如何在swift中创建可扩展的文本字段/标签？

Question

I need to figure out how to program something like this:

The text expands as the user clicks the down button and fold back to the short version after clicking up. Are there any libraries I could study? I am a beginner in programming and just need advice on how to approach this task, what guides to study and so on.

Answer 1

All you have to do is initially set the UILabel to have a numberOfLines of lets say 7 and line break mode to be .byTruncatingTail .

Then on button click simply change the numberOfLines to 0 and line break mode to be .byWordWrapping . Then when you wish to hide the text, just press the button and set the UILabel to its initial values.

Answer 2

To solve this issue read about AutoLayout . This is small example how it is possible to do.

This is coding part. This class contain IBOutlet for the height of the UITextView and button action.

class ViewController: UIViewController {

    let defaultHeight = 128
    let expectedHeight = 600
    var state: Bool = false

    @IBOutlet weak var height: NSLayoutConstraint!

    @IBAction func showAction(_ sender: Any) {
        UIView.animate(withDuration: 0.3, animations: {
                self.state = !self.state
                self.height.constant = CGFloat(self.state ? self.expectedHeight: self.defaultHeight)
                self.view.layoutIfNeeded()
        })
    }
}

This is from storyboard.

Answer 3

You can set an height constraint for your UILabel, and on the tap button event change the constraint constant to the contentsize of your label.

After your can animate it with

UIView.animate(duration)