to two different child view controllers of the root controller. In my RootViewController class below, tvc is displayed as expected in a 400x500 frame, but tvc2 is consuming the entire frame instead of being a 400x500 frame to the right of tvc. Basically, the constraints are apparently being ignored. I'm using an iPad sim in landscape.
override func viewDidLoad() {
super.viewDidLoad()
let v = self.view
v.backgroundColor = UIColor.greenColor()
var tvc :OrderTableViewController = OrderTableViewController(style: UITableViewStyle.Plain)
var tvc2 :OrderTableViewController = OrderTableViewController(style: UITableViewStyle.Plain)
self.addChildViewController(tvc)
self.addChildViewController(tvc2)
v.addSubview(tvc.view)
v.addSubview(tvc2.view)
tvc.didMoveToParentViewController(self)
tvc2.didMoveToParentViewController(self)
//tvc.view.setTranslatesAutoresizingMaskIntoConstraints(false)
//tvc2.view.setTranslatesAutoresizingMaskIntoConstraints(false)
//self.view.setTranslatesAutoresizingMaskIntoConstraints(false)
tvc.view.frame = CGRectMake(0, 0, 400, 500)
self.view.addConstraint(NSLayoutConstraint(
item: tvc2.view,
attribute: .Top,
relatedBy: .Equal,
toItem: tvc.view,
attribute: .Top,
multiplier: 1, constant: 0))
self.view.addConstraint(NSLayoutConstraint(
item: tvc2.view,
attribute: .Bottom,
relatedBy: .Equal,
toItem: tvc.view,
attribute: .Bottom,
multiplier: 1, constant: 0))
self.view.addConstraint(NSLayoutConstraint(
item: tvc2.view,
attribute: .Width,
relatedBy: .Equal,
toItem: nil,
attribute: .NotAnAttribute,
multiplier: 1, constant: 400))
self.view.addConstraint(NSLayoutConstraint(
item: tvc2.view,
attribute: .Left,
relatedBy: .Equal,
toItem: tvc.view,
attribute: .Right,
multiplier: 1, constant: 0))
}

Answer 1

This line,
tvc2.view.setTranslatesAutoresizingMaskIntoConstraints(false)
should be uncommented. When you add a view programmatically, and you're using constraints, you should always set that to false. On the other hand, you should not set that to false for controller's main view.
Also, the width constraint, since it only applies to tvc2, should be added to tvc2, not to self.view (although it should work either way).
It's also a bit odd, that you're adding one view using frames, and the other with constraints. It would be better to do both using the same paradigm.