Question

I have a UITextView subclass. UITextView class has some delegate protocols like

- (void)textViewDidChange:(UITextView *)textView;
- (void)textViewDidBeginEditing:(UITextView *)textView;

that I would like to use as they were from my custom class. In other words, if I use MyCustomTextViewClass from a class (lets call it classX), I have to do this and set the delegate:

MyCustomTextViewClass *box = [[MyCustomTextViewClass alloc] initWithFrame:
                                   CGRectMake(111.0f, 123.0f, 190.0f, 50.0f)];
// ... bla bla.. set other parameters
[box setDelegate:self];

but in order to set the delegate, I have to declare classX using

<MyCustomTextViewClassDelegate>

and to do that, I have to add UITextView’s delegate protocols to MyCustomTextViewClass.

How do I do that correctly?

simply do this on MyCustomTextViewClass?

@protocol MyCustomTextViewClassDelegate <NSObject>
@optional
- (void)textViewDidChange:(MyCustomTextViewClass *)textView;
- (void)textViewDidBeginEditing:(MyCustomTextViewClass *)textView;
@end

???
I don’t see how this could forward the delegate protocols from the UITextView…

thanks for any help.

Answer 1

EDIT: New answer. Please understand that a UITextView subclass does not need to declare its own delegate protocol. It works like this: not all rectangles are squares, but all squares are rectangles. Your MyCustomTextView will behave and respond to any messages that a UITextView responds to, and it will also send messages to its delegate just like a UITextView would. If you wanted to add additional delegate methods, that are not covered by UITextView, then you would create a brand new protocol.

Anyway, think about why you need to subclass UITextView. Are you adding a subview to it, like a character counting label? It would be useful to subclass, in that case. If you’re just creating a UITextView and changing some of the exposed properties, a custom subclass may be overkill. The reason I ask is because this question makes it seem that you don’t quite understand object inheritance. Not trying to be a jerk or anything here, I want to help you.

Anyway, to the code:

//===================================
//ClassX.h
//===================================
#import "MyCustomTextView.h"

@interface ClassX : UIViewController <UITextViewDelegate>

-(void)loadTextView;

@property (nonatomic, strong) MyCustomTextView *customTextView;

@end
//===================================
//ClassX.m
//===================================
#import "ClassX.h"

@implementation ClassX
@synthesize customTextView;

-(void)loadTextView {
    if (!customTextView) {
        self.customTextView = [[MyCustomTextView alloc] initWithFrame:CGRectZero];
    customTextView.delegate = self;
    }
    customTextView.publicString = @"Public String Property!";    
}

#pragma mark UITextViewDelegate

-(void)textViewDidChange:(UITextView *)textView {
    if (textView == customTextView) {
        //THIS IS CALLED A CAST :
        MyCustomTextView *castedVariable = (MyCustomTextView *)textView;
        //now the object castedVariable will be treated as a MyCustomTextView object
        //so you can access methods and variables declared by the class
        textView.publicString = @"Hello World!"; //XCode raises an error, UITextView doesn't have this property
        castedVariable.publicString = @"Hello World!"; //this works fine
        //handle textViewDidChange method
        //you are now interacting with self.customTextView
    } else {
        //is your ClassX also in charge of 
        //a different UITextView? Handle here
    }

}