将Obj-c iOS应用程序转换为Swift时的链接器错误

Question

I have an iOS app written in Objective-C that I want to convert to Swift. Per Apple's Using Swift with Cocoa and Objective-C , I added a new Swift file with the same name as the Objective-C class it's replacing, put in a stub class declaration, and removed the original Objective-C class from the target.

The error is reporting that a symbol for the class can't be found at link time:

Undefined symbols for architecture x86_64:
  "_OBJC_CLASS_$_Chunk", referenced from:
      objc-class-ref in ViewController.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Here's my stub class declaration:

import Foundation

@objc class Chunk {

}

Is there some linker setting I can check?

And yes, I have cleaned my project, removed my derived data folder, and confirmed that the Swift file is in the Compile Sources section of the Build Phases .

I've also now reproduced the problem with a brand new project created in Xcode 6.1.1, available at https://github.com/dpassage/Foo .

Answer 1

On your link (Apple Dev)... you must check again "Importing Swift into Objective-C" :)

In your ViewController.m ... remove this line: #import "Chunk.h" and add this line: #import "Foo-Swift.h"

"The file: <#YourProjectName#>-Swift.h should already be created automatically in your project, even if you can not see it."

UPDATE

If Chunk.swift is descendant of an Objective-C class.. replace this @objc class Chunk with this: @objc class Chunk : NSObject (or conf with your requirement). If not... check "Using PURE Swift Classes in Objective-C" from here https://stackoverflow.com/a/24005242/1702413