以编程方式设置约束的问题

Question

我现在一整天都在努力 - 我需要在我的导航栏中添加一个视图作为rightBarButtonItems，包含一个UILabel和一个UIImageView。因此，我需要以编程方式创建视图，设置约束以编程方式将视图添加为rightBarButtonItems。

我想要实现的目标是：

这就是我得到的：

似乎无论我做什么，我都无法移动向下箭头..它需要位于标签的右侧，并与centerY对齐。

这是我的代码：

    //Elements
    let containerView = UIView()
    containerView.frame = CGRect(x: 0, y: 0, width: 90, height: 30)
    containerView.backgroundColor = UIColor.blueColor()

    let codedLabel:UILabel = UILabel()
    codedLabel.frame = CGRect(x: 0, y: 0, width: 80, height: 30)
    codedLabel.textAlignment = .Center
    codedLabel.text = "FILTRER"
    codedLabel.numberOfLines = 1
    codedLabel.textColor = UIColor.redColor()
    codedLabel.font = UIFont(name: Constants.ubuntuBold, size: 18.0)!
    codedLabel.backgroundColor = UIColor.lightGrayColor()
    codedLabel.sizeToFit()

    let codedImageView: UIImageView = UIImageView()
    codedImageView.frame = CGRect(x: 0, y: 0, width: 10, height: 5.7)
    codedImageView.image = UIImage(named: "dragToRefreshArrow")
    codedImageView.backgroundColor = UIColor.cyanColor()

    containerView.addSubview(codedLabel)
    containerView.addSubview(codedImageView)

    containerView.sizeToFit()

    //Constraints
   containerView.translatesAutoresizingMaskIntoConstraints = false

    //Label
    NSLayoutConstraint(item: codedLabel, attribute: .Top, relatedBy: .Equal, toItem: containerView, attribute: .Top, multiplier: 1, constant: 0).active = true
    NSLayoutConstraint(item: codedLabel, attribute: .Bottom, relatedBy: .Equal, toItem: containerView, attribute: .Bottom, multiplier: 1, constant: 0).active = true
    NSLayoutConstraint(item: codedLabel, attribute: .Leading, relatedBy: .Equal, toItem: containerView, attribute: .Leading, multiplier: 1, constant: 0).active = true
    NSLayoutConstraint(item: codedLabel, attribute: .Trailing, relatedBy: .Equal, toItem: containerView, attribute: .Trailing, multiplier: 1, constant: 0).active = true

    //ImageView
    NSLayoutConstraint(item: codedImageView, attribute: .Leading, relatedBy: .Equal, toItem: codedLabel, attribute: .Leading, multiplier: 1, constant: 0).active = true
    NSLayoutConstraint(item: codedImageView, attribute: .Trailing, relatedBy: .Equal, toItem: containerView, attribute: .Trailing, multiplier: 1, constant: 0).active = true
    NSLayoutConstraint(item: codedImageView, attribute: .CenterY, relatedBy: .Equal, toItem: codedLabel, attribute: .Top, multiplier: 1, constant: 0).active = true

    let item = UIBarButtonItem()
    item.customView = containerView

    var negativeSpace:UIBarButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FixedSpace, target: nil, action: nil)
    negativeSpace.width = -10.0

    self.navigationItem.rightBarButtonItems = [negativeSpace, item]

任何人都知道我做错了什么？ ： - ）

Answer 1

您需要将约束添加到视图中。类似的东西：

let myConstraint = NSLayoutConstraint(....)
myConstraint.active = ture
self.containerView.addConstraints(myConstraint)

Answer 2

为了在标签右侧（codedLabel），对齐的CenterY和内部de容器（ContainerView）中有箭头（codedImageView），您需要以下约束：

• codedImageView.leading = codedLabel.trailing =＆gt;这将移动encodedLabel的codedImageView权利
• codedImageView.centerY = codedLabel.centerY =＆gt;这将垂直居中
• codedImageView.trailing = containerView.trailing =＆gt;这将在最后和containerView中设置它。

这产生了以下约束：

NSLayoutConstraint(item: codedImageView, attribute: .Leading, relatedBy: .Equal, toItem: codedLabel, attribute: .Trailing, multiplier: 1, constant: 0).active = true
NSLayoutConstraint(item: codedImageView, attribute: .Trailing, relatedBy: .Equal, toItem: containerView, attribute: .Trailing, multiplier: 1, constant: 0).active = true
NSLayoutConstraint(item: codedImageView, attribute: .CenterY, relatedBy: .Equal, toItem: codedLabel, attribute: .CenterY, multiplier: 1, constant: 0).active = true

了解第一个和第三个约束是如何不同的？在您的示例中，您将其附加到codedLabel的左上角而不是右中心。