以編程方式設置約束的問題

Question

我一直在爲這一整天奮鬥 - 我需要在我的導航欄中添加一個視圖作爲rightBarButtonItems，包含UILabel和UIImageView ..因此，我需要創建視圖以編程方式，以編程方式設置約束並將視圖添加爲rightBarButtonItems。

我試圖實現這一目標是：

。

。

而這就是我得到：

看來，無論我做什麼，我不能移動的向下箭頭。它必須在標籤的右側，並與中心Y對齊。

這是我的代碼：

//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] 

任何人有什麼我做錯了的想法？ :-)

Answer 1

您需要將約束添加到視圖。喜歡的東西：

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

Answer 2

爲了對標籤（codedLabel）的右側的箭頭（codedImageView），對準CenterY和德容器內（ContainerView），你需要以下限制：

• codedImageView.leading = codedLabel.trailing =>此將移動codedLabel的codedImageView右
• codedImageView.centerY = codedLabel.centerY =>這將垂直中心時，它
• codedImageView.trailing = containerView.trailing =>這將在最後和containerView中設置它。

這產生了以下的限制：

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 

見第一和第三約束有何不同？在你的例子中，你將它附加到codedLabel的左上角，而不是右中間。