设置UIView大小以适合subViews

我有一个UIView，其中包含两个具有动态高度的UILabel.我希望UIView适合UILabels的大小+一些填充.现在，我正在绘制标签，然后将UIView的宽度和高度约束设置为标签的组合大小.

I'm having a UIView that's containing two UILabels, which have dynamic heights. I want the UIView to fit the size of the UILabels + some padding. Right now I'm drawing the labels and then sets the UIView's width and height constraints to the combined size of the labels.

现在我正在这样做:

func populateWithMessage(headline: String?, message: String) {
    // Sets text
    self.headerLabel.text = headline
    self.messageLabel.text = message

    self.headerLabel.sizeToFit()
    self.messageLabel.sizeToFit()

    self.layoutSubviews()

    // Finding the label with the greatest width
    var longestLabel: UILabel!
    if self.headerLabel.frame.width > self.messageLabel.frame.width {
       longestLabel = self.headerLabel
   } else {
       longestLabel = self.messageLabel
   }
   
   let combinedLabelHeight = self.headerLabel.frame.height + self.messageLabel.frame.height
   
   // Update the container view's constraints
   self.containerViewWidtConstraint.constant = longestLabel.frame.width + 10
   self.containerViewHeightConstraint.constant = combinedLabelHeight + 10

   self.updateConstraints()
}

不幸的是，它不起作用.我正在使用Swift 2.3和Autolayout.

Unfortunately it doesn't work. I'm using Swift 2.3 and Autolayout.