Calling Objective-C from Swift class causing linke

问题:

I'm trying to use RFDuino Objective-C library in Swift. It all sounds simple, I have called Objective-C from Swift classes before, no problem. This time however I hit the brick wall.

Created header file. Added header files to it. Swift can see the classes no problem. Project compiles fine.

The problem during build appears just after I try to call any of Objective classes

for example:

    override func viewDidLoad() {
         super.viewDidLoad()

        let rfDuinoManager: RFduinoManager = RFduinoManager.sharedRFduinoManager()

}

Undefined symbols for architecture x86_64: "_OBJC_CLASS_$_RFduinoManager", referenced from: __TMaCSo14RFduinoManager 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)

Im not sure what Im missing here. Link to the project here. https://www.dropbox.com/s/rza1ce01g4q5lp6/SmartHomeHub-stackoverflow.zip?dl=0

Thanks in advance for help. Honestly loosing hope now and considering rewrite whole library to Swift

回答1:

The problem is how the rfduino folder was added to the project. So

1. Remove rfduino folder (selecting rfduino folder in the project navigator panel on left and hit delete button, but when it asks to move it to the trash or just remove references, choose "remove references".

   

2. Your bridging header has an absolute path reference, I'd suggest removing that altogether by selecting it in build settings and hitting delete button:

   

3. Re-add rfduino files back to the project, this time, under "added folders" option, choose "create groups" rather than "create folder references". If you want it to prompt to create proper bridging header for you, don't select folder, but select the individual files:

   

   Also make sure that SmartHomeHub is checked below.

4. If you do that properly it will ask you to create bridging header automatically:

   

5. Go to this new bridging header and add your import lines again:

   

回答2:

This is a linker error, not a compiler error. Are you sure the RFduino class (source or library) is included in your project (open the project membership panel on the right in Xcode and make sure the box is checked to include the library in your target).

If it is included, make sure it has x86_64 code compiled into it. It might be an iOS library and is just compiled for ARM. You can check by finding the binary and running lipo on it from the command line.

lipo -info [name of RFduinolibrary.a(dylib,whatever)]

it should show x86_64 as an architecture, ala:

Architectures in the file are: i386 x86_64

回答3:

"The OPN [Debug] target overrides the OTHER_LDFLAGS build setting". This was the main issue. After adding $(inherited) in new line in other linker flags solved my issue.

回答4:

For me, Removing all the files in 'derived dir', removing reference to the frameworks in my project and connect again and etc didn't work anymore. Only worked to me is to set 'Build Active Architecture Only' to 'YES'.