amichnia

import UIKit

extension String {

    private var attributedStringOptions: [NSAttributedString.DocumentReadingOptionKey: Any] {
        return [
            .documentType: NSAttributedString.DocumentType.html,
            .characterEncoding: String.Encoding.utf8.rawValue
        ]
    }

amichnia

// AdditionFrameworkInterop.m

#import "AdditionFrameworkInterop.h"
@import AdditionalSDK;

// You can adopt protocols from additional framework even if its weak linked
@interface AdditionFrameworkInterop() <PrimeNumberCheckerDelegate>  
@property (strong, nonatomic) PrimeNumberChecker *primeChecker;
@end

amichnia

// AdditionFrameworkInterop.h

#import <Foundation/Foundation.h>
#import <MainSDK/MainSDK-Swift.h>

@interface AdditionFrameworkInterop : NSObject
  
@property (weak, nonatomic) id<InteropDelegate> delegate;

+ (BOOL)additionalModuleAvailable;

amichnia

// Below would import or not, depending on whether it is linked
@import AdditionalSDK;

// ...

+ (BOOL)additionalModuleAvailable {
    if ([AdditonalSDK class]) { // Or any class from additional SDK
        return YES;
    } else {
        return NO;

amichnia

// MainSDK
#if canImport(AdditionalSDK)
import AdditionalSDK

public class NumberInspector: PrimeNumberCheckerDelegate {
    // ... adopt delegate protocol from AdditionalSDK
}
#else
public class NumberInspector {
    // ... cannot adopt protocol from AdditionalSDK

amichnia

// AdditionalSDK
@objc public class PrimeNumberChecker: NSObject {
    @objc public var delegate: PrimeNumberCheckerDelegate?
  
    @objc public func inspect(number: Int) {
      // ...
    }
}

@objc public protocol PrimeNumberCheckerDelegate {

amichnia

// MainSDK
public class NumberInspector {
    public weak var delegate: NumberInspectorDelegate?
    
    // ...
    
    public func inspect(number: Int) {
        // perform  inspection and notify delegate when done
    }
}

amichnia

// MyPrivateClass.m
#import "MyPrivateClass.h"

@implementation MyPrivateClass

@synthesize privateProperty;

+ (void)load {
    // This is called once, when module is being loaded,
    // "Invoked whenever a class or category is added to the Objective-C

amichnia

...

@objc(Factory)
internal class Factory: NSObject {
    private static var privateClassType: MyPrivateClass.Type!

    @objc static func registerPrivateClassType(type: MyPrivateClass.Type) {
        print("REGISTRATION CALLED WITH TYPE = \(type)")
        privateClassType = type
    }

amichnia

protocol SomeProtocol {
    init()
}
class SomeClass: SomeProtocol {
    ...
}

// This will work
let instance: SomeProtocol = SomeClass.init()