的UILabel出现在调试视图的层次结构，但不是在应用程序 [英] UILabel appear in debug view hierarchy but not in the application

问题描述

我有我的ViewController通过添加界面生成器一个UIView。

I have a UIView that I added in ViewController through the Interface Builder.

在我的code，我在这个UIView的每一个按钮是pressed时间创建一个标签：

In my code, I create a label in this UIView every time that a button is pressed:

func addToDisplay(stringToDisplay: String) {
    let label = UILabel(frame: CGRectMake(0, 0, 10, 10))
    label.text = stringToDisplay
    label.textColor = UIColor.redColor()
    label.textAlignment = .Right
    label.sizeToFit()
    label.adjustsFontSizeToFitWidth = true
    label.minimumScaleFactor = 0.5
    label.setTranslatesAutoresizingMaskIntoConstraints(false)

    var lastLabel: UILabel?

    if displayView.subviews.count > 0 {
        lastLabel = displayView.subviews[displayView.subviews.count - 1] as? UILabel
    }

    displayView.addSubview(label)

    var viewsDictionary = ["displayView": displayView, "label": label]

    // add constraints
    if let lastLabel = lastLabel {
        viewsDictionary["lastLabel"] = lastLabel
        displayView.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:[label(==20)]-0-[lastLabel]", options: nil, metrics: nil, views: viewsDictionary))
    } else {
        displayView.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:[label(==20)]-0-|", options: nil, metrics: nil, views: viewsDictionary))
    }
    displayView.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-0-[label]-0-|", options: nil, metrics: nil, views: viewsDictionary)) 
}

当我preSS的按钮，没有出现我的设备（也没有在模拟器上），但是当我检查的观点调试层次，它的存在的。我不明白为什么。任何想法？

When I press the button, nothing appear on my device (nor on the simulator) but when I check the view debug hierarchy, it's there. I don't understand why. Any idea?

编辑：

下面是两张截图：

EDIT2：

通过改变阿尔法比0不同的东西解决了...

Solved by changing alpha to something different than 0...

推荐答案

好吧，我想你需要告诉视图更新约束，写检查：

Well I think you need to tell the view to update constraints, write this and check:

[displayView updateConstraintsIfNeeded];

也测试你的 displayView 添加到 self.view ！
您正在使用的导航栏？如果是的话那么它是半透明？如果是的话那么你的self.view可能会从开始的（0,0）和导航栏是它的上面。如果这样的话，那么给予一定的 X'放大器;是，说的（100，100）并检查是否显示。

Also test that your displayView is added to self.view! Are you using Navigation Bar? If yes then is it translucent? If yes then your self.view may be starting from (0,0) and Navigation Bar is top of it. If this the case then give some x & y, say (100, 100) and check if it shows.

让我们知道，如果这有助于。

Let us know if this helped.

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