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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
import UIKit
/**
* The keyboard state at the time of notification.
*/
public struct KeyboardState {
public let animationDuration: Double
public let animationCurve: UIView.AnimationCurve
private let userInfo: [AnyHashable: Any]
fileprivate init(_ userInfo: [AnyHashable: Any]) {
self.userInfo = userInfo
animationDuration = userInfo[UIResponder.keyboardAnimationDurationUserInfoKey] as! Double
// HACK: UIViewAnimationCurve doesn't expose the keyboard animation used (curveValue = 7),
// so UIViewAnimationCurve(rawValue: curveValue) returns nil. As a workaround, get a
// reference to an EaseIn curve, then change the underlying pointer data with that ref.
var curve = UIView.AnimationCurve.easeIn
if let curveValue = userInfo[UIResponder.keyboardAnimationCurveUserInfoKey] as? Int {
NSNumber(value: curveValue).getValue(&curve)
}
self.animationCurve = curve
}
/// Return the height of the keyboard that overlaps with the specified view. This is more
/// accurate than simply using the height of UIKeyboardFrameBeginUserInfoKey since for example
/// on iPad the overlap may be partial or if an external keyboard is attached, the intersection
/// height will be zero. (Even if the height of the *invisible* keyboard will look normal!)
public func intersectionHeightForView(view: UIView) -> CGFloat {
if let keyboardFrameValue = userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue {
let keyboardFrame = keyboardFrameValue.cgRectValue
let convertedKeyboardFrame = view.convert(keyboardFrame, from: nil)
let intersection = convertedKeyboardFrame.intersection(view.bounds)
return intersection.size.height
}
return 0
}
}
public protocol KeyboardHelperDelegate: AnyObject {
func keyboardHelper(_ keyboardHelper: KeyboardHelper, keyboardWillShowWithState state: KeyboardState)
func keyboardHelper(_ keyboardHelper: KeyboardHelper, keyboardDidShowWithState state: KeyboardState)
func keyboardHelper(_ keyboardHelper: KeyboardHelper, keyboardWillHideWithState state: KeyboardState)
func keyboardHelper(_ keyboardHelper: KeyboardHelper, keyboardDidHideWithState state: KeyboardState)
}
/**
* Convenience class for observing keyboard state.
*/
public class KeyboardHelper: NSObject {
public var currentState: KeyboardState?
private var delegates = [WeakKeyboardDelegate]()
public class var defaultHelper: KeyboardHelper {
struct Singleton {
static let instance = KeyboardHelper()
}
return Singleton.instance
}
/**
* Starts monitoring the keyboard state.
*/
public func startObserving() {
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardDidShow), name: UIResponder.keyboardDidShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardDidHide), name: UIResponder.keyboardDidHideNotification, object: nil)
}
deinit {
NotificationCenter.default.removeObserver(self)
}
/**
* Adds a delegate to the helper.
* Delegates are weakly held.
*/
public func addDelegate(delegate: KeyboardHelperDelegate) {
for weakDelegate in delegates where weakDelegate.delegate == nil {
// Reuse any existing slots that have been deallocated.
weakDelegate.delegate = delegate
return
}
delegates.append(WeakKeyboardDelegate(delegate))
}
@objc
func keyboardWillShow(notification: NSNotification) {
if let userInfo: [AnyHashable: Any] = notification.userInfo {
currentState = KeyboardState(userInfo)
for weakDelegate in delegates {
weakDelegate.delegate?.keyboardHelper(self, keyboardWillShowWithState: currentState!)
}
}
}
@objc
func keyboardDidShow(notification: NSNotification) {
if let userInfo = notification.userInfo {
currentState = KeyboardState(userInfo)
for weakDelegate in delegates {
weakDelegate.delegate?.keyboardHelper(self, keyboardDidShowWithState: currentState!)
}
}
}
@objc
func keyboardWillHide(notification: NSNotification) {
if let userInfo = notification.userInfo {
currentState = KeyboardState(userInfo)
for weakDelegate in delegates {
weakDelegate.delegate?.keyboardHelper(self, keyboardWillHideWithState: currentState!)
}
}
}
@objc
func keyboardDidHide(notification: NSNotification) {
if let userInfo = notification.userInfo {
currentState = KeyboardState(userInfo)
for weakDelegate in delegates {
weakDelegate.delegate?.keyboardHelper(self, keyboardDidHideWithState: currentState!)
}
}
}
}
private class WeakKeyboardDelegate {
weak var delegate: KeyboardHelperDelegate?
init(_ delegate: KeyboardHelperDelegate) {
self.delegate = delegate
}
}