ios - 没有 Interface Builder 的 UIScrollView 和 Autolayout - ScrollView 如何获得它的高度？

Question

我正在不使用 Interface Builder/storyboards 来掌握 Xcode 6 和 iOS autolayout/constraints，但目前正在努力处理 ScrollView 。

我已经编写了以下代码(在我学习的过程中都是手写的!)它在屏幕上放置了一个包含内容 View 的 ScrollView ，而内容 View 又包含了几个额外的 View 。

滚动事件会在我滚动时正常触发。我遇到的问题是，当我放手时， ScrollView 只是弹回到开始，这表明它没有接收到内容高度。我认为。或者，也许我在某处搞砸了约束条件？

任何人都可以给我一些关于我可能在哪里出错的指示吗？

谢谢。

class TestScrollController: UIViewController, UIScrollViewDelegate {


    var scrollView: UIScrollView!
    var contentView = UIView()
    var blueView = UIView()
    var orangeView = UIView()



    override func viewDidLoad() {
        super.viewDidLoad()

        var superView = self.view

        var scrollView = UIScrollView()
        scrollView.setTranslatesAutoresizingMaskIntoConstraints(false)
        scrollView.scrollEnabled = true
        scrollView.alwaysBounceVertical = true
        scrollView.backgroundColor = UIColor.brownColor()
        scrollView.delegate = self
        superView.addSubview(scrollView);

        var contentView = UIView()
        contentView.setTranslatesAutoresizingMaskIntoConstraints(false)
        contentView.backgroundColor = UIColor.greenColor()
        scrollView.addSubview(contentView)

        let blueView = UIView()
        blueView.setTranslatesAutoresizingMaskIntoConstraints(false)
        blueView.backgroundColor = UIColor.blueColor()
        contentView.addSubview(blueView);

        let orangeView = UIView()
        orangeView.setTranslatesAutoresizingMaskIntoConstraints(false)
        orangeView.backgroundColor = UIColor.orangeColor()
        contentView.addSubview(orangeView);




        //scrollview Constraints
        let scrollViewConstraintTop = NSLayoutConstraint(
            item: scrollView,
            attribute: .Top,
            relatedBy: .Equal,
            toItem: superView,
            attribute: .Top,
            multiplier: 1.0,
            constant: 0
        )
        superView.addConstraint(scrollViewConstraintTop)

        let scrollViewConstraintRight = NSLayoutConstraint(
            item: scrollView,
            attribute: .Trailing,
            relatedBy: .Equal,
            toItem: superView,
            attribute: .Right,
            multiplier: 1.0,
            constant: 0
        )
        superView.addConstraint(scrollViewConstraintRight)

        let scrollViewConstraintBottom = NSLayoutConstraint(
            item: scrollView,
            attribute: .Bottom,
            relatedBy: .Equal,
            toItem: superView,
            attribute: .Bottom,
            multiplier: 1.0,
            constant: 0
        )
        superView.addConstraint(scrollViewConstraintBottom)

        let scrollViewConstraintLeft = NSLayoutConstraint(
            item: scrollView,
            attribute: .Leading,
            relatedBy: .Equal,
            toItem: superView,
            attribute: .Left,
            multiplier: 1.0,
            constant: 0
        )
        superView.addConstraint(scrollViewConstraintLeft)



        //contentView Constraints
        let contentViewConstraintTop = NSLayoutConstraint(
            item: contentView,
            attribute: .Top,
            relatedBy: .Equal,
            toItem: scrollView,
            attribute: .Top,
            multiplier: 1.0,
            constant: 0
        )
        superView.addConstraint(contentViewConstraintTop)

        let contentViewConstraintRight = NSLayoutConstraint(
            item: contentView,
            attribute: .Trailing,
            relatedBy: .Equal,
            toItem: scrollView,
            attribute: .Right,
            multiplier: 1.0,
            constant: 0
        )
        superView.addConstraint(contentViewConstraintRight)

        let contentViewConstraintBottom = NSLayoutConstraint(
            item: contentView,
            attribute: .Bottom,
            relatedBy: .Equal,
            toItem: scrollView,
            attribute: .Bottom,
            multiplier: 1.0,
            constant: 0
        )
        superView.addConstraint(contentViewConstraintBottom)

        let contentViewConstraintLeft = NSLayoutConstraint(
            item: contentView,
            attribute: .Leading,
            relatedBy: .Equal,
            toItem: scrollView,
            attribute: .Left,
            multiplier: 1.0,
            constant: 0
        )
        superView.addConstraint(contentViewConstraintLeft)



        //blueView Constraints
        let blueViewConstraintHeight = NSLayoutConstraint(
            item: blueView,
            attribute: .Height,
            relatedBy: .Equal,
            toItem: nil,
            attribute: .NotAnAttribute,
            multiplier: 1.0,
            constant: 100.0
        )
        superView.addConstraint(blueViewConstraintHeight)

        let blueViewConstraintTop = NSLayoutConstraint(
            item: blueView,
            attribute: .Top,
            relatedBy: .Equal,
            toItem: contentView,
            attribute: .Top,
            multiplier: 1.0,
            constant: 50.0
        )
        superView.addConstraint(blueViewConstraintTop)

        let blueViewConstraintLeft = NSLayoutConstraint(
            item: blueView,
            attribute: .Leading,
            relatedBy: .Equal,
            toItem: superView,
            attribute: .Left,
            multiplier: 1.0,
            constant: 50.0
        )
        superView.addConstraint(blueViewConstraintLeft)

        let blueViewConstraintRight = NSLayoutConstraint(
            item: blueView,
            attribute: .Trailing,
            relatedBy: .Equal,
            toItem: superView,
            attribute: .Right,
            multiplier: 1.0,
            constant: -50.0
        )
        superView.addConstraint(blueViewConstraintRight)



        //orangeView Constraints
        let orangeViewConstraintWidth = NSLayoutConstraint(
            item: orangeView,
            attribute: .Width,
            relatedBy: .Equal,
            toItem: nil,
            attribute: .NotAnAttribute,
            multiplier: 1.0,
            constant: 100.0
        )
        superView.addConstraint(orangeViewConstraintWidth)

        let orangeViewConstraintHeight = NSLayoutConstraint(
            item: orangeView,
            attribute: .Height,
            relatedBy: .Equal,
            toItem: nil,
            attribute: .NotAnAttribute,
            multiplier: 1.0,
            constant: 100.0
        )
        superView.addConstraint(orangeViewConstraintHeight)


        let orangeViewConstraintTop = NSLayoutConstraint(
            item: orangeView,
            attribute: .Top,
            relatedBy: .Equal,
            toItem: blueView,
            attribute: .Bottom,
            multiplier: 1.0,
            constant: 400.0
        )
        superView.addConstraint(orangeViewConstraintTop)

        let orangeViewConstraintBottom = NSLayoutConstraint(
            item: orangeView,
            attribute: .Bottom,
            relatedBy: .Equal,
            toItem: contentView,
            attribute: .Bottom,
            multiplier: 1.0,
            constant: 400.0
        )
        superView.addConstraint(orangeViewConstraintBottom)


        let orangeViewConstraintCenterX = NSLayoutConstraint(
            item: orangeView,
            attribute: .CenterX,
            relatedBy: .Equal,
            toItem: blueView,
            attribute: .CenterX,
            multiplier: 1.0,
            constant: 0.0
        )
        superView.addConstraint(orangeViewConstraintCenterX)


    }




    func scrollViewDidScroll(scrollView: UIScrollView) {
        println("scrollViewDidScroll")
    }




}

Answer 1

您可以使用 .contentsize(CGRECT) 设置 inside UIScrollView
内容的大小由于您没有设置 contentSize，因此您无法滚动到任何内容