How to analyze iPhone's device log? - iphone

Question

Can anyone tell me how to analyse the iPhone's device log?
In addition, can anyone explain what the following means?
0 libobjc.A.dylib 0x00007dd2 prepareForMethodLookup + 10",
Thread 0 Crashed:
0 libobjc.A.dylib 0x00007dd2 prepareForMethodLookup + 10
1 libobjc.A.dylib 0x00005162 lookUpMethod + 34
2 libobjc.A.dylib 0x0000290e _class_lookupMethodAndLoadCache + 6
3 libobjc.A.dylib 0x00002644 objc_msgSend_uncached + 20
4 iPad4HB 0x0002f112 0x1000 + 188690
5 iPad4HB 0x00010c86 0x1000 + 64646
6 CoreFoundation 0x00025166 -[NSObject performSelector:withObject:withObject:] + 18
7 UIKit 0x00055166 -[UIApplication sendAction:to:from:forEvent:] + 78
8 UIKit 0x00055106 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 26
9 UIKit 0x000550d8 -[UIControl sendAction:to:forEvent:] + 32
10 UIKit 0x00054e2a -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 350
11 UIKit 0x0019a4f2 -[UISlider endTrackingWithTouch:withEvent:] + 166
12 UIKit 0x00055444 -[UIControl touchesEnded:withEvent:] + 284
13 UIKit 0x00053e4e -[UIWindow _sendTouchesForEvent:] + 322
14 UIKit 0x00053796 -[UIWindow sendEvent:] + 74
15 UIKit 0x0004f3b8 -[UIApplication sendEvent:] + 260
16 UIKit 0x0004ed24 _UIApplicationHandleEvent + 4772
17 GraphicsServices 0x00003b2c PurpleEventCallback + 660
18 CoreFoundation 0x00022d96 CFRunLoopRunSpecific + 2214
19 CoreFoundation 0x000224da CFRunLoopRunInMode + 42
20 GraphicsServices 0x000030d4 GSEventRunModal + 108
21 GraphicsServices 0x00003180 GSEventRun + 56
22 UIKit 0x000034c2 -[UIApplication _run] + 374
23 UIKit 0x000019ec UIApplicationMain + 636
24 iPad4HB 0x00002d68 0x1000 + 7528
25 iPad4HB 0x00002d1c 0x1000 + 7452

Answer 1

What you are looking at is a stack trace. It shows all function and method calls that your application made in a specific thread. Up to the point where it crashed.
The first line ('distance' 0) is the most recent location. So this is the place where the application most likely crashed.
The last line ('distance' 25) is the start of the application.
The libobjc.A.dylib is the place where the application crashed. This can show libraries (libobjc.A.dylib) , frameworks (UIKit) and your application (iPad4HB).
The hexadecimal number (0x00007dd2) is the memory location of that specific function or method.
The next column shows the actual function or method name. Where prepareForMethodLookup is a plain C function while -[NSObject performSelector:withObject:] is a method.
The '+ 10' is an indication of where in the function or method the call to the next method or function was made. It is an offset into the compiled code of the function, so this number is mostly meaningless.
However, if you kept your .dSYM file, then you can convert the number to a real line number in a specific file.
See for example http://www.anoshkin.net/blog/2008/09/09/iphone-crash-logs/