要使输入附件视图垂直增长,您只需设置它autoresizingMask = .flexibleHeight
,计算它intrinsicContentSize
,然后让框架完成其余的工作。
编码:
class InputAccessoryView: UIView, UITextViewDelegate {
let textView = UITextView()
override init(frame: CGRect) {
super.init(frame: frame)
// This is required to make the view grow vertically
self.autoresizingMask = UIViewAutoresizing.flexibleHeight
// Setup textView as needed
self.addSubview(self.textView)
self.textView.translatesAutoresizingMaskIntoConstraints = false
self.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[textView]|", options: [], metrics: nil, views: ["textView": self.textView]))
self.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[textView]|", options: [], metrics: nil, views: ["textView": self.textView]))
self.textView.delegate = self
// Disabling textView scrolling prevents some undesired effects,
// like incorrect contentOffset when adding new line,
// and makes the textView behave similar to Apple's Messages app
self.textView.scrollEnabled = false
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override var intrinsicContentSize: CGSize {
// Calculate intrinsicContentSize that will fit all the text
let textSize = self.textView.sizeThatFits(CGSize(width: self.textView.bounds.width, height: CGFloat.max))
return CGSize(width: self.bounds.width, height: textSize.height)
}
// MARK: UITextViewDelegate
func textViewDidChange(_ textView: UITextView) {
// Re-calculate intrinsicContentSize when text changes
self.invalidateIntrinsicContentSize()
}
}
这种方法非常简单和可靠,因为它不需要修改约束或在每次视图大小更改时重新创建视图。