What is the animation speed of the keyboard appearing in iOS8?

The answer with the variable duration is right and work iOS 3 to 8, but with the new version of Swift, the answer's code is not working anymore. Maybe it is a mistake on my side, but I have to write:

let duration = aNotification.userInfo![UIKeyboardAnimationDurationUserInfoKey] as Double
let curve = aNotification.userInfo![UIKeyboardAnimationCurveUserInfoKey] as UInt

self.view.setNeedsLayout()
//baseConstraint.constant = 211
self.view.setNeedsUpdateConstraints()

UIView.animateWithDuration(duration, delay: 0.0, options: UIViewAnimationOptions(curve), animations: { _ in
    //self.view.layoutIfNeeded()
}, completion: { aaa in
    //(value: Bool) in println()
})

Looks like objectForKey is not working anymore and conversion is more strict.

swift3

    let duration = noti.userInfo?[UIKeyboardAnimationDurationUserInfoKey] as! NSNumber
    let curve = noti.userInfo?[UIKeyboardAnimationCurveUserInfoKey] as! NSNumber

    self.view.setNeedsLayout()

    UIView.animate(withDuration: TimeInterval(duration), delay: 0, options: [UIViewAnimationOptions(rawValue: UInt(curve))], animations: {
      self.view.layoutIfNeeded()
    }, completion: nil)

You can get the animation duration and the animation curve from the userInfo dictionary on the keyboardWillShow: notifications.

First register for the notification

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];

Then get the values from the notifications userInfo keys.

- (void)keyboardWillShow:(NSNotification*)notification {
    NSNumber *duration = [notification.userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
    NSNumber *curve = [notification.userInfo objectForKey: UIKeyboardAnimationCurveUserInfoKey];

   // Do stuff with these values.
}

There are a lot more of these keys, and you can also get them from the UIKeyboardWillDismiss notification.

This functionality is available all the way back to iOS 3.0 :D

Heres the docs:

https://developer.apple.com/library/ios/documentation/uikit/reference/UIWindow_Class/UIWindowClassReference/UIWindowClassReference.html#//apple_ref/doc/constant_group/Keyboard_Notification_User_Info_Keys

Swift Version

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

@objc func keyboardWillShow(_ notification: Notification) {
    let duration = notification.userInfo?[UIResponder.keyboardAnimationDurationUserInfoKey]
    let curve = notification.userInfo?[UIResponder.keyboardAnimationCurveUserInfoKey]
}