UIPageViewController和AutoLayout：约束未正确应用

Question

I create a UIPageViewController programmatically and add it as a child to my container view-controler as shown below:

    override func viewDidLoad() {
    super.viewDidLoad()

    self.pageViewController = UIPageViewController(transitionStyle:.PageCurl, navigationOrientation:.Horizontal, options: nil)

    self.mainImageView!.userInteractionEnabled = true

    self.pageViewController.delegate = self
    self.pageViewController.dataSource = self.modelController

    self.addChildViewController(self.pageViewController)
    self.view.addSubview(self.pageViewController.view)

    self.pageViewController.didMoveToParentViewController(self)

}        

The problem is that the view of the UIPageViewController is not sized correctly as shown in the view hierarchy below. The view controllers returned by the data-source of the UIPageViewController contains a single UIScrollView . I have set the constraints of that UIScrollView such that the scrollView expands to the superview.

It seems to me that the problem stems from the fact that the scrollView constraints are "detached" from the constraints of the container view, but I don't know how to fix it using StoryBoard because these are views in different view-controllers. I am not very familiar with specifying constraints programmatically and my efforts to set the constraints programmatically have failed so far.

How can I fix this so that the scroll-view of the view-controller of UIPageViewController is properly contained inside the view of the container ViewController?

Answer 1

I had to add constraints programmatically to fix the problem. Note that I couldn't have added the auto layout constraints using IB because here I'm dealing with two views belonging to two different view-controllers in IB. The views are added programmatically as subviews because they are views of a UIPageViewController .

    override func viewDidLayoutSubviews() {
    self.pageViewController.view.setTranslatesAutoresizingMaskIntoConstraints(false)

    // Equal height constraint
    let constraint = NSLayoutConstraint(item: self.mainImageView!, attribute: .Height, relatedBy: .Equal, toItem: self.pageViewController.view, attribute: .Height, multiplier: 1.0, constant: 0)
    self.view.addConstraint(constraint)

    // Equal width constraint
    let constraint1 = NSLayoutConstraint(item: self.mainImageView!, attribute: .Width, relatedBy: .Equal, toItem: self.pageViewController.view, attribute: .Width, multiplier: 1.0, constant: 0)
    self.view.addConstraint(constraint1)

    // Equal top constraint
    let constraint2 = NSLayoutConstraint(item: self.mainImageView!, attribute: .Top, relatedBy: .Equal, toItem: self.pageViewController.view, attribute: .Top, multiplier: 1.0, constant: 0)
    self.view.addConstraint(constraint2)

    self.view.layoutSubviews()
}

Answer 2

I had the same problem and it has been solved by adding the code below in viewDidLoad()

pageViewController!.view.setTranslatesAutoresizingMaskIntoConstraints(false)
    let views = ["pageView": pageViewController!.view]

    var constH = NSLayoutConstraint.constraintsWithVisualFormat("H:|[pageView]|", options: .AlignAllCenterY, metrics: nil, views: views)
    view.addConstraints(constH)
    var constW = NSLayoutConstraint.constraintsWithVisualFormat("V:|[pageView]|", options: .AlignAllCenterX, metrics: nil, views: views)
    view.addConstraints(constW)

I hope that helps someone.