How to allocate static object defined in a Swift class inside an objective-C class?

Question

How do I access to the shared instance of "SharedManager" declared in my Swift file from my Objective-C class?

Steps:

I have declared an object in a Swift file as following:

Swift Class Declaration:

From this [instructions][1] I did:

// Swift class
class SharedManager{
    static let sharedInstance = SharedManager()
}

From Objective-C class:

In AppDelegate.m:

#import "ProjectName-Swift.h"

@class SharedManager;
@interface AppDelegate ()
@end

@implementation AppDelegate


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

// How do I access to the shared instance of "SharedManager" ?

}    

  [1]: http://stackoverflow.com/questions/24024549/using-a-dispatch-once-singleton-model-in-swift

Alexander · Answer 1 · 2016-10-12T09:09:00.540

1

To use a Swift class in Objective C, it must inherit from an Objective C class (such as NSObject), or be marked with @objc.

Either:

@objc class SharedManager {
    static let sharedInstance = SharedManager()
}

Or:

class SharedManager: NSObject {
    static let sharedInstance = SharedManager()
}

Then you can use it just like any other Objective C class:

SharedManager *manager = SharedManager.sharedInstance;

edited Oct 12 '16 at 09:09

answered Oct 12 '16 at 08:29

Alexander

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What does that mean? What's the issue? – Alexander Oct 12 '16 at 08:37
It says property sharedinstance not found – mm24 Oct 12 '16 at 08:38
I think you have to make `sharedInstance` `public` – Alexander Oct 12 '16 at 08:38
@mm24: SharedManager must inherit from NSObject in order to be used in Objective-C. – Martin R Oct 12 '16 at 08:50
@mm24 oh yeah, it must either inherit from an Objective C class, or be annotated with `@objc` – Alexander Oct 12 '16 at 09:06

score 1 · Answer 2 · answered Feb 28 '19 at 15:21

Maybe late to the party, but you should also prepend the @objc marker also for the shared instance:

@objc
class VoiceShortcutsManager: NSObject {
    @objc static let shared = VoiceShortcutsManager()

    private override init() {
        super.init()
        updateVoiceShortcuts(nil)
    }

...

}

This way you can safely access the shared instance in objective-c:

...

[VoiceShortcutsManager shared];

...

score 0 · Answer 3 · answered Oct 12 '16 at 08:58

You need to do the following:

#import "ProjectName-Swift.h" in the Objective-C implementation file (.m) where you want to refer to the Swift type.
Subclass your SharedManager from NSObject:

class SharedManager: NSObject {
    static let sharedInstance = SharedManager()
}

This will work at least with Swift 2.3 and 3 (i.e. Xcode 8 & current macOS / iOS SDK versions, with or without "Use Legacy Swift Language Version" on in build configuration). I fail to remember if prior to Swift 2.3 you can make the above work with additionally marking the class with the @objc attribute or whether static variables declared in Swift are entirely unavailable to Objective-C code?

Bassam · Answer 4 · 2016-10-12T11:14:35.710

-1

 class MyClass { 
    private static let _sharedInstance = MyClass() 

    class func sharedInstance() -> MyClass { return _sharedInstance } 
}

Retrieve the singleton via

MyClass.sharedInstance()

edited Oct 12 '16 at 11:14

answered Oct 12 '16 at 08:29

Bassam

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17

The bridging header file is for exposing Objective C to Swift, the opposite of what OP needs. OP needs to use the auto-generated header file created by Xcode, which they already have imported (`#import ProjectName-Swift.h`). – Alexander Oct 12 '16 at 08:31
I have the bridge header to export Swift classes as Alexander said – mm24 Oct 12 '16 at 08:37
class MyClass { private static let _sharedInstance = MyClass() class func sharedInstance() -> MyClass { return _sharedInstance } } Retrieve the singleton via MyClass.sharedInstance() – Bassam Oct 12 '16 at 08:43
Hi Bassam, adding the method worked. Would you be able to edit your answer reflecting this and then I'll accept it? – mm24 Oct 12 '16 at 09:14

How to allocate static object defined in a Swift class inside an objective-C class?

4 Answers4