swift - 为什么我的 VFL 不工作？

Question

我有以下代码，我正在尝试实现添加到垂直 ScrollView 的动态图像。我想要它的约束，以便图像将自身设置在 ScrollView 的边界内。

但是结果是图像似乎保持其原始大小(比 ScrollView 大，因此图像被裁剪)

代码如下:

@IBOutlet weak var myScrollView: UIScrollView!
private let lettersModel:LettersModel = LettersModel();
private var imgs = [UIImageView]();

override func viewDidLoad() {
    super.viewDidLoad()

    myScrollView.backgroundColor = UIColor.brownColor()

    for var index=0; index<1; index++
    {

        let myImage:UIImage = UIImage(named: lettersModel.getLetterAt(index))!
        let myImageView:UIImageView = UIImageView()
        myImageView.image = myImage
        myImageView.contentMode = UIViewContentMode.ScaleAspectFit

        myScrollView.addSubview(myImageView)

        myImageView.translatesAutoresizingMaskIntoConstraints = false;

        myScrollView.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-[myImageView]-|", options: [], metrics: nil, views:["myImageView":myImageView] ))

        imgs.append(myImageView)

    }

}

Answer 1

UIView 位于 UIScrollView 内，无法根据其父级调整大小。您可以在 UIScrollView 中创建一个 UIView 并在 layoutSubviews 中更新宽度，然后将所有 UIView 添加到该 UIView 中。以下是您可以如何做到这一点:(为此，您需要设置 UIScrollView 的 contentSize 的高度，但您还必须设置它以使其滚动。)

class MyScrollView : UIScrollView {

    let contentView = UIView()

    override init (frame : CGRect) {
        super.init(frame : frame)
        addSubview(contentView)
    }

    convenience init () {
        self.init(frame:CGRect.zero)
    }

    required init(coder aDecoder: NSCoder) {
        fatalError("This class does not support NSCoding")
    }

    override func layoutSubviews() {
        contentView.frame.size.width = frame.width
        contentView.frame.size.height = contentSize.height
        super.layoutSubviews()
    }
}

var myScrollView = MyScrollView(frame: CGRect(x: 0, y: 0, width: 400, height: 600))
var imgs = [UIImageView]();

let myImage = UIImage(named: "achtergrond")
let myImageView:UIImageView = UIImageView()
myImageView.image = myImage
myImageView.contentMode = UIViewContentMode.ScaleAspectFit

myScrollView.contentSize.height = 1000 // <-- setting the contentSize
myScrollView.contentView.addSubview(myImageView) // <-- You add the UIImageView to the contentView

myImageView.translatesAutoresizingMaskIntoConstraints = false;
myScrollView.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-[myImageView]-|", options: [], metrics: nil, views:["myImageView":myImageView] ))

imgs.append(myImageView)