ios - 仅当键盘快速出现时如何使scrollView滚动

Question

我正在使用 scrollview 来查看高度为 1000 的 View ，最初我不希望我的 scrollView 滚动。如果我点击任何文本字段，那么我希望我的 ScrollView 滚动，如果我返回键盘，那么我不希望 ScrollView 滚动。

在这里，当键盘出现时，我可以向上显示文本字段，但是当我返回键盘时，我无法将文本字段返回到其原始位置，并且当我返回键盘时，我不希望我的 View 滚动，

请在代码中帮助我。

class ViewController: UIViewController, UITextFieldDelegate {

@IBOutlet weak var scrolView: UIScrollView!
@IBOutlet weak var upTFLD: UITextField!
var activeTextField = UITextField()

@IBOutlet weak var downTFLD: UITextField!
override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.
    upTFLD.delegate = self
    downTFLD.delegate = self

    NotificationCenter.default.addObserver(self, selector: #selector(onKeyboardAppear(_:)), name: UIResponder.keyboardDidShowNotification, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(onKeyboardDisappear(_:)), name: UIResponder.keyboardDidHideNotification, object: nil)
}
@objc func onKeyboardAppear(_ notification: NSNotification) {

    let info = notification.userInfo!
    let rect: CGRect = info[UIResponder.keyboardFrameBeginUserInfoKey] as! CGRect
    let kbSize = rect.size
    let insets = UIEdgeInsets(top: 0, left: 0, bottom: kbSize.height+20, right: 0)
    self.scrolView.contentInset = insets
    self.scrolView.scrollIndicatorInsets = insets
    var visibleRect: CGRect = self.scrolView.convert(self.scrolView.bounds, to: self.view)
    visibleRect.size.height -= rect.size.height;
    let inputRect: CGRect = self.activeTextField.convert(self.activeTextField.bounds, to: self.scrolView)
    if (visibleRect.contains(inputRect)) {
        self.scrolView.scrollRectToVisible(inputRect, animated: true)
    }
}

@objc func onKeyboardDisappear(_ notification: NSNotification) {

    self.scrolView.contentInset = UIEdgeInsets.zero
    self.scrolView.scrollIndicatorInsets = UIEdgeInsets.zero
}

public func textFieldDidBeginEditing(_ textField: UITextField) {

    activeTextField = textField
}
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
    activeTextField.resignFirstResponder()
    return true
}
}

最初我不想滚动，如果我返回键盘，我需要文本字段回到原来的位置并且不再滚动。

只有键盘出现然后只有我需要滚动。请在代码中帮助我。

Answer 1

您只需要在键盘隐藏后立即设置 ScrollView 的 contentOffset。

创建一个变量来存储offsetBeforeShowKeyboard

var offsetBeforeShowKeyboard: CGFloat?

最初加载 View 时:

self.scrollView.isScrollEnabled = false

选择任何文本字段时:

public func textFieldDidBeginEditing(_ textField: UITextField) {
    self.scrollView.isScrollEnabled = true
    if (self.offsetBeforeShowKeyboard == nil) {
        self.offsetBeforeShowKeyboard = self.scrollView.contentOffset
    }
 }

键盘隐藏时

 @objc func onKeyboardDisappear(_ notification: NSNotification) {
    self.scrollView.isScrollEnabled = false
    if let offset = self.offsetBeforeShowKeyboard {
        self.scrolView.setContentOffset(offset, animated: true)    
    }
    self.offsetBeforeShowKeyboard = nil
 }