构建时的 Segfault 代码 11 可能是由 Swift 项目中的 Objective-C Singleton 引起的

Posted 2023-02-25

【中文标题】构建时的 Segfault 代码 11 可能是由 Swift 项目中的 Objective-C Singleton 引起的

【英文标题】：Segfault code 11 at build time probably caused by Objective-C Singleton in Swift project

【发布时间】：2016-04-09 09:59:57

【问题描述】：

我正在制作一个播放音频文件的 Swift ios 应用，并且为此使用了 The Amazing Audio Engine 2 库。

我决定使用单例模式来管理这个任务。在他的 Swift 示例项目中，lib 的创建者 Michael Tyson 在 Objective-C 中完成了他的音频部分（如果我理解的话，用于具有 C 函数的内存管理内容）。 你可以在这里找到他的解释视频：https://www.youtube.com/watch?v=OZQT4IGS8mA 所以我跟随他的脚步，用 Objective-C 编写了我的 Singleton。

这是我的代码：

AudioManager.h

#import <Foundation/Foundation.h>
#import "TheAmazingAudioEngine/TheAmazingAudioEngine.h"

@class Track;

@interface AudioManager : NSObject 
    NSString *test;


@property (nonatomic, strong) AEAudioUnitOutput  *_Nonnull output;
@property (nonatomic, strong) AERenderer *_Nonnull renderer;
@property (nonatomic, strong) AEAudioFilePlayerModule *_Nullable currentTrackModule;
@property (nonatomic) BOOL recording;
@property (nonatomic) Track *_Nullable currentTrack;

+ (_Nonnull id)defaultAudioManager;
- (BOOL)startAudioController:(NSError *_Nullable *_Nullable)error;
- (void)stopAudioController;
- (void)prepareTrackModule;
- (void)playCurrentTrack:(BOOL)loop;

@end

AudioManager.m

#import "AudioManager.h"
#import "Project-Swift.h"
@import AVFoundation;

@implementation AudioManager

//@synthesize someProperty;

#pragma mark Singleton Methods

+ (id)defaultAudioManager 
    static AudioManager *defaultAudioManager = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^
        defaultAudioManager = [[self alloc] init];
    );
    return defaultAudioManager;


- (id)init 
    if ( !(self = [super init]) ) return nil;
    //someProperty = @"Default Property Value";
    self.renderer = [AERenderer new];
    self.output = [[AEAudioUnitOutput alloc] initWithRenderer:self.renderer];

    return self;


- (void)dealloc 
    // Should never be called, but just here for clarity really.


- (BOOL)startAudioController:(NSError * _Nullable * _Nullable)error 
    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayAndRecord error:NULL];

    return [self.output start:error];


- (void)stopAudioController 
    return [self.output stop];


- (void)prepareTrackModule 
    self.currentTrackModule = [[AEAudioFilePlayerModule alloc] initWithRenderer:self.renderer
                                                  URL:[[NSBundle mainBundle]
                                                       URLForResource:@"amen"//self.currentTrack.name
                                                       withExtension:@"m4a"]
                                                error:NULL];


- (void)playCurrentTrack:(BOOL)loop 
    self.currentTrackModule.loop = loop;
    [self.currentTrackModule playAtTime:0];
    __unsafe_unretained typeof(self) weakSelf = self;
    self.renderer.block = ^(const AERenderContext *context) 
        AEModuleProcess(weakSelf.currentTrackModule, context);

        AEBufferStackMixToBufferList(context->stack, 1, 0, YES, context->output);
    ;


@end

AppDelegate.Swift

import UIKit
import CoreData

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate 

    var window: UIWindow?

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool 
        // Override point for customization after application launch.

        do 
            try AudioManager.defaultAudioManager().startAudioController()
            //AudioManager.defaultAudioManager().prepareTrackModule()
            //AudioManager.defaultAudioManager().playCurrentTrack(true)
         catch 
            //Handle Error
            print("error")
        

        return true
    

    func applicationWillResignActive(application: UIApplication) 
        // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
        // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
    

    func applicationDidEnterBackground(application: UIApplication) 
        // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
        // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
    

    func applicationWillEnterForeground(application: UIApplication) 
        // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
    

    func applicationDidBecomeActive(application: UIApplication) 
        // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
    

    func applicationWillTerminate(application: UIApplication) 
        // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
        // Saves changes in the application's managed object context before the application terminates.
        self.saveContext()
    

如果我在我的AppDelegate.swift 文件中注释try AudioManager.defaultAudioManager().startAudioController() 行，显然一切正常，否则，当我尝试编译时，Xcode 会打印出这个非常有用的错误：

0  swift                    0x000000010411d4eb llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 43
1  swift                    0x000000010411c7d6 llvm::sys::RunSignalHandlers() + 70
2  swift                    0x000000010411db4f SignalHandler(int) + 287
3  libsystem_platform.dylib 0x00007fff9a64352a _sigtramp + 26
4  libsystem_platform.dylib 0x0000000000000001 _sigtramp + 1704708849
5  swift                    0x0000000101fba410 (anonymous namespace)::IRGenSILFunction::visitFullApplySite(swift::FullApplySite) + 2736
6  swift                    0x0000000101fa7c4b swift::irgen::IRGenModule::emitSILFunction(swift::SILFunction*) + 9787
7  swift                    0x0000000101f02fd8 swift::irgen::IRGenModuleDispatcher::emitGlobalTopLevel() + 600
8  swift                    0x0000000101f8ea5e performIRGeneration(swift::IRGenOptions&, swift::ModuleDecl*, swift::SILModule*, llvm::StringRef, llvm::LLVMContext&, swift::SourceFile*, unsigned int) + 1278
9  swift                    0x0000000101f8ef06 swift::performIRGeneration(swift::IRGenOptions&, swift::SourceFile&, swift::SILModule*, llvm::StringRef, llvm::LLVMContext&, unsigned int) + 70
10 swift                    0x0000000101e72a1c performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&) + 15004
11 swift                    0x0000000101e6e41d frontend_main(llvm::ArrayRef<char const*>, char const*, void*) + 2781
12 swift                    0x0000000101e69e3c main + 1932
13 libdyld.dylib            0x00007fff996215ad start + 1
14 libdyld.dylib            0x00000000000000bc start + 1721625360
Stack dump:

Command failed due to signal: Segmentation fault: 11

我认为我在 Objective-C 部分中遗漏了一些我不理解的东西，我对这种语言不是很熟悉，但我不知道是什么。 有什么想法吗？

【问题讨论】：

在 startAudiocontroller func 中，它接受一个 NSError 参数并且您没有向它传递任何值。尽管它可以为空，但 swift 不能很好地处理空值，并且必须使用 if let 或 guard 进行显式处理。尝试解决 NSError 部分，看看是否能解决问题。

@ArunGupta 我不确定我必须做什么，如果没有 Xcode 打印错误 Cannot call value of non-function type '(() throws -> ())!'，我无法将任何参数传递给 appDelegate.swift 中的 startAudioController

【参考方案1】：

其实如果我去掉startAudioController函数的参数，segfault就消失了。我不知道究竟是为什么，但这可能是一个临时解决方案