Keyboard management in iOS Swift

Introduction

Keyboard management helps your app move content so users can see what they type. It stops the keyboard from hiding important parts of the screen.

When a user taps a text field and the keyboard covers the input area.

When you want to scroll the screen automatically to keep the active text field visible.

When you want to dismiss the keyboard by tapping outside the text field.

When you want to adjust the layout dynamically as the keyboard appears or disappears.

Syntax

iOS Swift

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)

@objc func keyboardWillShow(notification: Notification) {
  // Adjust UI here
}

Use NotificationCenter to listen for keyboard events.

Implement methods to adjust your UI when keyboard shows or hides.

Examples

Listen for keyboard showing event.

iOS Swift

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)

Get keyboard size to adjust UI.

iOS Swift

@objc func keyboardWillShow(notification: Notification) {
  if let keyboardFrame = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect {
    print("Keyboard height: \(keyboardFrame.height)")
  }
}

Dismiss keyboard when user taps outside.

iOS Swift

view.endEditing(true)

Sample App

This example moves the screen up when the keyboard appears so the text field stays visible. It moves back down when the keyboard hides. Tapping outside the text field closes the keyboard.

iOS Swift

import UIKit

class ViewController: UIViewController, UITextFieldDelegate {
  let textField = UITextField()
  
  override func viewDidLoad() {
    super.viewDidLoad()
    view.backgroundColor = .white
    
    textField.borderStyle = .roundedRect
    textField.placeholder = "Type here"
    textField.delegate = self
    textField.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(textField)
    
    NSLayoutConstraint.activate([
      textField.centerXAnchor.constraint(equalTo: view.centerXAnchor),
      textField.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -50),
      textField.widthAnchor.constraint(equalToConstant: 200)
    ])
    
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)
    
    let tapGesture = UITapGestureRecognizer(target: self, action: #selector(dismissKeyboard))
    view.addGestureRecognizer(tapGesture)
  }
  
  @objc func keyboardWillShow(notification: Notification) {
    if let keyboardFrame = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect {
      let keyboardHeight = keyboardFrame.height
      UIView.animate(withDuration: 0.3) {
        self.view.frame.origin.y = -keyboardHeight / 2
      }
    }
  }
  
  @objc func keyboardWillHide(notification: Notification) {
    UIView.animate(withDuration: 0.3) {
      self.view.frame.origin.y = 0
    }
  }
  
  @objc func dismissKeyboard() {
    view.endEditing(true)
  }

  deinit {
    NotificationCenter.default.removeObserver(self)
  }
}

Important Notes

Always remove observers if you add them manually to avoid memory leaks.

Use view.endEditing(true) to hide the keyboard easily.

Adjusting the view's frame is a simple way to move content, but using scroll views is better for complex layouts.

Summary

Keyboard management keeps input fields visible when typing.

Listen to keyboard show/hide notifications to adjust UI.

Dismiss keyboard by tapping outside input areas.

Practice

1. What is the main purpose of managing the keyboard in an iOS app?

easy

A. To disable typing in text fields

B. To keep input fields visible when the keyboard appears

C. To change the keyboard color

D. To automatically save user input

Solution

1. Step 1: Understand keyboard impact on UI

   The keyboard can cover input fields, making them hard to see or use.

2. Step 2: Purpose of keyboard management

   Managing the keyboard ensures input fields stay visible and accessible when typing.

3. Final Answer:

   To keep input fields visible when the keyboard appears -> Option B

4. Quick Check:

   Keyboard management = keep inputs visible [OK]

Hint: Keyboard management keeps inputs visible when typing [OK]

Common Mistakes:

• Thinking keyboard management changes keyboard color
• Believing it disables typing
• Assuming it auto-saves input

2. Which Swift method is used to dismiss the keyboard when tapping outside a UITextField?

easy

A. textField.resignFirstResponder()

B. textField.becomeFirstResponder()

C. textField.showKeyboard()

D. textField.hideKeyboard()

Solution

1. Step 1: Identify method to dismiss keyboard

   Calling resignFirstResponder() on a UITextField tells it to stop being active, hiding the keyboard.

2. Step 2: Check other options

   becomeFirstResponder() shows keyboard; showKeyboard() and hideKeyboard() do not exist in UIKit.

3. Final Answer:

   textField.resignFirstResponder() -> Option A

4. Quick Check:

   Dismiss keyboard = resignFirstResponder() [OK]

Hint: Use resignFirstResponder() to hide keyboard [OK]

Common Mistakes:

• Using becomeFirstResponder() which shows keyboard
• Trying non-existent methods like hideKeyboard()
• Not calling any method to dismiss keyboard

3. Given this Swift code snippet, what happens when the keyboard appears?

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)

@objc func keyboardWillShow(notification: NSNotification) {
  if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
    scrollView.contentInset.bottom = keyboardSize.height
  }
}

medium

A. Nothing happens when keyboard appears

B. The keyboard is hidden automatically

C. The scroll view scrolls to top

D. The scroll view's bottom inset increases to avoid keyboard overlap

Solution

1. Step 1: Understand notification observer

   The code listens for keyboard showing and calls keyboardWillShow function.

2. Step 2: Adjust scroll view inset

   Inside keyboardWillShow, it sets scrollView.contentInset.bottom to keyboard height, pushing content up.

3. Final Answer:

   The scroll view's bottom inset increases to avoid keyboard overlap -> Option D

4. Quick Check:

   Keyboard show adjusts scroll inset [OK]

Hint: Keyboard show notification adjusts scroll inset bottom [OK]

Common Mistakes:

• Thinking keyboard hides automatically
• Assuming scroll view scrolls to top
• Ignoring contentInset adjustment

4. What is wrong with this Swift code for dismissing the keyboard?

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
  view.endEditing(true)
}

medium

A. endEditing(true) does not dismiss keyboard

B. TouchesBegan is not called on UIViewController

C. It should call super.touchesBegan to propagate touch events

D. The method signature is incorrect

Solution

1. Step 1: Check method override

   Overriding touchesBegan requires calling super.touchesBegan to allow normal touch handling.

2. Step 2: Identify missing call

   The code misses super.touchesBegan, which can cause touch events to stop propagating.

3. Final Answer:

   It should call super.touchesBegan to propagate touch events -> Option C

4. Quick Check:

   Override touchesBegan must call super [OK]

Hint: Always call super in overridden touchesBegan [OK]

Common Mistakes:

• Not calling super.touchesBegan
• Thinking endEditing(true) doesn't dismiss keyboard
• Using wrong method signature

5. You want to move the view up when the keyboard appears and move it back down when it hides. Which approach correctly handles this in Swift?

hard

A. Listen to keyboardWillShow and keyboardWillHide notifications, adjust view frame accordingly

B. Only listen to keyboardDidShow notification and adjust view frame

C. Use a timer to check keyboard height every second and move view

D. Change the keyboard type to avoid covering the view

Solution

1. Step 1: Understand keyboard notifications

   keyboardWillShow and keyboardWillHide notify before keyboard appears/disappears, allowing smooth UI changes.

2. Step 2: Adjust view frame on both notifications

   Adjusting view frame up on show and back down on hide keeps UI consistent and responsive.

3. Step 3: Evaluate other options

   Listening only to keyboardDidShow is late; timer wastes resources; changing keyboard type doesn't solve overlap.

4. Final Answer:

   Listen to keyboardWillShow and keyboardWillHide notifications, adjust view frame accordingly -> Option A

5. Quick Check:

   Use willShow and willHide notifications for UI moves [OK]

Hint: Use willShow and willHide notifications to move views [OK]

Common Mistakes:

• Using only keyboardDidShow notification
• Polling keyboard height with timer
• Trying to change keyboard type to fix layout