Use delegate in objective c class to call swift method

Question

I have two files

Question.m
Question.h

These two are written by Objective-C

MainView.swift

This is written by Swift

Question Class has the delegate

@interface Question : NSObject{

    id delegate;// put MainViewController here

    - (void)trythisfunction{
         [delegate test] // compiler doesn't find this method.
    } 
}

and I make class instance and put MainViewController as delegate of Question in MainViewController.swift

 class MainViewController: UIViewController {
        override func viewDidLoad(){
            q = Question()
            q.delegate = self // put self in delegate
         }
         func test(){
             NSLog("test is OK") 
         } 
 }

However Compiler found error [delegate test] Question.m:169:19: No known instance method for selector 'test:'

How can I solve this??

Rahul · Accepted Answer · 2017-05-20 13:08:01Z

1

You need to make few changes.

Below class declaration doesn't compile because you can't declare variables inside interface.

    @interface Question : NSObject{

    id delegate;

    - (void)trythisfunction {
         [delegate test] 
    } 
    }

I have fixed above and the class now looks like this,

 # Question.h file
 #import <Foundation/Foundation.h>

 @interface Question : NSObject
 @property (nonatomic, strong) id delegate;
 @end

Below is the implementation of the class

 # Question.m file
 #import "Question.h"

 @implementation Question

 @synthesize delegate;

 - (void)trythisfunction{
     [delegate test];
 }
 @end

As we are integrating this swift and so we will need a Bridging Header whose content look like.

  #import "Test.h"

Finally in your swift class now you can import this class

import UIKit

class MainViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        let q = Test()
        q.delegate = self
    }
    func test(){
        NSLog("test is OK")
    }
}

And above code works like a charm.

answered May 20, 2017 at 13:08

Rahul

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2 Comments

whitebear Over a year ago

Thank you very much finally I make it to call swift function from objective-c. However there are still some problems for handling variables. stackoverflow.com/questions/44093341/…

Rahul Over a year ago

Thanks for the upvote and accepting the answer @whitebear. I have answered the next question also. Hope it solves your problem.

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