Objective-C callback from Swift

Question

Created Jul ’18

Replies 2

Boosts 0

Views 4.8k

Participants 3

In Swift application I have a

ViewController

, which call a new

modal

.

This

modal

have as

ViewController

Objective-C

implementation as

ViewController_obj_c

.

This

modal

is shown from Swift code and I want to call the callback property (with UIImage paramter), when the

Objective-C

code is done.

Me callback property

"signCompleteCallback"
doesn't work. How can I fill a callback property from

Swift

and call it inside

Objective-C

?

SwiftViewController.swift:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
  if segue.identifier == "showModalSegue" {
       if let nextVC = segue.destination as? ViewController_obj_c {

       nextVC.signCompleteCallback = #selector(self.Test) // filled objective-c selector here

       }
  }
}

@objc func Test(image: UIImage)
{
  debugPrint("Test method was called as callback with image parameter")
}

ViewController_obj_c.h:

@interface ViewController_obj_c : UIViewController 


@property SEL signCompleteCallback;

- (IBAction)Done_Clicked:(id)sender;

ViewController_obj_c.m:

- (IBAction)Done_Clicked:(UIButton *)sender
{
  UIGraphicsBeginImageContext(_dV.bounds.size);
  [_dV.layer renderInContext:UIGraphicsGetCurrentContext()];
  UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();

  [self signCompleteCallback]; // Here is the point when i want to call me callback and as a parameter i want to send image
}

Boost

Answer 1

OOPer OP

Jul ’18

Accepted Answer

I have posted an answer to the equivalent question in the stackoverflow.com.

(stackoverflow.com/questions/51186716/swift-callback-from-objective-c)

Please check it.

0

Answer 2

QuinceyMorris OP

Jul ’18

For the record, the original problem is in this line:

  [self signCompleteCallback]; // Here is the point when i want to call me callback and as a parameter i want to send image

Since "signCompleteCallback" is a property, this line just gets the selector for the "callback", but doesn't do anything with it. If you wanted to invoke the method, you would do something like this:

  [self performSelector: [self signCompleteCallback] withObject: image];

However, OOPer's alternate solution is better all round.

0