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What I am trying to implement is a UITextField that sees words as characters. Specifically, im trying to see the mathemathical expression sin( as one character for example. I thought to solve this problem by implementing my own UITextInputDelegate. However, the four required functions from this protocol never get called when I implement or adopt this protocol. I tried implementing it in the following ways:

By subclassing a UITextField.

@interface BIDUItextFieldDelegate : UITextField < UITextInputDelegate >

By subclassing a NSObject.

@interface BIDTextfieldInputDelegate : NSObject < UITextInputDelegate >

The corresponding .m file contains:

@implementation BIDTextfieldInputDelegate


- (void)selectionWillChange:(id <UITextInput>)textInput
{
    NSLog(@"sWill");
}

- (void)selectionDidChange:(id <UITextInput>)textInput
{
    NSLog(@"sDid");
}

- (void)textWillChange:(id <UITextInput>)textInput
{
    NSLog(@"tWill");
}

- (void)textDidChange:(id <UITextInput>)textInput
{
    NSLog(@"tDid");
}

For example for the second approach (via subclassing NSObject), I do the following in the (id) init method in an additional custom UITextfield class which is displayed within the app:

//textInputDel is an instance of the custom NSObject class that adopts the above UITextInputDelegate protocol
self.textInputDel = [[BIDTextfieldInputDelegate alloc] init];

self.inputDelegate = self.textFieldDel;

Does anyone know what I am doing wrong, or has a better solution?

Florentijn Hogerwerf
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  • http://apptree.net/parser.htm May help. – Mick MacCallum Aug 14 '13 at 22:29
  • Thank you for your quick comment, I am using DDmathparser. Parsing itself all works fine, but for example being able to delete a few characters at the same time or restricted insertion possibilities within fixed words is more the problem I am dealing with at the moment. – Florentijn Hogerwerf Aug 14 '13 at 22:35
  • You can find a workaround for the problem [here](http://stackoverflow.com/questions/25158161/uitextinputdelegate-methods-not-functioning-correctly/27128185#27128185). – Daniel Nov 25 '14 at 13:40

1 Answers1

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UITextInputDelegate is not a protocol that you implement; rather, the system creates an object conforming to UITextInputDelegate, and assigns it as the .inputDelegate of a First Responder that conforms to UITextInput.

The methods of UITextInputDelegate are methods for your UITextInput-conforming responder to call on your .inputDelegate to inform it that you have changed your text or selection via means other than keyboard input.

Ben Cox
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