目录
文件准备与验证
符号化需要有dSYM（符号表）文件，crash文件。
我们创建一个Person类，在.h文件内声明-(void)test;方法，但并不实现。
执行下面代码
Person * person = [[Person alloc] init];
[person test];
将测试demo编译运行安装到手机，在相应目录下取出dSYM文件保存。
手机在非调试状态下运行demo，才会生成crash文件，然后导出crash文件。
执行指令查看dSYM文件的UUID
xcrun dwarfdump --uuid iOSTest.app.dSYM
UUID: C9C138E6-4CF7-3790-9D07-BD44682717E1 (armv7) iOSTest.app.dSYM/Contents/Resources/DWARF/iOSTest
UUID: F1915EB2-AEE0-3EDD-AE99-08F7997CDF77 (arm64) iOSTest.app.dSYM/Contents/Resources/DWARF/iOSTest
执行指令查看crash文件的UUID
grep --after-context=2 "Binary Images:" iOSTest.crash
Binary Images:
0x100084000 - 0x10008bfff iOSTest arm64 <f1915eb2aee03eddae9908f7997cdf77> /var/mobile/Containers/Bundle/Application/48885D93-C3A2-4CAA-BC40-812E7307DECA/iOSTest.app/iOSTest
可以看到arm64架构下
dSYM文件的UUID ：F1915EB2-AEE0-3EDD-AE99-08F7997CDF77
crash文件的UUID：f1915eb2aee03eddae9908f7997cdf77
对比一致，也就是说crash文件能够通过dSYM将地址信息符号化。
符号化
crash文件线程回溯部分信息如下
Last Exception Backtrace:
0 CoreFoundation 0x181a75900 __exceptionPreprocess + 124
1 libobjc.A.dylib 0x1810e3f80 objc_exception_throw + 55
2 CoreFoundation 0x181a7c61c -[NSObject+ 1230364 (NSObject) doesNotRecognizeSelector:] + 211
3 CoreFoundation 0x181a795b8 ___forwarding___ + 871
4 CoreFoundation 0x18197d68c _CF_forwarding_prep_0 + 91
5 iOSTest 0x100089170 0x100084000 + 20848
6 UIKit 0x1867680c0 -[UIViewController loadViewIfRequired] + 995
7 UIKit 0x186767cc4 -[UIViewController view] + 27
8 UIKit 0x18676eab4 -[UIWindow addRootViewControllerViewIfPossible] + 75
9 UIKit 0x18676bfa0 -[UIWindow _setHidden:forced:] + 251
10 UIKit 0x1867e1cd0 -[UIWindow makeKeyAndVisible] + 47
11 UIKit 0x186a0c358 -[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 3455
12 UIKit 0x186a104b8 -[UIApplication _runWithMainScene:transitionContext:completion:] + 1671
13 UIKit 0x186a0d5c0 -[UIApplication workspaceDidEndTransaction:] + 167
14 FrontBoardServices 0x18302b790 -[FBSSerialQueue _performNext] + 183
15 FrontBoardServices 0x18302bb10 -[FBSSerialQueue _performNextFromRunLoopSource] + 55
16 CoreFoundation 0x181a2cefc __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 23
17 CoreFoundation 0x181a2c990 __CFRunLoopDoSources0 + 539
18 CoreFoundation 0x181a2a690 __CFRunLoopRun + 723
19 CoreFoundation 0x181959680 CFRunLoopRunSpecific + 383
20 UIKit 0x1867d6580 -[UIApplication _run] + 459
21 UIKit 0x1867d0d90 UIApplicationMain + 203
22 iOSTest 0x100089c84 0x100084000 + 23684
23 libdyld.dylib 0x1814fa8b8 start + 3
可以看出行号5、行号22的堆栈信息并不能看出具体是哪里出现问题。
| 帧编号 数字越小，发生时间越晚 |
二进制库的名称 | 调用方法的地址 | 基本地址+偏移量 调用方法地址=基本地址+偏移量 |
| 5 | iOSTest | 0x100089170 | 0x100084000 + 20848 |
| 22 | iOSTest | 0x100089c84 | 0x100084000 + 23684 |
应用崩溃发生在运行时地址0x100089170，该进程的运行时起始地址是0x100084000，崩溃处距离进程起始地址的偏移量为十进制的20848(对应十六进制为0x5170)。三者对应关系：
0x100089170 = 0x100084000 + 0x5170
崩溃堆栈中的起始地址和崩溃地址均为运行时地址，根据虚拟内存偏移量不变原理，只要提供了符号表TEXT段的起始地址，再加上偏移量（这里为0x5170）就能得到符号表中的堆栈地址，即：
符号表堆栈地址 = 符号表起始地址 + 偏移量
atos简单使用
开发者从crash文件能获取到错误堆栈信息，而使用atos工具就是把地址对应的具体符号信息找到。
它是一个可以把地址转换为函数名（包括行号）的工具。
atos无需计算崩溃地址对应的符号表地址的方式，命令格式如下：
atos -o Your.app.dSYM/Contents/Resources/DWARF/Your -arch armv7 -l 进程起始地址 崩溃发生在运行时地址
帧编号5栈信息中地址符号化：
atos -o iOSTest.app.dSYM/Contents/Resources/DWARF/iOSTest -arch arm64 -l 0x100084000 0x100089170
-[ViewController viewDidLoad] (in iOSTest) (ViewController.mm:65)
帧编号22栈信息中地址符号化：
//可以进入到 iOSTest.app.dSYM/Contents/Resources/DWARF 目录下
atos -o iOSTest -arch arm64 -l 0x100084000 0x100089c84
main (in iOSTest) (main.m:20)
symbolicatecrash使用
symbolicatecrash是Xcode自带的一个分析工具，可以通过机器上的崩溃日志和应用的.dSYM文件定位发生崩溃的位置，把crash日志中的一堆地址替换成代码相应位置
1、在你的MAC桌面创建一个新文件夹，并且命名为”CrashReport”
2、查看symbolicatecrash文件路径：
打开终端输入：find /Applications/Xcode.app -name symbolicatecrash -type f
find /Applications/Xcode.app -name symbolicatecrash -type f
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/iOSSupport/Library/PrivateFrameworks/DVTFoundation.framework/Versions/A/Resources/symbolicatecrash
/Applications/Xcode.app/Contents/Developer/Platforms/WatchSimulator.platform/Developer/Library/PrivateFrameworks/DVTFoundation.framework/symbolicatecrash
/Applications/Xcode.app/Contents/Developer/Platforms/AppleTVSimulator.platform/Developer/Library/PrivateFrameworks/DVTFoundation.framework/symbolicatecrash
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/Library/PrivateFrameworks/DVTFoundation.framework/symbolicatecrash
/Applications/Xcode.app/Contents/SharedFrameworks/DVTFoundation.framework/Versions/A/Resources/symbolicatecrash
文件路径是：/Applications/Xcode.app/Contents/SharedFrameworks/DVTFoundation.framework/Versions/A/Resources/symbolicatecrash
将symbolicatecrash拷贝到CrashReport文件夹
3、将dSYM文件与crash文件拷贝到CrashReport文件夹
4、依次执行下面指令生成iOSTestSymbol.crash
cd /Users/username/Desktop/CrashReport
export DEVELOPER_DIR=/Applications/XCode.app/Contents/Developer
./symbolicatecrash ./iOSTest.crash ./iOSTest.app.dSYM > iOSTestSymbol.crash
看下iOSTestSymbol.crash文件内线程回溯部分
Last Exception Backtrace:
0 CoreFoundation 0x181a75900 __exceptionPreprocess + 124
1 libobjc.A.dylib 0x1810e3f80 objc_exception_throw + 55
2 CoreFoundation 0x181a7c61c -[NSObject+ 1230364 (NSObject) doesNotRecognizeSelector:] + 211
3 CoreFoundation 0x181a795b8 ___forwarding___ + 871
4 CoreFoundation 0x18197d68c _CF_forwarding_prep_0 + 91
5 iOSTest 0x100089170 -[ViewController viewDidLoad] + 20848 (ViewController.mm:65)
6 UIKit 0x1867680c0 -[UIViewController loadViewIfRequired] + 995
7 UIKit 0x186767cc4 -[UIViewController view] + 27
8 UIKit 0x18676eab4 -[UIWindow addRootViewControllerViewIfPossible] + 75
9 UIKit 0x18676bfa0 -[UIWindow _setHidden:forced:] + 251
10 UIKit 0x1867e1cd0 -[UIWindow makeKeyAndVisible] + 47
11 UIKit 0x186a0c358 -[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 3455
12 UIKit 0x186a104b8 -[UIApplication _runWithMainScene:transitionContext:completion:] + 1671
13 UIKit 0x186a0d5c0 -[UIApplication workspaceDidEndTransaction:] + 167
14 FrontBoardServices 0x18302b790 -[FBSSerialQueue _performNext] + 183
15 FrontBoardServices 0x18302bb10 -[FBSSerialQueue _performNextFromRunLoopSource] + 55
16 CoreFoundation 0x181a2cefc __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 23
17 CoreFoundation 0x181a2c990 __CFRunLoopDoSources0 + 539
18 CoreFoundation 0x181a2a690 __CFRunLoopRun + 723
19 CoreFoundation 0x181959680 CFRunLoopRunSpecific + 383
20 UIKit 0x1867d6580 -[UIApplication _run] + 459
21 UIKit 0x1867d0d90 UIApplicationMain + 203
22 iOSTest 0x100089c84 main + 23684 (main.m:20)
23 libdyld.dylib 0x1814fa8b8 start + 3
发现帧编号5、帧编号22对应的信息已经符号化。
行者常至，为者常成！