自定义uitextview直到特定高度

Question

我有一个具有聊天功能的应用程序,UITextview用于输入消息.UITextview高度必须是动态的(如果用户输入消息,则必须根据文本长度更改高度,直到特定高度).

我怎样才能做到这一点？

Answer 1

禁用滚动textView.

要将高度增加到特定值,然后启用滚动.

提供最大高度约束,然后将此代码添加到viewController

 class YourViewController: UIViewController, UITextViewDelegate
    {
        @IBOutlet weak var yourTextView: UITextView!

        let textViewMaxHeight: CGFloat = 100
        override func viewDidLoad()
        {
            super.viewDidLoad()
            yourTextView.delegate = self
        }

        func textViewDidChange(textView: UITextView)
        {
            if textView.contentSize.height >= self.textViewMaxHeight
            {
                textView.scrollEnabled = true
            }
            else
                {
                textView.frame.size.height = textView.contentSize.height
                textView.scrollEnabled = false
            }
        }
    }

Answer 2

向 textView 添加高度约束并创建一个出口，以便您可以对其进行调整。然后就可以使用 UIExfield 委托方法 textViewDidChange(_ textView: UITextView) 来调整高度。

func textViewDidChange(_ textView: UITextView) {

    // get the current height of your text from the content size
    var height = textView.contentSize.height

    // clamp your height to desired values
    if height > 90 {
        height = 90
    } else if height < 50 {
        height = 50
    }

    // update the constraint
    textViewHeightConstraint.constant = height
    self.view.layoutIfNeeded()
}

较短的版本...

func textViewDidChange(_ textView: UITextView) {
    let maxHeight: CGFloat = 90.0
    let minHeight: CGFloat = 50.0
    textViewHeightConstraint.constant = min(maxHeight, max(minHeight, textView.contentSize.height))           
    self.view.layoutIfNeeded()
}