Swift - 旋转的 UITextView 自动调整大小问题

Question

I use this function to make UITextView auto fit text content when typing. It works fine when the TextView is horizontal but does not work correctly when TextView is rotated. Any ideas how it can be fixed?

func textViewDidChange(_ textView: UITextView) {

    let newSize = textView.sizeThatFits(CGSize(width: CGFloat.greatestFiniteMagnitude, height: CGFloat.greatestFiniteMagnitude))
    textView.frame = CGRect(origin: textView.frame.origin, size: newSize)

}

Answer 1

According to the docs :

When the value of this property is anything other than the identity transform, the value in the frame property is undefined and should be ignored.

I think that might be why your code doesn't work - frame is undefined after you have applied a transform.

Try setting the transform back to identity before setting the frame:

let transform = textView.transform
textView.transform = .identity
let newSize = textView.sizeThatFits(CGSize(width: CGFloat.greatestFiniteMagnitude, height: CGFloat.greatestFiniteMagnitude))
textView.frame = CGRect(origin: textView.frame.origin, size: newSize)
textView.transform = transform

Answer 2

I have seen UITextView sometimes does not play good with transformations. Wrap your UITextView in a UIView. Set top, leading, bottom and trailing constaints of UITextView to UIView. Perform all the transformations on UIView. You should be good to go.

Answer 3

I have the same issue and I saw this problem, after that I fixed it like this;

extension UITextView {
  func calculateSize() {
    let currentTransform = transform
    transform = .identity
    
    let currentCenter = center
    let fixedWidth: CGFloat = font == nil ? 300 : text.widthOfString(usingFont: font!) + 16 // 300 for the worst case scenario and 16 is for leading and trailing spaces for content
    sizeThatFits(CGSize(width: fixedWidth, height: CGFloat.greatestFiniteMagnitude))
    
    let newSize = sizeThatFits(CGSize(width: fixedWidth, height: CGFloat.greatestFiniteMagnitude))
    var newFrame = frame
    newFrame.size = CGSize(width: max(newSize.width, fixedWidth), height: newSize.height)
    
    frame = newFrame
    center = currentCenter
    transform = currentTransform
    
    layoutIfNeeded()
  }
}