问题
The height of a keyboard on varying iOS devices is different. Does anybody know how I can get height of a device\'s keyboard programmatically?
回答1:
In Swift:
You can get the keyboard height by subscribing to the UIKeyboardWillShowNotification notification. (Assuming you want to know what the height will be before it's shown).
Something like this:
Swift 2
NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil)
Swift 3
NotificationCenter.default.addObserver(
self,
selector: #selector(keyboardWillShow),
name: NSNotification.Name.UIKeyboardWillShow,
object: nil
)
Swift 4
NotificationCenter.default.addObserver(
self,
selector: #selector(keyboardWillShow),
name: UIResponder.keyboardWillShowNotification,
object: nil
)
Then you can access the height in keyboardWillShow function like these:
Swift 2
func keyboardWillShow(notification: NSNotification) {
let userInfo: NSDictionary = notification.userInfo!
let keyboardFrame: NSValue = userInfo.valueForKey(UIKeyboardFrameEndUserInfoKey) as! NSValue
let keyboardRectangle = keyboardFrame.CGRectValue()
let keyboardHeight = keyboardRectangle.height
}
Swift 3
@objc func keyboardWillShow(_ notification: Notification) {
if let keyboardFrame: NSValue = notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue {
let keyboardRectangle = keyboardFrame.cgRectValue
let keyboardHeight = keyboardRectangle.height
}
}
Swift 4
@objc func keyboardWillShow(_ notification: Notification) {
if let keyboardFrame: NSValue = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue {
let keyboardRectangle = keyboardFrame.cgRectValue
let keyboardHeight = keyboardRectangle.height
}
}
回答2:
Swift 3.0 and Swift 4.1
1- Register the notification in the viewWillAppear method:
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: .UIKeyboardWillShow, object: nil)
2- Method to be called:
@objc func keyboardWillShow(notification: NSNotification) {
if let keyboardSize = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
let keyboardHeight = keyboardSize.height
print(keyboardHeight)
}
}
回答3:
Swift 4 and Constraints
To your tableview add a bottom constraint relative to the bottom safe area. In my case the constraint is called tableViewBottomLayoutConstraint.
@IBOutlet weak var tableViewBottomLayoutConstraint: NSLayoutConstraint!
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillAppear(notification:)), name: .UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillDisappear(notification:)), name: .UIKeyboardWillHide, object: nil)
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillShow , object: nil)
NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillHide , object: nil)
}
@objc
func keyboardWillAppear(notification: NSNotification?) {
guard let keyboardFrame = notification?.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue else {
return
}
let keyboardHeight: CGFloat
if #available(iOS 11.0, *) {
keyboardHeight = keyboardFrame.cgRectValue.height - self.view.safeAreaInsets.bottom
} else {
keyboardHeight = keyboardFrame.cgRectValue.height
}
tableViewBottomLayoutConstraint.constant = keyboardHeight
}
@objc
func keyboardWillDisappear(notification: NSNotification?) {
tableViewBottomLayoutConstraint.constant = 0.0
}
回答4:
Update Swift 4.2
private func setUpObserver() {
NotificationCenter.default.addObserver(self, selector: .keyboardWillShow, name: UIResponder.keyboardWillShowNotification, object: nil)
}
selector method:
@objc fileprivate func keyboardWillShow(notification:NSNotification) {
if let keyboardRectValue = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
let keyboardHeight = keyboardRectValue.height
}
}
extension:
private extension Selector {
static let keyboardWillShow = #selector(YourViewController.keyboardWillShow(notification:))
}
Update Swift 3.0
private func setUpObserver() {
NotificationCenter.default.addObserver(self, selector: .keyboardWillShow, name: .UIKeyboardWillShow, object: nil)
}
selector method:
@objc fileprivate func keyboardWillShow(notification:NSNotification) {
if let keyboardRectValue = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
let keyboardHeight = keyboardRectValue.height
}
}
extension:
private extension Selector {
static let keyboardWillShow = #selector(YourViewController.keyboardWillShow(notification:))
}
Tip
UIKeyboardDidShowNotification or UIKeyboardWillShowNotification might called twice and got different result, this article explained why called twice.
In Swift 2.2
Swift 2.2 deprecates using strings for selectors and instead introduces new syntax: #selector.
Something like:
private func setUpObserver() {
NSNotificationCenter.defaultCenter().addObserver(self, selector: .keyboardWillShow, name: UIKeyboardWillShowNotification, object: nil)
}
selector method:
@objc private func keyboardWillShow(notification:NSNotification) {
let userInfo:NSDictionary = notification.userInfo!
let keyboardFrame:NSValue = userInfo.valueForKey(UIKeyboardFrameEndUserInfoKey) as! NSValue
let keyboardRectangle = keyboardFrame.CGRectValue()
let keyboardHeight = keyboardRectangle.height
editorBottomCT.constant = keyboardHeight
}
extension:
private extension Selector {
static let keyboardWillShow = #selector(YourViewController.keyboardWillShow(_:))
}
回答5:
Shorter version here:
func keyboardWillShow(notification: NSNotification) {
if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
let keyboardHeight = keyboardSize.height
}
}
回答6:
Swift 4 .
Simplest Method
override func viewDidLoad() {
super.viewDidLoad()
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: .UIKeyboardWillShow, object: nil)
}
func keyboardWillShow(notification: NSNotification) {
if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
let keyboardHeight : Int = Int(keyboardSize.height)
print("keyboardHeight",keyboardHeight)
}
}
回答7:
// Step 1 :- Register NotificationCenter
ViewDidLoad() {
self.yourtextfield.becomefirstresponder()
// Register your Notification, To know When Key Board Appears.
NotificationCenter.default.addObserver(self, selector: #selector(SelectVendorViewController.keyboardWillShow(notification:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
// Register your Notification, To know When Key Board Hides.
NotificationCenter.default.addObserver(self, selector: #selector(SelectVendorViewController.keyboardWillHide(notification:)), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
}
// Step 2 :- These Methods will be called Automatically when Keyboard appears Or Hides
func keyboardWillShow(notification:NSNotification) {
let userInfo:NSDictionary = notification.userInfo! as NSDictionary
let keyboardFrame:NSValue = userInfo.value(forKey: UIKeyboardFrameEndUserInfoKey) as! NSValue
let keyboardRectangle = keyboardFrame.cgRectValue
let keyboardHeight = keyboardRectangle.height
tblViewListData.frame.size.height = fltTblHeight-keyboardHeight
}
func keyboardWillHide(notification:NSNotification) {
tblViewListData.frame.size.height = fltTblHeight
}
回答8:
Swift 5
override func viewDidLoad() {
// Registering for keyboard notification.
NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillShow(_:)), name: UIResponder.keyboardWillShowNotification, object: nil)
}
/* UIKeyboardWillShowNotification. */
@objc internal func keyboardWillShow(_ notification : Notification?) -> Void {
var _kbSize:CGSize!
if let info = notification?.userInfo {
let frameEndUserInfoKey = UIResponder.keyboardFrameEndUserInfoKey
// Getting UIKeyboardSize.
if let kbFrame = info[frameEndUserInfoKey] as? CGRect {
let screenSize = UIScreen.main.bounds
//Calculating actual keyboard displayed size, keyboard frame may be different when hardware keyboard is attached (Bug ID: #469) (Bug ID: #381)
let intersectRect = kbFrame.intersection(screenSize)
if intersectRect.isNull {
_kbSize = CGSize(width: screenSize.size.width, height: 0)
} else {
_kbSize = intersectRect.size
}
print("Your Keyboard Size \(_kbSize)")
}
}
}
回答9:
The method by ZAFAR007 updated for Swift 5 in Xcode 10
override func viewDidLoad() {
super.viewDidLoad()
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
}
@objc func keyboardWillShow(notification: NSNotification) {
if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
let keyboardHeight : Int = Int(keyboardSize.height)
print("keyboardHeight",keyboardHeight)
}
}
来源：https://stackoverflow.com/questions/31774006/how-to-get-height-of-keyboard