以编程方式设置约束的问题

Question

我一直在为这一整天奋斗 - 我需要在我的导航栏中添加一个视图作为rightBarButtonItems，包含UILabel和UIImageView ..因此，我需要创建视图以编程方式，以编程方式设置约束并将视图添加为rightBarButtonItems。

我试图实现这一目标是：

。

。

而这就是我得到：

看来，无论我做什么，我不能移动的向下箭头。它必须在标签的右侧，并与中心Y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] 

任何人有什么我做错了的想法？ :-)

Answer 1

您需要将约束添加到视图。喜欢的东西：

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

Answer 2

为了对标签（codedLabel）的右侧的箭头（codedImageView），对准CenterY和德容器内（ContainerView），你需要以下限制：

• codedImageView.leading = codedLabel.trailing =>此将移动codedLabel的codedImageView右
• codedImageView.centerY = codedLabel.centerY =>这将垂直中心时，它
• codedImageView.trailing = containerView.trailing =>这将在最后和containerView中设置它。

这产生了以下的限制：

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 

见第一和第三约束有何不同？在你的例子中，你将它附加到codedLabel的左上角，而不是右中间。