Linker error when passing data from Swift to Objective C - ios

Question

I am using FXForm Library and want to get data from my Swift file in Objective C file function.
Demo Project Link
Swift Code Implimnetation:
let fontName = "HelveticaNeue"
let fontSizeLarge:CGFloat = 14.0
var hiddenElementFromFormIndex = [Int]()
//fx form variables
#objc class FXFormVariables : NSObject {
public override init() {}
class func FXFontName() -> String { return fontName }
class func FXFontSize() -> CGFloat { return fontSizeLarge }
class func FXHiddenCell() -> NSArray { return hiddenElementFromFormIndex as NSArray }
}
In Objective C file, I am getting error when we write below like:
NSArray *hideArray = [FXFormVariables FXHiddenCell];
I created the bridge header file correctly and Target Membership is checked in the Objective C file.
Error I am getting:
Undefined symbols for architecture x86_64:
"_OBJC_CLASS_$__TtCC13Social_Engine11AppDelegate15FXFormVariables", referenced from:
objc-class-ref in FXForms.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Architectures and Valid Architectures are:
armv7 and armv64

Answer 1

To use Swift class inside Objective-C file you need to import Xcode-generated header file in your Objective-C file.
#import "ProductModuleName-Swift.h"
I created a Test project with the same name.
Swift File:
//
// FXFormVariables.swift
// Test
//
// Created by Puneet Sharma2 on 12/07/17.
// Copyright © 2017 com.puneet.sh2525. All rights reserved.
//
import Foundation
import UIKit
let fontName = "HelveticaNeue"
let fontSizeLarge:CGFloat = 14.0
var hiddenElementFromFormIndex = [Int]()
//fx form variables
#objc class FXFormVariables : NSObject {
public override init() {}
class func FXFontName() -> String { return fontName }
class func FXFontSize() -> CGFloat { return fontSizeLarge }
class func FXHiddenCell() -> NSArray { return hiddenElementFromFormIndex as NSArray }
}
Objective-C File
#import "ABC.h"
#import "Test-Swift.h"
#implementation ABC
- (void)drawRect:(CGRect)rect {
NSArray *hideArray = [FXFormVariables FXHiddenCell];
}
You can read more about it here.

Answer 2

Literally I spent hours trying to figure out why this was happening with one of my swift files that i was importing into my Objc codebase, and the real reason was due to the use of a nested class.
Such as:
#objc public class MyClass {
#objc public class SecondClass {}
}
And if I tried using SecondClass in my objective-c code, I would the Apple Mach O-Link errors of death. So the solution was to de-nest the class you want to use.
#objc public class MyClass {}
#objc public class SecondClass {}