This repo solves a problem I came across in using notifications to manage the iOS Keyboard.
When I first started managing the keyboard I would use separate Notifications in each ViewController.
Notification Method (Using Notification):
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
NotificationCenter.default.addObserver(self, selector: #selector(ViewController.keyboardNotification), name: NSNotification.Name.UIKeyboardWillChangeFrame, object: nil)
}
func keyboardNotification(notification: Notification) {
guard let userInfo = notification.userInfo else { return }
guard let endFrame = (userInfo[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue else { return }
let duration: TimeInterval = (userInfo[UIKeyboardAnimationDurationUserInfoKey] as? NSNumber)?.doubleValue ?? 0
let animationCurveRawNSN = userInfo[UIKeyboardAnimationCurveUserInfoKey] as? NSNumber
let animationCurveRaw = animationCurveRawNSN?.uintValue ?? UIViewAnimationOptions.curveEaseOut.rawValue
let animationCurve: UIViewAnimationOptions = UIViewAnimationOptions(rawValue: animationCurveRaw)
if endFrame.origin.y >= UIScreen.main.bounds.size.height {
lowerViewBottomConstraint.constant = 0
} else {
lowerViewBottomConstraint.constant = endFrame?.size.height ?? 0.0
}
view.animateConstraint(withDuration: duration, delay: TimeInterval(0), options: animationCurve, completion: nil)
}
}My problem was that I found myself writing this code again and again for every single ViewController. After experimenting a bit I found using a Singleton + Delegate pattern allowed me to reuse a bunch of code and organize all of the Keyboard Management in a single place!
Singleton + Delegate Method:
protocol KeyboardManagerDelegate: class {
func keyboardWillChangeFrame(endFrame: CGRect?, duration: TimeInterval, animationCurve: UIViewAnimationOptions)
}
class KeyboardManager {
static let sharedInstance = KeyboardManager()
weak var delegate: KeyboardManagerDelegate?
init() {
NotificationCenter.default.addObserver(self, selector: #selector(KeyboardManager.keyboardWillChangeFrameNotification), name: NSNotification.Name.UIKeyboardWillChangeFrame, object: nil)
}
@objc func keyboardWillChangeFrameNotification(notification: Notification) {
guard let userInfo = notification.userInfo else { return }
let endFrame = (userInfo[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue
let duration: TimeInterval = (userInfo[UIKeyboardAnimationDurationUserInfoKey] as? NSNumber)?.doubleValue ?? 0
let animationCurveRawNSN = userInfo[UIKeyboardAnimationCurveUserInfoKey] as? NSNumber
let animationCurveRaw = animationCurveRawNSN?.uintValue ?? UIViewAnimationOptions.curveEaseOut.rawValue
let animationCurve: UIViewAnimationOptions = UIViewAnimationOptions(rawValue: animationCurveRaw)
delegate?.keyboardWillChangeFrame(endFrame: endFrame, duration: duration, animationCurve: animationCurve)
}
}Now when I want to manage the keyboard from a ViewController all I need to do is set the delegate to that ViewController and implement any delegate methods.
class ViewController: UIViewController {
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
KeyboardManager.sharedInstance.delegate = self
}
}
// MARK: - Keyboard Manager
extension ViewController: KeyboardManagerDelegate {
func keyboardWillChangeFrame(endFrame: CGRect?, duration: TimeInterval, animationCurve: UIViewAnimationOptions) {
guard let endFrame = endFrame else { return }
if endFrame.origin.y >= UIScreen.main.bounds.size.height {
lowerViewBottomConstraint.constant = 0
} else {
lowerViewBottomConstraint.constant = (endFrame?.size.height ?? 0.0)
}
view.animateConstraint(withDuration: duration, delay: TimeInterval(0), options: animationCurve, completion: nil)
}
}This method is very customizable too! 🎉💯 Say we want to add functionality for NSNotification.Name.UIKeyboardWillHide. This is as easy as adding a method to our KeyboardManagerDelegate.
KeyboardManagerDelegate with NSNotification.Name.UIKeyboardWillHide:
protocol KeyboardManagerDelegate: class {
func keyboardWillChangeFrame(endFrame: CGRect?, duration: TimeInterval, animationCurve: UIViewAnimationOptions)
func keyboardWillHide(userInfo: [AnyHashable: Any])
}
class KeyboardManager {
static let sharedInstance = KeyboardManager()
weak var delegate: KeyboardManagerDelegate?
init() {
NotificationCenter.default.addObserver(self, selector: #selector(KeyboardManager.keyboardWillChangeFrameNotification), name: NSNotification.Name.UIKeyboardWillChangeFrame, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(KeyboardManager.keyboardWillHide), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
}
@objc func keyboardWillChangeFrameNotification(notification: Notification) {
guard let userInfo = notification.userInfo else { return }
let endFrame = (userInfo[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue
let duration: TimeInterval = (userInfo[UIKeyboardAnimationDurationUserInfoKey] as? NSNumber)?.doubleValue ?? 0
let animationCurveRawNSN = userInfo[UIKeyboardAnimationCurveUserInfoKey] as? NSNumber
let animationCurveRaw = animationCurveRawNSN?.uintValue ?? UIViewAnimationOptions.curveEaseOut.rawValue
let animationCurve: UIViewAnimationOptions = UIViewAnimationOptions(rawValue: animationCurveRaw)
delegate?.keyboardWillChangeFrame(endFrame: endFrame, duration: duration, animationCurve: animationCurve)
}
@objc func keyboardWillHide(notification: Notification) {
guard let userInfo = notification.userInfo else { return }
delegate?.keyboardWillHide(userInfo: userInfo)
}
}Say we only want to implement func keyboardWillHide(userInfo: [AnyHashable: Any]) in one UIViewController. We can also make this method optional.
typealias KeyboardManagerDelegate = KeyboardManagerModel & KeyboardManagerConfigureable
protocol KeyboardManagerModel: class {
func keyboardWillChangeFrame(endFrame: CGRect?, duration: TimeInterval, animationCurve: UIViewAnimationOptions)
}
@objc protocol KeyboardManagerConfigureable {
@objc optional func keyboardWillHide(userInfo: [AnyHashable: Any])
}Note: this pattern helps avoid overuse of
@objc. See HERE for more details!
In summary, I've found using a Singleton + Delegate to manage the keyboard is both more efficient and easier to use than using Notifications.
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