Question

I want to put something like this in a method for UITextField & UITextView.

- (void)changeKeyboardType:(UIKeyboardType)keyboardType {
    paymentTextView.keyboardType = UIKeyboardTypeAlphabet;
    [paymentTextView resignFirstResponder];
    [paymentTextView becomeFirstResponder];
}

How do I do this? I know I can create categories for both UITextField & UITextView but is it possible to do it in one shot?

By one shot, I mean add it to both classes with one protocol instead of making two categories, one for UITextView & one for UITextField. I’ve heard a protocol is similar to a Ruby module, but in a Ruby module, I can implement the method. In a protocol, it only seems that I can declare the method but not implement it. Can I also implement the method in the protocol, and then include this protocol in UITextField & UITextView?

How to add a method to an existing protocol in Cocoa? is close but not quite.

Answer 1

What about something like this?

// UIView+UITextInputTraits.h

@interface UIView (UITextInputTraits)
- (void)changeKeyboardType:(UIKeyboardType)keyboardType;    
@end


// UIView+Additions.m

#import "UIView+UITextInputTraits.h"

@implementation UIView (UITextInputTraits)

- (void)changeKeyboardType:(UIKeyboardType)keyboardType {
    if ([self conformsToProtocol:@protocol(UITextInputTraits)]) {
        id<UITextInputTraits> textInput = (id<UITextInputTraits>)self;
        if (textInput.keyboardType != keyboardType) {
            [self resignFirstResponder];
            textInput.keyboardType = keyboardType;
            [self becomeFirstResponder];
        }
    }
}

@end