ios - 无法确定 EXC_BAD_ACCESS 的可能原因(在应用程序启动期间发生)

Question

我在应用商店的应用程序中看到很多崩溃，我完全无法重现或从代码审查中推测可能是什么原因。特别令人困惑的是，这是在应用程序启动时发生的，而内存不足 - 令人困惑是因为如果没有足够的内存供应用程序启动，我可能希望看到其他类型的崩溃报告而不是 EXC_BAD_ACCESS - 即如果 EXC_BAD_ACCESS是由访问已删除的内存引起的，代码中没有任何地方有机会被删除，因为崩溃是在对象正在创建的过程中发生的。

我已经尝试了很多方法来重现这一点——在模拟器中运行并发送低内存警告消息，在应用程序创建过程中故意使各种对象的初始化失败，在应用程序启动期间调用 calloc 以消耗大量内存，运行该应用程序在 RAM 已完全用尽的手机上多次运行。我无法重新创建，也无法从代码检查中看出可能出了什么问题。

这是一个崩溃报告:

Exception Type:  EXC_BAD_ACCESS (SIGSEGV) Exception Subtype:
KERN_INVALID_ADDRESS at 0x0000000000000000 **(many also at 0x0000000000000008)**
Thread 0 name:  Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0  The_Name_Of_MyApp             0x000000010268ca94 SearchViewController.init(coder:) + 838292 (SearchViewController.swift:67)
1  The_Name_Of_MyApp             0x000000010268ca88 SearchViewController.init(coder:) + 838280 (SearchViewController.swift:67)
2  The_Name_Of_MyApp             0x000000010268cd4c @objc SearchViewController.init(coder:) + 838988 (SearchViewController.swift:0)
3  UIKitCore                     0x00000001bca63d64 -[UIClassSwapper initWithCoder:] + 248
4  UIFoundation                  0x000000019a77fe88 UINibDecoderDecodeObjectForValue + 744
5  UIFoundation                  0x000000019a7800cc UINibDecoderDecodeObjectForValue + 1324
6  UIFoundation                  0x000000019a71eb3c -[UINibDecoder decodeObjectForKey:] + 320
7  UIKitCore                     0x00000001bd0a1288 -[UIViewController initWithCoder:] + 1420
8  UIKitCore                     0x00000001bceb5dcc -[UITabBarController initWithCoder:] + 80
9  The_Name_Of_MyApp             0x000000010283f658 TabBarViewController.init(coder:) + 2618968 (TabBarViewController.swift:0)
10 The_Name_Of_MyApp             0x000000010283f70c @objc TabBarViewController.init(coder:) + 2619148 (TabBarViewController.swift:0) 
11 UIKitCore                     0x00000001bca63d64 -[UIClassSwapper initWithCoder:] + 248 
12 UIFoundation                  0x000000019a77fe88 UINibDecoderDecodeObjectForValue + 744 
13 UIFoundation                  0x000000019a71eb3c -[UINibDecoder decodeObjectForKey:] + 320 
14 UIKitCore                     0x00000001bcd9dcbc -[UIRuntimeConnection initWithCoder:] + 188 
15 UIFoundation                  0x000000019a77fe88 UINibDecoderDecodeObjectForValue + 744 
16 UIFoundation                  0x000000019a7800cc UINibDecoderDecodeObjectForValue + 1324 
17 UIFoundation                  0x000000019a71eb3c -[UINibDecoder decodeObjectForKey:] + 320 
18 UIKitCore                     0x00000001bccc4a1c -[UINib instantiateWithOwner:options:] + 1124 
19 UIKitCore                     0x00000001bce92f18 -[UIStoryboard instantiateViewControllerWithIdentifier:] + 196 
20 The_Name_Of_MyApp             0x000000010266b4dc InitialViewController.start() + 701660 (InitialViewController.swift:118) 
21 The_Name_Of_MyApp             0x000000010266bba4 @objc InitialViewController.start() + 703396 (InitialViewController.swift:0) 
22 Foundation                    0x0000000190bff6d0 __NSFireDelayedPerform + 404 
23 CoreFoundation                0x00000001900f2bf0 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 28 
24 CoreFoundation                0x00000001900f2920 __CFRunLoopDoTimer +864 
25 CoreFoundation                0x00000001900f2154 __CFRunLoopDoTimers + 248 
26 CoreFoundation                0x00000001900ed030 __CFRunLoopRun + 1880 
27 CoreFoundation                0x00000001900ec5b8 CFRunLoopRunSpecific + 436 
28 GraphicsServices              0x0000000192360584 GSEventRunModal + 100 
29 UIKitCore                     0x00000001bc9e3558 UIApplicationMain + 212 
30 The_Name_Of_MyApp             0x00000001026ea6b0 main + 1222320 (AppDelegate.swift:20) 
31 libdyld.dylib                 0x000000018fbacb94 start + 4

Thread 1: 
0  libsystem_pthread.dylib       0x000000018fd80cfc start_wqthread + 0

Thread 2 name:  Dispatch queue: com.myQueue.backgroundSerialQueue
Thread 2: 
0  libsystem_c.dylib             0x000000018fc60ae4 __v2printf + 616 
1  libsystem_c.dylib             0x000000018fc60a00 __v2printf + 388 
2  libsystem_c.dylib             0x000000018fc46ac0 _vsnprintf + 264 
3  libsystem_c.dylib             0x000000018fc3b9c0 snprintf_l + 28 
4  CoreFoundation                0x000000019010fa88 __CFStringAppendFormatCore + 8548 
5  CoreFoundation                0x00000001901111b8 _CFStringCreateWithFormatAndArgumentsAux2 + 136 
6  Foundation                    0x0000000190afd3ec -[NSString initWithFormat:locale:] + 36 
7  Foundation                    0x0000000190afd364 -[NSNumber descriptionWithLocale:] + 1044 
8  CoreFoundation                0x000000019004d9a8 -[__NSCFNumber descriptionWithLocale:] + 72 
9  CoreFoundation                0x0000000190053268 -[__NSCFNumber stringValue] + 64 
10 The_Name_Of_MyApp             0x00000001025f6494 -[RobocallerManager readCityAndStateData] + 222356 (RobocallerManager.m:596) 
11 The_Name_Of_MyApp             0x00000001025f343c __25-[RobocallerManager init]_block_invoke + 209980 (RobocallerManager.m:148) 
12 libdispatch.dylib             0x000000018fb9b6c8 _dispatch_call_block_and_release + 24 
13 libdispatch.dylib             0x000000018fb9c484 _dispatch_client_callout + 16 
14 libdispatch.dylib             0x000000018fb43c18 _dispatch_lane_serial_drain$VARIANT$mp + 592 
15 libdispatch.dylib             0x000000018fb44760 _dispatch_lane_invoke$VARIANT$mp + 432 
16 libdispatch.dylib             0x000000018fb4cf00 _dispatch_workloop_worker_thread + 600 
17 libsystem_pthread.dylib       0x000000018fd7e0f0 _pthread_wqthread + 312 
18 libsystem_pthread.dylib       0x000000018fd80d00 start_wqthread + 4

Thread 3: 
0  libsystem_pthread.dylib       0x000000018fd80cfc start_wqthread + 0

Thread 4 name:  com.apple.uikit.eventfetch-thread
Thread 4: 
0  libsystem_kernel.dylib        0x000000018fceded0 mach_msg_trap + 8 
1  libsystem_kernel.dylib        0x000000018fced3a8 mach_msg + 72 
2  CoreFoundation                0x00000001900f1fb0 __CFRunLoopServiceMachPort + 236 
3  CoreFoundation                0x00000001900ece4c __CFRunLoopRun + 1396 
4  CoreFoundation                0x00000001900ec5b8 CFRunLoopRunSpecific + 436 
5  Foundation                    0x0000000190ae06a4 -[NSRunLoop+ 34468 (NSRunLoop) runMode:beforeDate:] + 300 
6  Foundation                    0x0000000190ae0514 -[NSRunLoop+ 34068 (NSRunLoop) runUntilDate:] + 88 
7  UIKitCore                     0x00000001bc940ac0 -[UIEventFetcher threadMain] + 136 
8  Foundation                    0x0000000190c133b0 __NSThread__start__ + 1040 
9  libsystem_pthread.dylib       0x000000018fd7d2fc _pthread_body + 128 
10 libsystem_pthread.dylib       0x000000018fd7d25c _pthread_start + 48 
11 libsystem_pthread.dylib       0x000000018fd80d08 thread_start + 4

Thread 5 name:  com.twitter.crashlytics.ios.MachExceptionServer
Thread 5: 
0  libsystem_kernel.dylib        0x000000018fceded0 mach_msg_trap + 8 
1  libsystem_kernel.dylib        0x000000018fced3a8 mach_msg + 72 
2  The_Name_Of_MyApp             0x000000010288d08c CLSMachExceptionServer + 1180 
3  libsystem_pthread.dylib       0x000000018fd7d2fc _pthread_body + 128 
4  libsystem_pthread.dylib       0x000000018fd7d25c _pthread_start + 48 
5  libsystem_pthread.dylib       0x000000018fd80d08 thread_start + 4

Thread 6: 
0  libsystem_pthread.dylib       0x000000018fd80cfc start_wqthread + 0

Thread 7: 
0  libsystem_pthread.dylib       0x000000018fd80cfc start_wqthread + 0

Thread 8: 
0  libsystem_pthread.dylib       0x000000018fd80cfc start_wqthread + 0

Thread 9: 
0  libsystem_pthread.dylib       0x000000018fd80cfc start_wqthread + 0

Thread 10 name:  com.apple.NSURLConnectionLoader
Thread 10: 
0  libsystem_kernel.dylib        0x000000018fceded0 mach_msg_trap + 8 
1  libsystem_kernel.dylib        0x000000018fced3a8 mach_msg + 72 
2  CoreFoundation                0x00000001900f1fb0 __CFRunLoopServiceMachPort + 236 
3  CoreFoundation                0x00000001900ece4c __CFRunLoopRun + 1396 
4  CoreFoundation                0x00000001900ec5b8 CFRunLoopRunSpecific + 436 
5  CFNetwork                     0x000000019070ce18 -[__CoreSchedulingSetRunnable runForever] + 212 
6  Foundation                    0x0000000190c133b0 __NSThread__start__ + 1040 
7  libsystem_pthread.dylib       0x000000018fd7d2fc _pthread_body + 128 
8  libsystem_pthread.dylib       0x000000018fd7d25c _pthread_start + 48 
9  libsystem_pthread.dylib       0x000000018fd80d08 thread_start + 4

Thread 0 crashed with ARM Thread State (64-bit):
    x0: 0x0000000000000000   x1: 0x0000000000000000   x2: 0x0000000282718580   x3: 0x0000000000000000
    x4: 0x0000000104870680   x5: 0x0000000000000000   x6: 0x0000000000000072   x7: 0x00000000000000a0
    x8: 0x0000000103f03650   x9: 0x0000000000000000  x10: 0x000000000000001f  x11: 0x0000000000000005
    x12: 0x0000000000000005  x13: 0x0000000000000000  x14: 0x0000000000000068  x15: 0x00000001ae696425
    x16: 0x000000018f34b858  x17: 0x0000000102601328  x18: 0x0000000000000000  x19: 0x0000000104853200
    x20: 0x00000001048709c8  x21: 0x0000000280b73880  x22: 0x00000001c92684c0  x23: 0x0000000104870600
    x24: 0x0000000281e51ec0  x25: 0x00000001c73e2000  x26: 0x0000000000000002  x27: 0x00000001c73e2000  
    x28: 0x0000000000000171   fp: 0x000000016d83c0b0   lr: 0x000000010268ca88
    sp: 0x000000016d83bcc0   pc: 0x000000010268ca94 cpsr: 0x60000000

下图概述了崩溃报告中显示的对象之间的关系。基本上在应用程序启动时，AppDelegate 会导致 LicenceManger 对象被实例化，这反过来会导致创建 DatabaseManager 和 Database 对象，所有这些都是模型类型类。同时，GUI 正在启动，InitialVC 是一个根 VC，它实例化一个 TabBar VC，这导致 SearchVC 的实例化。SearchVC 访问 DatabaseModel 对象，这就是崩溃发生的地方。

这里是代码(简化为相关部分，注意代码是 Swift 除了 DataBaseManager 是 Ojb-C)

初始 View Controller

////////////////// InitialViewController ////////////////////////////
class InitialViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        self.perform(#selector(InitialViewController.start), with: nil, afterDelay: 1.5)
    }
}

@objc func start() {
    let tbvc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "TabBarViewControllerID") as! TabBarViewController
navigationController.pushViewController(tbvc, animated: true)
}

SearchViewController 是由于它与 TabBarViewControllerSp 之间存在关系而创建的

搜索 View Controller

///////////////////////// SearchViewController ///////////////////////////////
class SearchViewController: UITableViewController, UISearchBarDelegate {
    var searchResultsList   = DatabaseManager.instance().database.emptyList() /** line 67 **/

应用代理

////////////////////// App Delegate ///////////////////////////
AppDelegate:didFinishLaunchingWithOptions() {
    let _ = LicenseManager.instance
}

许可证管理器

//////////////////////// LicenseManager ////////////////////////
@objc class LicenseManager : NSObject {
    @objc open static let instance = LicenseManager()
    private let databaseManager = DatabaseManager.instance()
}

override private init() {
    super.init()
}

数据库管理器

///////////////////// DatabaseManager ////////////////////////
+ (DatabaseManager*) instance {
    static DatabaseManager *theInstance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^ {
        theInstance = [[DatabaseManager alloc] init];
    });
    return theInstance;
}

@interface DatabaseManager()
@property (strong, nonatomic)   Database*  _Nonnull database;
@property (strong, nonatomic)   NSMutableDictionary* cityAndStateDictionary;
@end


@implementation DatabaseManager
- (id) init {
    self = [super init];
    if (self)
    {
        _database   = Database.instance;
        [_database openOrCreateDatabase];


        dispatch_async(robocallerQueue(), ^{
            [self readCityAndStateData];
        });
    }
    return self;
}


//Populates a very large dictionary > 100K entries
- (void) readCityAndStateData
{
    NSBundle* bundle = [NSBundle bundleForClass:[DatabaseManager class]];
    NSString *filePath = [bundle pathForResource:@"CityState" ofType:@"json"];
    NSData *data = [NSData dataWithContentsOfFile:filePath];
    Assert(data, @"unable to read CityState.json file");

    NSError* __autoreleasing  nserror;
    NSDictionary* jsonParser = [NSJSONSerialization JSONObjectWithData: data
                                                               options: NSJSONReadingAllowFragments
                                                                 error: &nserror];
    if (nserror == nil)
    {
        self.cityAndStateDictionary = [[NSMutableDictionary alloc] init];
        self.stateDictionary = [[NSMutableDictionary alloc] init];
        for (NSDictionary *item in jsonParser)
        {
            NSNumber* num1  = item[@"Code1"];
            NSNumber* num2  = item[@"Code2"];
            NSString* key   = [NSString stringWithFormat:@"%@%@", num1.stringValue, num2.stringValue];
            NSString* city  = item[@"City"];
            NSString* state = item[@"State"];
            NSString* value = [NSString stringWithFormat:@"%@, %@", [city capitalizedString], state];
            (self.cityAndStateDictionary)[key] = value;

            NSString* stateKey = [num1 stringValue];
            (self.stateDictionary)[stateKey] = state;
        }
        self.cityAndStateDataLoaded = TRUE;
    }
    else
    {
        Assert(data, @"unable to parse CityState.json file");
    }
}

数据库

////////////////////// Database //////////////////////
@objcMembers class Database : NSObject {
    open static let instance = Database()
    fileprivate var configuration:Realm.Configuration?    = nil

    override init()
    {
    }
}


@objc func openOrCreateDatabase() {
       configuration = Realm.Configuration(encryptionKey: Database.getKey() as Data)
}

class func getKey() -> NSData {
    let string = "AED16D8B-7762-4CBF-A313-48FDCAD51B9C23456754635498123450ka&9dB6t"
    let data = string.data(using: String.Encoding.utf8)
    return data! as NSData
}

func emptyList() -> Results<Caller> {        
    let realm = try! Realm(configuration: configuration!)
    let mdn = "DoesNotExist"
    let searchTerm = "number ==  " + "\"" + mdn + "\""
    let results = realm.objects(Caller.self).filter(searchTerm)
    return results
 }

来电者

//////////////// Caller ///////////
@objc public class Caller : Object {
    @objc dynamic var name:String? = nil
    // More simple types, strings, dates, ints etc.
}

Answer 1

僵尸

这不是强制解包的结果，我猜这是故意的，如果无法创建数据库会故意崩溃。 EXC_BAD_ACCESS KERN_INVALID_ADDRESS当你有一个僵尸时发生:代码试图访问释放的内存(类似的崩溃消息 here 和 here )。

以下是消除僵尸的一般建议:

• 在您方案的“诊断”选项卡中启用 Xcode 中的僵尸对象
• 使用 Instruments 在您的项目中寻找僵尸

---

第67行

罪魁祸首是:DatabaseManager.instance().database.emptyList()

1. DatabaseManager.instance()

   这是首先在 AppDelegate 中通过 let _ = LicenseManager.instance 创建的.由于应用程序在调用 SearchViewController.init(coder:) 时崩溃，而不是在 AppDelegate 中，可以公平地假设创建 DatabaseManager.instance() , Database.instance在 AppDelegate 中是无害的。

2. DatabaseManager.instance().database

   这也不是罪魁祸首，如前所述:这是在 AppDelegate 中创建的。

3. emptyList()

   这给我们留下了这个方法。它在主线程中被调用。作为一种方法本身，它会以 KERN_INVALID_ADDRESS 使应用程序崩溃的唯一情况。消息，如果它被发送到僵尸。这意味着 DatabaseManager.instance().database在主线程中还不存在。这意味着 1.5 InitialViewController 中的第二次延迟不够 robocallerQueue返回一个非零 DatabaseManager.instance().database .从崩溃报告可以看到，当主线程(线程0)崩溃时，线程2还在执行readCityAndStateData .

---

解决方案

我建议标记 searchResultsList懒惰，或使用完成处理程序而不是 1.5 秒延迟。