Attachment: Download

duplicates:

• SR-4827 Incorrect result resolving type for Obj-C block

Issue Description:

The problem is related when going from Swift->ObjC->Swift.

1. Create the Bar class and prefix the class for Objective C using @objc(...).

//Bar.swift
import Foundation

@objc(MKCBar)
public final class Bar: NSObject {
    var name: String?
}

2. Use forward declaration from the Objective C header file to avoid circular references.

//MKCFoo.h
#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@class MKCBar;

@interface MKCFoo : NSObject

@property (nonatomic, strong) MKCBar *bar;

-(instancetype)initWithBar:(MKCBar *)bar;

@end

NS_ASSUME_NONNULL_END

3. In the implementation use the autogenerated header file to get hold of the actual type.

//MKCFoo.m
#import "MKCFoo.h"
#import "ForwardAndBack-Swift.h"

@implementation MKCFoo

-(instancetype)initWithBar:(MKCBar *)bar {
    self = [super init];
    if (self) {
        self.bar = bar;
    }
    return self;
}

@end

4. Next add the Objective C header file to the bridging header to expose the class to Swift.

//ForwardAndBack-Bridging-Header.h
//
//  Use this file to import your target's public headers that you would like to expose to Swift.
//
#import "MKCFoo.h"

5. Finally try to use the property (which is a Swift class exposed using @objc) defined on the Objective C file.

//Baz.swift
import Foundation

public final class Baz {

    func executeFoo(_ foo: MKCFoo) {
        // This line below will not work as long as Bar.swift has the following @objc(MKCBar) attribute.
        // foo.bar
    }
}

6. Last but not least try to remove the name from @objc and update accordingly

        // Now try to replace @objc(MKCBar) in Bar.swift with just @objc and update the forward decleration in MKCfoo.h and correct the type in MKCfoo.m and now the line below will work but I've lost the prefix :-(
        // foo.bar

Please see the attached project or the problem described in this blog post https://cjwirth.com/tech/circular-references-swift-objc