ios - UITextVIew 在屏幕上不可见

Question

我有以下两种观点:

 let captionTextView: UITextView = {
    let textField = UITextView(frame: CGRectMake(0,0, 250, 100))
    textField.text = "Enter caption..."
    textField.textColor = UIColor(red: (69/255.0), green: (209/255.0), blue: (153/255.0), alpha: 1.0)
    textField.editable = true
    textField.backgroundColor = UIColor.blueColor()
    textField.layer.cornerRadius = 5
    textField.layer.borderColor = UIColor(red: (69/255.0), green: (209/255.0), blue: (153/255.0), alpha: 1.0).CGColor
    textField.layer.borderWidth = 1
    textField.font = UIFont.boldSystemFontOfSize(15)
    return textField
}()

let infoLabel : UILabel = {
    let myLabel = UILabel()
    myLabel.textColor = UIColor(red: (69/255.0), green: (209/255.0), blue: (153/255.0), alpha: 1.0)
    myLabel.text = "Testing"
    myLabel.font = UIFont.systemFontOfSize(16.0)
    myLabel.textAlignment = NSTextAlignment.Center
    myLabel.adjustsFontSizeToFitWidth = true
    return myLabel
}()

我将它们添加到我的 View Controller 中，并具有以下约束:

func setupViews() {
    self.view.addSubview(captionTextView)
    self.view.addSubview(infoLabel)
    infoLabel.translatesAutoresizingMaskIntoConstraints = false
    captionTextView.translatesAutoresizingMaskIntoConstraints = false
    self.view.addConstraint(NSLayoutConstraint(item: infoLabel, attribute: .Top, relatedBy: .Equal, toItem: self.view, attribute: .Top, multiplier: 1, constant: 35))
    self.view.addConstraint(NSLayoutConstraint(item: infoLabel, attribute: .Leading, relatedBy: .Equal, toItem: self.view, attribute: .Leading, multiplier: 1, constant: 10))
    self.view.addConstraint(NSLayoutConstraint(item: infoLabel, attribute: .Trailing, relatedBy: .Equal, toItem: self.view, attribute: .Trailing, multiplier: 1, constant: -10))
    self.view.addConstraint(NSLayoutConstraint(item: captionTextView, attribute: .Top, relatedBy: .Equal, toItem: infoLabel, attribute: .Top, multiplier: 1, constant: 35))
    self.view.addConstraint(NSLayoutConstraint(item: captionTextView, attribute: .Leading, relatedBy: .Equal, toItem: self.view, attribute: .Leading, multiplier: 1, constant: 10))
    self.view.addConstraint(NSLayoutConstraint(item: captionTextView, attribute: .Trailing, relatedBy: .Equal, toItem: self.view, attribute: .Trailing, multiplier: 1, constant: -10))


}

标签正确显示了我想要的位置。 textView 在屏幕上根本不可见。如果我将它的类型更改为 textField 或 UILabel 它工作得很好，所以我不知道我在这里缺少哪些约束。我错过了什么？

Answer 1

您需要向 textView 添加底部 anchor ，因为它继承自 UIScrollView。

正如 Apple Docs 中所写:
https://developer.apple.com/documentation/uikit/uitextview