SwiftUI / iOS | 在没有 NSNotification 的情况下获取键盘大小

Question

I would like to know if it is somehow possible to get the keyboard size of the device that my application is currently running on without any notification, because I'd like to place a Button exactly at that point inside of my View where the keyboard would end. There would be the possibility to change the position when the keyboard appears, but as I said before I want it to be there before it animates in.

Otherwise maybe there is any static size of the iOS keyboards, like eg 1/3 of the screen height of the device or something?

This is what I am trying to achieve:

Screenshot of hardcoded one on iPhone XS Max:

Thank you!

Answer 1

I have done it creating an extension for Publisher. However, it uses NotificationCenter

extension Publishers {
    static var keyboardHeight: AnyPublisher<CGFloat, Never> {
        let willShow = NotificationCenter.default.publisher(for: UIApplication.keyboardWillShowNotification)
            .map { $0.keyboardHeight }
        
        let willHide = NotificationCenter.default.publisher(for: UIApplication.keyboardWillHideNotification)
            .map { _ in CGFloat(0) }
        
        return MergeMany(willShow, willHide)
            .eraseToAnyPublisher()
    }
}

Also, you need to create a state variable for keyboardHeight

@State private var keyboardHeight: CGFloat = 0

Finally, you can observe the change in height using:

Text("")
       .onReceive(Publishers.keyboardHeight) {
                            self.keyboardHeight = $0
                        }

This is the approach I used for getting the height.