Creating UIViewController Category (Obj-C) similar to Extension Swift

Question

I'm trying to extend standard UIViewController with some custom methods.

#import <UIKit/UIKit.h>

@interface UIViewController (UIViewControllerExtension)
- (void) showNoHandlerAlertWithTitle:(NSString *)title andMessage:     (NSString*)message;
- (void) showAlertWithTitle:(NSString *)title andMessage:(NSString*)message  buttonTitles:(NSArray<NSString *>*)titles andHandler:(void (^)(UIAlertAction * action))handler;
@end

How can I use extended UIViewController now? I need to inherit my custom view controllers from extended UIViewController.

Answer 1

Create a file "UIViewController+Alert.h" containing:

#import <UIKit/UIKit.h>
@interface UIViewController (AlertExtension)
- (void) showNoHandlerAlertWithTitle:(NSString *)title andMessage:     (NSString*)message;
- (void) showAlertWithTitle:(NSString *)title andMessage:(NSString*)message  buttonTitles:(NSArray<NSString *>*)titles andHandler:(void (^)(UIAlertAction * action))handler;
@end

Then, create a file "UIViewController+Alert.m" that contains:

#import "UIViewController+Alert.h"
@implementation UIViewController (AlertExtension)
- (void) showNoHandlerAlertWithTitle:(NSString *)title andMessage:     (NSString*)message {
    // Insert code here
}

- (void) showAlertWithTitle:(NSString *)title andMessage:(NSString*)message  buttonTitles:(NSArray<NSString *>*)titles andHandler:(void (^)(UIAlertAction * action))handler {
    // Insert code here
}
@end

In say your "SampleViewController.h":

#import <UIKit/UIKit.h>

@interface SampleViewController : UIViewController
@end

Then in "SampleViewController.m":

#import "SampleViewController.h"
#import "UIViewController+Alert.h"

@implementation SampleViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    [self showNoHandlerAlertWithTitle:@"Hello" andMessage:@"World"];
}
@end