how to detect when the iOS default keyboard type switches from text to numbers

问题

There are many posts about notifying the user when the keyboard type changes from things like the numberpad to default. This question is about knowing about when the user actually clicks on the [123] or the [ABC] button on the default keypad.. basically I want to know when this screen

changes to this screen

trying this:

-(void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText
{
    NSLog(@"::::::: this is text field type %d", searchBar.keyboardType);

naturally always give me back 0 which is the default key type.. since it's assuming both are of the same keyboard type.

回答1:

I ran into this same issue today and was sort of astounded that there is no way to detect that change from any notification or delegate method as I think this is a fairly common need. I am building a multi field text box input for capturing a pin code. I am auto-advancing to next / previous fields upon entering a value and don't want the keyboard to switch back to default each time I switch fields. I came up with this solution (note: This doesn't solve it perfectly because it requires the user to type something, but solves it for similar needs to this pin view).

I have a custom view called MyPinView, this view has var

var keyBoardType = UIKeyboardType.alphabet

and an array of UITextFields

var pinFields = [UITextField]()

that is laid out like so.

For a simplified version, I won't go through all the details of handling edge cases that require shouldChangeCharactersInRange to be implemented and will stick with my event handler implementation.

Basically, you need to see what text was typed and determine what keyboard to show when advancing fields (mine only supports numbers and letters switched with the abc / 123 button so I will ignore emoji and other types).

// MARK: UITextField Event
func textFieldDidChange(textField: UITextField) {
    // If the user typed one character, move to the next cell.
    if (textField.text?.count == 1) {
        let index = pinFields.index(of: textField)
        textField.resignFirstResponder()
        if (pinFields.count > index! + 1) {
            let pinField = pinFields[index! + 1]
            self.updateKeyboardTypeForString(input: textField.text)
            pinField.keyboardType = self.keyBoardType
            pinField.becomeFirstResponder()
        }
    } // If they deleted the character move to previous cell
    else if (textField.text?.count == 0) {
        let index = pinFields.index(of: textField)
        if (index! - 1 >= 0) {
            let pinField = pinFields[index! - 1]
            self.updateKeyboardTypeForString(input: pinField.text)
            pinField.keyboardType = self.keyBoardType
            pinField.becomeFirstResponder()
        }
    }
}

// MARK: - Keyboard Type Helper
func updateKeyboardTypeForString(input:String?) {
    let letters = NSCharacterSet.letters
    let digits = NSCharacterSet.decimalDigits
    let pinText = input == nil ? "" : input
    for uniScalar in pinText!.unicodeScalars {
        if letters.contains(uniScalar) {
            self.keyBoardType = UIKeyboardType.alphabet
        } else if digits.contains(uniScalar) {
            self.keyBoardType = UIKeyboardType.numbersAndPunctuation
        }
    }
}

This allows you to track where the keyboard last left off. Obviously if your text fields allow more than one character, you would need to grab only the last types character and pass it to updateKeyboardTypeForString. The main case where this won't help is in preserving keyboard state between input fields where the user has switched the keyboard, but not typed anything. Overall though, this helps this type of scenario to be more usable.

Hope this helps, happy programming.

回答2:

I think it is not possible to detect keyboard type switch. Maybe you can explain your problem or what do you want to achieve so we can find another workaround of your problem.

Regards

回答3:

Configuring the Keyboard for Text Objects You configure the attributes of the keyboard directly through the text objects of your app. The UITextField and UITextView classes both conform to the UITextInputTraits protocol, which defines the properties for configuring the keyboard. Setting these properties programmatically or in the Interface Builder inspector window causes the system to display the keyboard of the designated type.

@property(nonatomic) UIKeyboardType keyboardType

回答4:

There is not API to detect Keyboard changed: UITextField class reference

The definition of the keyboardType is part of the UITextInputTraits protocol. Setting a keyboardType, e.g. ASCII, is basically the standard keyboard showing the letter part of the keyboard self. If you set keyboardType to UIKeyboardTypeNumbersAndPunctuation, you get the same keyboard as the ASCII expect that the keyboard is shown with the number part of the keyboard first.

In Summary, ASCII and the Numbers and Punctuation keyboard are the same, three-screen keyboard that are presented in two different ways.

回答5:

You can detect changes to the keyboard type in textDidChange. If so, user have pick on keyboard button and you can check keyboardType property for a UITextField:

KeyboardType:UIKeyboardTypeNumberPad or UIKeyboardTypeDefault

So, yo can save the currently type, detect keyboard change, and compare the new keyboard type with first one.

来源：https://stackoverflow.com/questions/21255323/how-to-detect-when-the-ios-default-keyboard-type-switches-from-text-to-numbers

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ios

iphone

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uikeyboard