If I define a protocol in a base UIViewController will its children be able to conform to it in objective-c?

Question

I have:

UITableViewControllerA (Lists different ways to refine database product results)

UIViewControllerB (Controller associated with one of the rows from list above)

BaseController (Subclass of UIViewController, contains common code for controllers associated with rows in UITableViewControllerA and is their super class)

I can pass data to UIViewControllerB from UITableViewControllerA easily using the perpareForSegue method. I am now trying to pass data from UIViewControllerB to UITableViewControllerA when popViewControllerAnimated is called in my UIButton custom method that a user taps once they have made a selection of what to refine database product results with.

I decided to use delegation. UIViewControllerB which is subclass of a BaseController and in UITableViewControllerA I mentioned above that I have a list of ways to refine products:

Gender - Size - Colour - Price - Type

Rather than define my protocol below in each of their controllers I decided to define it in the BaseController like so:

#import <UIKit/UIKit.h>

@protocol BaseViewControllerDelegate <NSObject>

- (void)didTapDoneButtonWithSelection:(NSString *)selection; // use string for now to test

@end

@interface BaseViewController : UIViewController
@property (nonatomic, retain) id <BaseViewControllerDelegate> delegate;

- (UIButton *)clearButton;
- (UIButton *)doneButton;


@end

Then I went over to UIViewControllerB and accessed the delegate property and passed in the string to be sent over to UITableViewControllerA when done button is tapped:

- (void)doneButtonTapped:(id)sender {
    NSLog(@"DONE BUTTON TAPPED");
    [[self delegate] didTapDoneButtonWithSelection:@"THIS IS A TEST"];
    [[self navigationController] popViewControllerAnimated:YES];
}

In UITableViewControllerA I conform to the delegate protocol:

#import <UIKit/UIKit.h>
#import <Foundation/Foundation.h>
#import "BaseController.h"

@interface UITableViewControllerA : UITableViewController <BaseViewControllerDelegate>

@end

In UITableViewControllerA's implementation file I declare an instance var to hold the data passed over from the UIViewControllerB and display in a log message in viewWIllAppear. The didTapDoneButtonWithSelection method gets the data from the argument and stores it in the _test var:

@interface UITableViewControllerA ()

@end

@implementation UITableViewControllerA
{
    NSString *_test;
}

- (void)viewWillAppear:(BOOL)animated
{
    NSLog(@"%@", _test);
}

- (void)didTapDoneButtonWithSelection:(NSString *)selection
{
    _test = selection;
}

Issue:

My log message is giving me (null).

Is what I'm doing possible? or am I going about it the wrong way. If so please correct me with a code example.

Thanks for your time

Regards

Answer 1

I had to grab an instance of UIViewControllerB and set UITableViewControllerA as it's delegate in the prepareForSegue method:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{

    UITableViewControllerA *tvca = [segue destinationViewController];
    [tvca setDelegate:self];
}

However this feels odd, like there is another way I should be doing this.

Answer 2

EDIT:I think initially misunderstood the question.

If you are using segues the correct answer is the other one. If you aren't then it's:

In UITableViewControllerA when you are about to push the BaseViewController it should look something like this:

BaseViewController* base = [[BaseViewController alloc] init];
base.delegate = self;
[self.navigationController pushViewController:base animated:YES];