Ios 将标签与PureLayout垂直对齐

我有一个简单的UIView子类，它包含一个标签。此子类具有以下init方法：

override init(frame: CGRect) {
    super.init(frame: frame)

    self.autoSetDimension(.Height, toSize: 44)
    titleLabel.backgroundColor = UIColor.clearColor()
    titleLabel.translatesAutoresizingMaskIntoConstraints = false
    titleLabel.numberOfLines = 0
    self.addSubview(titleLabel)

    titleLabel.text = "Some text"
    titleLabel.sizeToFit()

    titleLabel.autoPinEdgeToSuperviewEdge(.Leading, withInset: 20)
    titleLabel.autoPinEdgeToSuperviewEdge(.Trailing, withInset: 20)
    titleLabel.autoAlignAxisToSuperviewAxis(.Horizontal)
}

实际上，标签的文本在运行时可能会更改，但无论如何，当我运行应用程序时，我看不到标签在其父视图中垂直居中。。。有人能帮我吗

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提前谢谢

看看这个，如果它能帮到你

let label = UILabel()
    label.translatesAutoresizingMaskIntoConstraints = false

label.text = "Some dummy text"
self.view.addSubview(label)

let centreH = NSLayoutConstraint(item: label, attribute: NSLayoutAttribute.CenterX, relatedBy: NSLayoutRelation.Equal, toItem: self.view, attribute: NSLayoutAttribute.CenterX, multiplier: 1, constant: 1)

let centreV = NSLayoutConstraint(item: label, attribute: NSLayoutAttribute.CenterY, relatedBy: NSLayoutRelation.Equal, toItem: self.view, attribute: NSLayoutAttribute.CenterY, multiplier: 1, constant: 1)

self.view.addConstraint(centreH)
self.view.addConstraint(centreV)

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什么是PureLayout？有自动布局库吗？@BharatModi