iOS app exception的解决方案

最近项目中总是碰到libsystem_kernel.dylib`__pthread_kill + 8, stop reason = signal SIGABRT

类似于这样的错误，但是出现这样的错误之后总是无法定位问题具体的位置。

(lldb) bt

* thread #1: tid = 0x2403, 0x31c16350 libsystem_kernel.dylib`__pthread_kill + 8, stop reason = signal SIGABRT

    frame #0: 0x31c16350 libsystem_kernel.dylib`__pthread_kill + 8

    frame #1: 0x34fa5122 libsystem_c.dylib`pthread_kill + 58

    frame #2: 0x34fe1972 libsystem_c.dylib`abort + 94

    frame #3: 0x38101d4e libc++abi.dylib`abort_message + 74

    frame #4: 0x380ff0da libc++abi.dylib`safe_handler_caller(void (*)()) + 174

    frame #5: 0x380ff114 libc++abi.dylib`std::terminate() + 20

    frame #6: 0x38100598 libc++abi.dylib`__cxa_rethrow + 88

    frame #7: 0x33e0f9d0 libobjc.A.dylib`objc_exception_rethrow + 12

    frame #8: 0x39e66f20 CoreFoundation`CFRunLoopRunSpecific + 456

    frame #9: 0x39e66d48 CoreFoundation`CFRunLoopRunInMode + 104

    frame #10: 0x382342ea GraphicsServices`GSEventRunModal + 74

    frame #11: 0x330a62f8 UIKit`UIApplicationMain + 1120

    frame #12: 0x0001174c XingVelo3`main + 152 at main.m:16

方法一

通过在Xcode的控制台里面打印具体的值

主要命令是bt 或者thread backtrace

1. If you're using gdb, use bt to print the backtrace

2. If you're using lldb, use thread backtrace instead

出现错误之后把信息打印出来，然后追踪具体的位置。但是仅仅这样还不够，很多信息看不到。

方法二，设置exception breakpoint

这个方法可以直接定位到出错的位置，非常强大，也是最近才发现的。

添加exception break point的方法，下面是说明。

If you're running your app out of Xcode, add an exception breakpoint. In the breakpoint navigator (command-6) hit the '+' at the very bottom left to add. This will pause execution on the line that throws the exception and allow you to inspect the current scope, stack, etc.