NSKeyedUnarchiver fails to decode a custom object

问题:

I'm trying a basic implementation of the NSCoding protocol in swift, but it seems I can't success to unarchive an object after it has been correctly archived.

Here's my attempt

import Cocoa

class User: NSObject, NSCoding {
    var name: String

    init(name: String) {
        self.name = name
    }

    init(coder aDecoder: NSCoder!) {
        self.name = aDecoder.decodeObjectForKey("name") as String
    }

    func encodeWithCoder(aCoder: NSCoder!) {
        aCoder.encodeObject(name, forKey: "name")
    }
}

let user = User(name: "Gabriele")
let encodedUser = NSKeyedArchiver.archivedDataWithRootObject(user)
let decodedUser = NSKeyedUnarchiver.unarchiveObjectWithData(encodedUser) as User

Running this in the playground, it launches an exception on the last line. Here's the details

Execution was interrupted, reason: signal SIGABRT.
The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation.
* thread #1: tid = 0x433bc, 0x00007fff9325e37a libsystem_kernel.dylib`__pthread_kill + 10, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
  * frame #0: 0x00007fff9325e37a libsystem_kernel.dylib`__pthread_kill + 10
    frame #1: 0x00007fff8c3618f7 libsystem_pthread.dylib`pthread_kill + 90
    frame #2: 0x00007fff935b462b libsystem_c.dylib`abort + 129
    frame #3: 0x00007fff8813fa21 libc++abi.dylib`abort_message + 257
    frame #4: 0x00007fff881679d1 libc++abi.dylib`default_terminate_handler() + 267
    frame #5: 0x00007fff8538050d libobjc.A.dylib`_objc_terminate() + 103
    frame #6: 0x00007fff881650a1 libc++abi.dylib`std::__terminate(void (*)()) + 8
    frame #7: 0x00007fff88164b30 libc++abi.dylib`__cxa_throw + 121
    frame #8: 0x00007fff8537c6a7 libobjc.A.dylib`objc_exception_throw + 341
    frame #9: 0x00007fff8ec1962d CoreFoundation`+[NSException raise:format:] + 205
    frame #10: 0x00007fff90dd9382 Foundation`_decodeObjectBinary + 2682
    frame #11: 0x00007fff90dd8796 Foundation`_decodeObject + 278
    frame #12: 0x00007fff90dfe159 Foundation`+[NSKeyedUnarchiver unarchiveObjectWithData:] + 89

The encoding works fine, as encodedUser is a valid instance of NSData (NSConcreteMutableData, to be precise).

Is this some sort of interoperability bug of Cocoa API in swift or am I implementing the NSCoding protocol wrong?

回答1:

As Martin pointed out the in the comments, the code works fine in a compiled app, so it's definitely a playground bug.

David, in the comments, suggested to use @objc(User) in order to get a non-mangled class name, but it didn't help in this specific case, so - as of beta 2 - I still haven't find a workaround to make it work in the playground.