TPKeyboardAvoiding with Swift.

Node: Bài viết này mình chủ yếu là share code nhé. Mình tin rằng hầu hết các Develop ai cũng biết tới thư viện TPKeyboardAvoiding dùng để xử lý view khi keyboard ios và hiển thị.

Dưới đây mình đã convert Code Objective - C sang Swift để dùng cho các dự án của mình.

Source Code

import UIKit


// MARK: - TableView
class UITableViewSmart: UITableView {
    
    override var frame: CGRect {
        willSet(newValue) {
            if newValue.equalTo(frame) {
                return
            }
            super.frame = frame
        }
        didSet {
            if hasAutomaticKeyboardAvoidingBehaviour() {return}
            updateContentInset()
        }
    }
    
    override var contentSize: CGSize {
        willSet(newValue) {
            if newValue.equalTo(contentSize) {
                return
            }
            if hasAutomaticKeyboardAvoidingBehaviour() {
                super.contentSize = newValue
                return
            }
            super.contentSize = newValue
        }
        didSet {
            updateContentInset()
        }
    }
    
    override init(frame: CGRect, style: UITableViewStyle) {
        super.init(frame: frame, style: style)
        registerObserver()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        registerObserver()
    }
    
    override func awakeFromNib() {
        registerObserver()
    }
    
    deinit {
        removeObserver()
    }
    
    override func willMove(toSuperview newSuperview: UIView?) {
        super.willMove(toSuperview: newSuperview)
        if newSuperview != nil {
            cancelPerform()
        }
    }
    
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        hideKeyBoard()
        super.touchesEnded(touches, with: event)
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        callPerform()
    }
}

extension UITableViewSmart: UITextFieldDelegate {
    
    fileprivate func cancelPerform() {
        NSObject.cancelPreviousPerformRequests(withTarget: self, selector: #selector(assignTextDelegateForViewsBeneathView(_:)), object: self)
    }
    
    fileprivate func callPerform() {
        cancelPerform()
        Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(assignTextDelegateForViewsBeneathView(_:)), userInfo: nil, repeats: false)
    }
    
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        if !focusNextTextField() {
            textField.resignFirstResponder()
        }
        return true
    }
}

extension UITableViewSmart: UITextViewDelegate {
    
}

extension UITableViewSmart {
    
    fileprivate func hideKeyBoard() {
        findFirstResponderBeneathView(self)?.resignFirstResponder()
    }
    
    fileprivate func hasAutomaticKeyboardAvoidingBehaviour()->Bool {
        if #available(iOS 8.3, *) {
            if self.delegate is UITableViewController {
                return true
            }
        }
        return false
    }
    
    fileprivate func focusNextTextField()->Bool {
        return keyboard_focusNextTextField()
    }
    
    fileprivate func removeObserver() {
        NotificationCenter.default.removeObserver(self)
    }
    
    fileprivate func registerObserver() {
        if hasAutomaticKeyboardAvoidingBehaviour() { return }
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(keyboardWillShow(_:)),
                                               name: NSNotification.Name.UIKeyboardWillChangeFrame,
                                               object: nil)
        
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(keyboardWillHide(_:)),
                                               name: NSNotification.Name.UIKeyboardWillHide,
                                               object: nil)
        
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(scrollToActiveTextField),
                                               name: NSNotification.Name.UITextViewTextDidBeginEditing,
                                               object: nil)
        
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(scrollToActiveTextField),
                                               name: NSNotification.Name.UITextFieldTextDidBeginEditing,
                                               object: nil)
    }
}

// MARK: - CollectionView
class UICollectionViewSmart: UICollectionView {
    
    override var contentSize: CGSize {
        willSet(newValue) {
            if newValue.equalTo(contentSize) {
                return
            }
            super.contentSize = newValue
            updateContentInset()
        }
    }
    
    
    override var frame: CGRect{
        willSet(newValue) {
            if newValue.equalTo(self.frame) {
                return
            }
            super.frame = frame
            updateContentInset()
        }
    }
    
    override init(frame: CGRect, collectionViewLayout layout: UICollectionViewLayout) {
        super.init(frame: frame, collectionViewLayout: layout)
        registerObserver()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        registerObserver()
        
    }
    
    override func awakeFromNib() {
        super.awakeFromNib()
        registerObserver()
    }
    
    deinit {
        removeObserver()
    }
    
    override func willMove(toSuperview newSuperview: UIView?) {
        super.willMove(toSuperview: newSuperview)
        if newSuperview != nil {
            cancelPerform()
        }
    }
    
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        hideKeyBoard()
        super.touchesEnded(touches, with: event)
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        callPerform()
    }
}

extension UICollectionViewSmart: UITextFieldDelegate {
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        if !focusNextTextField() {
            textField.resignFirstResponder()
        }
        return true
    }
}

extension UICollectionViewSmart: UITextViewDelegate {
    
}

extension UICollectionViewSmart {
    
    fileprivate func cancelPerform() {
        NSObject.cancelPreviousPerformRequests(withTarget: self, selector: #selector(assignTextDelegateForViewsBeneathView(_:)), object: self)
    }
    
    fileprivate func callPerform() {
        cancelPerform()
        Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(assignTextDelegateForViewsBeneathView(_:)), userInfo: nil, repeats: false)
    }
    
    fileprivate func hideKeyBoard() {
        findFirstResponderBeneathView(self)?.resignFirstResponder()
    }
    
    fileprivate func focusNextTextField() -> Bool {
        return keyboard_focusNextTextField()
    }
    
    fileprivate func removeObserver() {
        NotificationCenter.default.removeObserver(self)
    }
    
    fileprivate func registerObserver() {
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(keyboardWillShow(_:)),
                                               name: NSNotification.Name.UIKeyboardWillChangeFrame,
                                               object: nil)
        
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(keyboardWillHide(_:)),
                                               name: NSNotification.Name.UIKeyboardWillHide,
                                               object: nil)
        
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(scrollToActiveTextField),
                                               name: NSNotification.Name.UITextViewTextDidBeginEditing,
                                               object: nil)
        
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(scrollToActiveTextField),
                                               name: NSNotification.Name.UITextFieldTextDidBeginEditing,
                                               object: nil)
    }
}

// MARK: - ScrollView
class UIScrollViewSmart: UIScrollView {
    
    // MARK: - Property
    override var contentSize: CGSize {
        willSet(newValue) {
            if newValue.equalTo(contentSize) {
                return
            }
            super.contentSize = newValue
            updateFromContentSizeChange()
        }
    }
    
    override var frame: CGRect {
        willSet(newValue) {
            if newValue.equalTo(frame) {
                return
            }
            super.frame = newValue
            updateContentInset()
        }
    }
    
    // MARK: - LifeCycle
    override init(frame: CGRect) {
        super.init(frame: frame)
        registerObserver()
    }
    
    override func awakeFromNib() {
        super.awakeFromNib()
        registerObserver()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        registerObserver()
    }
    
    deinit {
        removeObserver()
    }
    
    // MARK: - Override
    override func willMove(toSuperview newSuperview: UIView?) {
        super.willMove(toSuperview: newSuperview)
        if newSuperview != nil {
            cancelPerform()
        }
    }
    
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        hideKeyBoard()
        super.touchesEnded(touches, with: event)
    }
    
    
    override func layoutSubviews() {
        super.layoutSubviews()
        callPerform()
    }
}

// MARK: - Extension
extension UIScrollViewSmart: UITextFieldDelegate {
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        if !focusNextTextField() {
            textField.resignFirstResponder()
        }
        return true
    }
}

extension UIScrollViewSmart: UITextViewDelegate {
    // TO DO
}

extension UIScrollViewSmart {
    
    fileprivate func cancelPerform() {
        NSObject.cancelPreviousPerformRequests(withTarget: self, selector: #selector(assignTextDelegateForViewsBeneathView(_:)), object: self)
    }
    
    /// register Delegate
    fileprivate func callPerform() { /// when call -> cancel
        cancelPerform()
        Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(assignTextDelegateForViewsBeneathView(_:)), userInfo: nil, repeats: false)
    }
    
    fileprivate func hideKeyBoard() {
        findFirstResponderBeneathView(self)?.resignFirstResponder()
    }
    
    fileprivate func contentSizeToFit() {
        contentSize = calculatedContentSizeFromSubviewFrames()
    }
    
    fileprivate func focusNextTextField() -> Bool {
        return keyboard_focusNextTextField()
    }
    
    fileprivate func removeObserver() {
        NotificationCenter.default.removeObserver(self)
    }
    
    fileprivate func registerObserver() {
        /// UIKeyboardWillChangeFrame
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(keyboardWillShow(_:)),
                                               name: NSNotification.Name.UIKeyboardWillChangeFrame,
                                               object: nil)
        
        /// UIKeyboardWillHide
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(keyboardWillHide(_:)),
                                               name: NSNotification.Name.UIKeyboardWillHide,
                                               object: nil)
        
        /// UITextViewTextDidBeginEditing
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(scrollToActiveTextField),
                                               name: NSNotification.Name.UITextViewTextDidBeginEditing,
                                               object: nil)
        /// UITextFieldTextDidBeginEditing
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(scrollToActiveTextField),
                                               name: NSNotification.Name.UITextFieldTextDidBeginEditing,
                                               object: nil)
    }
}

// MARK: - Process Event
let kCalculatedContentPadding: CGFloat = 10
let kMinimumScrollOffsetPadding: CGFloat = 20

extension UIScrollView {
    
    @objc fileprivate func keyboardWillShow(_ notification:Notification) {
        guard let userInfo = notification.userInfo else { return }
        guard let rectNotification = notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue else {
            return
        }
        
        let keyboardRect = convert(rectNotification.cgRectValue , from: nil)
        if keyboardRect.isEmpty {
            return
        }
        
        let state = keyboardState()
        guard let firstResponder = findFirstResponderBeneathView(self) else { return}
        state.keyboardRect = keyboardRect
        if !state.keyboardVisible {
            state.priorInset = contentInset
            state.priorScrollIndicatorInsets = scrollIndicatorInsets
            state.priorPagingEnabled = isPagingEnabled
        }
        
        state.keyboardVisible = true
        isPagingEnabled = false
        if self is UIScrollViewSmart {
            state.priorContentSize = contentSize
            if contentSize.equalTo(CGSize.zero) {
                contentSize = calculatedContentSizeFromSubviewFrames()
            }
        }
        let duration = userInfo[UIKeyboardAnimationDurationUserInfoKey] as? Float ?? 0.0
        let curve = userInfo[UIKeyboardAnimationCurveUserInfoKey] as? Int ?? 0
        let options = UIViewAnimationOptions(rawValue: UInt(curve))
        UIView.animate(withDuration: TimeInterval(duration), delay: 0, options: options, animations: { [weak self]() -> Void in
            guard let strongSelf = self else {
                return
            }
            strongSelf.contentInset = strongSelf.contentInsetForKeyboard()
            let viewableHeight = strongSelf.bounds.size.height - (strongSelf.contentInset.top + strongSelf.contentInset.bottom)
            let point = CGPoint(x: strongSelf.contentOffset.x, y: strongSelf.idealOffsetForView(firstResponder, viewAreaHeight: viewableHeight))
            strongSelf.setContentOffset(point, animated: false)
            strongSelf.scrollIndicatorInsets = strongSelf.contentInset
            strongSelf.layoutIfNeeded()
        }) { (finished) -> Void in
        }
    }
    
    @objc fileprivate func keyboardWillHide(_ notification: Notification) {
        guard let userInfo = notification.userInfo else { return }
        guard let rectNotification = userInfo[UIKeyboardFrameEndUserInfoKey] as? NSValue else {
            return
        }
        let keyboardRect = convert(rectNotification.cgRectValue , from: nil)
        if keyboardRect.isEmpty {
            return
        }
        let state = keyboardState()
        if !state.keyboardVisible {
            return
        }
        state.keyboardRect = CGRect.zero
        state.keyboardVisible = false
        let duration = userInfo[UIKeyboardAnimationDurationUserInfoKey] as? Float ?? 0.0
        let curve = userInfo[UIKeyboardAnimationCurveUserInfoKey] as? Int ?? 0
        let options = UIViewAnimationOptions(rawValue: UInt(curve))
        UIView.animate(withDuration: TimeInterval(duration), delay: 0, options: options, animations: { [weak self]() -> Void in
            guard let strongSelf = self else {
                return
            }
            if strongSelf is UIScrollViewSmart {
                strongSelf.contentSize = state.priorContentSize
                strongSelf.contentInset = state.priorInset
                strongSelf.scrollIndicatorInsets = state.priorScrollIndicatorInsets
                strongSelf.isPagingEnabled = state.priorPagingEnabled
                strongSelf.layoutIfNeeded()
            }
        }) { (finished) -> Void in
        }
    }
    
    fileprivate func updateFromContentSizeChange() {
        let state = keyboardState()
        if state.keyboardVisible {
            state.priorContentSize = contentSize
        }
    }
    
    fileprivate func keyboard_focusNextTextField() -> Bool {
        guard let firstResponder = findFirstResponderBeneathView(self) else { return false}
        guard let view = findNextInputViewAfterView(firstResponder, beneathView: self) else { return false}
        Timer.scheduledTimer(timeInterval: 0.1, target: view, selector: #selector(becomeFirstResponder), userInfo: nil, repeats: false)
        return true
    }
    
    @objc fileprivate func scrollToActiveTextField() {
        let state = keyboardState()
        if !state.keyboardVisible { return }
        let visibleSpace = bounds.size.height - (contentInset.top + contentInset.bottom)
        let y = idealOffsetForView(findFirstResponderBeneathView(self), viewAreaHeight: visibleSpace)
        let idealOffset = CGPoint(x: 0, y: y)
        DispatchQueue.main.asyncAfter(deadline: .now() + Double((Int64)(0 * NSEC_PER_SEC)) / Double(NSEC_PER_SEC)) {[weak self] () -> Void in
            self?.setContentOffset(idealOffset, animated: true)
        }
    }
    
    fileprivate func findFirstResponderBeneathView(_ view:UIView) -> UIView? {
        for childView in view.subviews {
            if childView.responds(to: #selector(getter: isFirstResponder)) && childView.isFirstResponder {
                return childView
            }
            let result = findFirstResponderBeneathView(childView)
            if result != nil {
                return result
            }
        }
        return nil
    }
    
    fileprivate func updateContentInset() {
        let state = keyboardState()
        if state.keyboardVisible {
            contentInset = contentInsetForKeyboard()
        }
    }
    
    fileprivate func calculatedContentSizeFromSubviewFrames() ->CGSize {
        let wasShowingVerticalScrollIndicator = showsVerticalScrollIndicator
        let wasShowingHorizontalScrollIndicator = showsHorizontalScrollIndicator
        showsVerticalScrollIndicator = false
        showsHorizontalScrollIndicator = false
        var rect = CGRect.zero
        for view in self.subviews{
            rect = rect.union(view.frame)
        }
        rect.size.height += kCalculatedContentPadding
        showsVerticalScrollIndicator = wasShowingVerticalScrollIndicator
        showsHorizontalScrollIndicator = wasShowingHorizontalScrollIndicator
        return rect.size
    }
    
    fileprivate func idealOffsetForView(_ view:UIView?,viewAreaHeight:CGFloat) -> CGFloat {
        let contentSize = self.contentSize
        var offset:CGFloat = 0.0
        let subviewRect =  view != nil ? view!.convert(view!.bounds, to: self) : CGRect.zero
        var padding = (viewAreaHeight - subviewRect.height)/2
        if padding < kMinimumScrollOffsetPadding {
            padding = kMinimumScrollOffsetPadding
        }
        
        offset = subviewRect.origin.y - padding - self.contentInset.top
        if offset > (contentSize.height - viewAreaHeight) {
            offset = contentSize.height - viewAreaHeight
        }
        if offset < -contentInset.top {
            offset = -contentInset.top
        }
        return offset
    }
    
    fileprivate func contentInsetForKeyboard() -> UIEdgeInsets {
        let state = keyboardState()
        var newInset = contentInset
        let keyboardRect = state.keyboardRect
        newInset.bottom = keyboardRect.size.height - max(keyboardRect.maxY - bounds.maxY, 0)
        return newInset
        
    }
    
    fileprivate func viewIsValidKeyViewCandidate(_ view: UIView)->Bool {
        if view.isHidden || !view.isUserInteractionEnabled {return false}
        if view is UITextField {
            if (view as! UITextField).isEnabled {return true}
        }
        
        if view is UITextView {
            if (view as! UITextView).isEditable {return true}
        }
        return false
    }
    
    fileprivate func findNextInputViewAfterView(_ priorView:UIView,beneathView view:UIView, candidateView bestCandidate: inout UIView?) {
        let priorFrame = convert(priorView.frame, to: priorView.superview)
        let candidateFrame = bestCandidate == nil ? CGRect.zero : convert(bestCandidate!.frame, to: bestCandidate!.superview)
        
        var bestCandidateHeuristic = -sqrt(candidateFrame.origin.x*candidateFrame.origin.x + candidateFrame.origin.y*candidateFrame.origin.y) + ( Float(fabs(candidateFrame.minY - priorFrame.minY)) < .ulpOfOne ? 1e6 : 0)
        
        for childView in view.subviews {
            if viewIsValidKeyViewCandidate(childView) {
                let frame = convert(childView.frame, to: view)
                let heuristic = -sqrt(frame.origin.x*frame.origin.x + frame.origin.y*frame.origin.y)
                    + (Float(fabs(frame.minY - priorFrame.minY)) < .ulpOfOne ? 1e6 : 0)
                
                if childView != priorView && (Float(fabs(frame.minY - priorFrame.minY)) < .ulpOfOne
                    && frame.minX > priorFrame.minX
                    || frame.minY > priorFrame.minY)
                    && (bestCandidate == nil || heuristic > bestCandidateHeuristic) {
                    bestCandidate = childView
                    bestCandidateHeuristic = heuristic
                }
            } else {
                findNextInputViewAfterView(priorView, beneathView: view, candidateView: &bestCandidate)
            }
        }
    }
    
    fileprivate func findNextInputViewAfterView(_ priorView: UIView,beneathView view: UIView) ->UIView? {
        var candidate: UIView?
        findNextInputViewAfterView(priorView, beneathView: view, candidateView: &candidate)
        return candidate
    }
    
    @objc fileprivate func assignTextDelegateForViewsBeneathView(_ obj: AnyObject) {
        func processWithView(_ view: UIView) {
            for childView in view.subviews {
                if childView is UITextField || childView is UITextView {
                    initializeView(childView)
                } else {
                    assignTextDelegateForViewsBeneathView(childView)
                }
            }
        }
        
        if let timer = obj as? Timer, let view = timer.userInfo as? UIView {
            processWithView(view)
        } else if let view = obj as? UIView {
            processWithView(view)
        }
    }
    
    fileprivate func initializeView(_ view: UIView) {
        if let textField = view as? UITextField,
            let delegate = self as? UITextFieldDelegate, textField.returnKeyType == UIReturnKeyType.default &&
            textField.delegate !== delegate {
            textField.delegate = delegate
            let otherView = findNextInputViewAfterView(view, beneathView: self)
            textField.returnKeyType = otherView != nil ? .next : .done
        }
    }
    
    fileprivate func keyboardState() -> KeyboardState {
        if let state = objc_getAssociatedObject(self, &AssociatedKeysKeyboard.key) as? KeyboardState {
            return state
        } else {
            let state = KeyboardState()
            self.state = state
            return state
        }
    }
}
fileprivate class KeyboardState {
    var priorInset = UIEdgeInsets.zero
    var priorScrollIndicatorInsets = UIEdgeInsets.zero
    var keyboardVisible = false
    var keyboardRect = CGRect.zero
    var priorContentSize = CGSize.zero
    var priorPagingEnabled = false
}

extension UIScrollView {
    fileprivate enum AssociatedKeysKeyboard {
        static var key = "KeyBoardSmart"
    }
    
    fileprivate var state: KeyboardState? {
        get { // get
            let optionalObject = objc_getAssociatedObject(self, &AssociatedKeysKeyboard.key) as AnyObject?
            if let object = optionalObject {
                return object as? KeyboardState
            } else {
                return nil
            }
        }
        set { // set
            objc_setAssociatedObject(self, &AssociatedKeysKeyboard.key, newValue, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN_NONATOMIC)
        }
    }
}

Hướng dẫn sủ dụng

mình sẽ hướng dẫn với UIScrollView nhé, các view khác tương tự. Các bạn Config giống như bài viết trước của mình.

với view trên, khi keyboard hiển thị thì sẽ che mất đi view nằm gần dưới bottom.

chỉnh UIScrollView là UIScrollViewSmart. thành quả.