在我的iOS App中捕获这样的错误日志，什么原因呢？

2011-04-18 上午10点

Thread 0 Crashed:
0   libobjc.A.dylib                   0x33a06466 objc_msgSend + 18
1   UIKit                             0x313bdffe -[UIApplication _cancelGestureRecognizersForView:] + 18
2   UIKit                             0x313b22e2 -[UIView(Hierarchy) _willMoveToWindow:] + 34
3   CoreFoundation                    0x30435fe6 -[NSObject(NSObject) performSelector:withObject:withObject:] + 18
4   UIKit                             0x3139daba -[UIView(Hierarchy) _makeSubtreePerformSelector:withObject:withObject:copySublayers:] + 170
5   UIKit                             0x3139dace -[UIView(Hierarchy) _makeSubtreePerformSelector:withObject:withObject:copySublayers:] + 190
6   UIKit                             0x3139dace -[UIView(Hierarchy) _makeSubtreePerformSelector:withObject:withObject:copySublayers:] + 190
7   UIKit                             0x3139dace -[UIView(Hierarchy) _makeSubtreePerformSelector:withObject:withObject:copySublayers:] + 190
8   UIKit                             0x3139dace -[UIView(Hierarchy) _makeSubtreePerformSelector:withObject:withObject:copySublayers:] + 190
9   UIKit                             0x3139dace -[UIView(Hierarchy) _makeSubtreePerformSelector:withObject:withObject:copySublayers:] + 190
10  UIKit                             0x3139dace -[UIView(Hierarchy) _makeSubtreePerformSelector:withObject:withObject:copySublayers:] + 190
11  UIKit                             0x3139dace -[UIView(Hierarchy) _makeSubtreePerformSelector:withObject:withObject:copySublayers:] + 190
12  UIKit                             0x3139dace -[UIView(Hierarchy) _makeSubtreePerformSelector:withObject:withObject:copySublayers:] + 190
13  UIKit                             0x313b35a0 -[UIView(Hierarchy) removeFromSuperview] + 208
14  UIKit                             0x31414c5a -[UITransitionView _didCompleteTransition:] + 350
15  UIKit                             0x314146ae -[UITransitionView transition:fromView:toView:] + 662
16  UIKit                             0x314143f4 -[UITransitionView transition:toView:] + 72
17  UIKit                             0x31415f84 -[UITabBarController transitionFromViewController:toViewController:transition:shouldSetSelected:] + 236
18  UIKit                             0x31415e86 -[UITabBarController transitionFromViewController:toViewController:] + 26
19  UIKit                             0x3141572c -[UITabBarController _setSelectedViewController:] + 180
20  UIKit                             0x314dab90 -[UITabBarController setSelectedViewController:] + 8
21  UIKit                             0x314db480 -[UITabBarController _tabBarItemClicked:] + 220
22  CoreFoundation                    0x30435fe6 -[NSObject(NSObject) performSelector:withObject:withObject:] + 18
23  UIKit                             0x313bb4a6 -[UIApplication sendAction:to:from:forEvent:] + 78
24  UIKit                             0x313bb446 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 26
25  UIKit                             0x31586230 -[UITabBar _sendAction:withEvent:] + 264
26  CoreFoundation                    0x30435fe6 -[NSObject(NSObject) performSelector:withObject:withObject:] + 18
27  UIKit                             0x313bb4a6 -[UIApplication sendAction:to:from:forEvent:] + 78
28  UIKit                             0x313bb446 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 26
29  UIKit                             0x313bb418 -[UIControl sendAction:to:forEvent:] + 32
30  UIKit                             0x313bb16a -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 350
31  UIKit                             0x313eeffa -[UIControl sendActionsForControlEvents:] + 10
32  UIKit                             0x31583642 -[UITabBar(Static) _buttonUp:] + 74
33  CoreFoundation                    0x30435fe6 -[NSObject(NSObject) performSelector:withObject:withObject:] + 18
34  UIKit                             0x313bb4a6 -[UIApplication sendAction:to:from:forEvent:] + 78
35  UIKit                             0x313bb446 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 26
36  UIKit                             0x313bb418 -[UIControl sendAction:to:forEvent:] + 32
37  UIKit                             0x313bb16a -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 350
38  UIKit                             0x313bb9c8 -[UIControl touchesEnded:withEvent:] + 336
39  UIKit                             0x313b134e -[UIWindow _sendTouchesForEvent:] + 362
40  UIKit                             0x313b0cc8 -[UIWindow sendEvent:] + 256
41  UIKit                             0x3139bfc0 -[UIApplication sendEvent:] + 292
42  UIKit                             0x3139b900 _UIApplicationHandleEvent + 5084
43  GraphicsServices                  0x31eecefc PurpleEventCallback + 660
44  CoreFoundation                    0x304236f8 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 20
45  CoreFoundation                    0x304236bc __CFRunLoopDoSource1 + 160
46  CoreFoundation                    0x30415f76 __CFRunLoopRun + 514
47  CoreFoundation                    0x30415c80 CFRunLoopRunSpecific + 224
48  CoreFoundation                    0x30415b88 CFRunLoopRunInMode + 52
49  GraphicsServices                  0x31eec4a4 GSEventRunModal + 108
50  GraphicsServices                  0x31eec550 GSEventRun + 56
51  UIKit                             0x313cf322 -[UIApplication _run] + 406
52  UIKit                             0x313cce8c UIApplicationMain + 664

2011-04-09 下午3：27

Thread 0 Crashed:
0   CoreGraphics                      0x300bc854 path_create_path + 20
1   CoreGraphics                      0x300bc230 CGPathCreateByNormalizingGlyphPath + 20
2   libCGFreetype.A.dylib             0x330ca850 FT::path_builder::build_path_for_glyph(unsigned short) + 216
3   libCGFreetype.A.dylib             0x330cac20 FT::path_builder::create_path_for_glyph(unsigned short) + 60
4   libCGFreetype.A.dylib             0x330cd7c4 (anonymous namespace)::create_glyph_path(void*, CGAffineTransform const*, unsigned short) + 80
5   CoreGraphics                      0x300bc0d6 CGFontCreateGlyphPath + 22
6   CoreGraphics                      0x300bbd30 CGFontCreateGlyphBitmap8 + 244
7   CoreGraphics                      0x300bbc16 CGFontCreateGlyphBitmap + 114
8   CoreGraphics                      0x300bbaa6 create_missing_bitmaps + 218
9   CoreGraphics                      0x300bb800 CGGlyphLockLockGlyphBitmaps + 248
10  libRIP.A.dylib                    0x3175029c ripc_RenderGlyphs + 124
11  libRIP.A.dylib                    0x31752886 ripc_DrawGlyphs + 1150
12  CoreGraphics                      0x300bae3a CGContextDelegateDrawGlyphs + 26
13  CoreGraphics                      0x3018a6d4 draw_glyphs + 740
14  CoreGraphics                      0x300baa14 CGContextShowGlyphsWithAdvances + 376
15  WebCore                           0x35a803ea WebCore::showGlyphsWithAdvances(WebCore::FontPlatformData const&, CGContext*, unsigned short const*, CGSize const*, unsigned long) + 114
16  WebCore                           0x35a801c2 WebCore::Font::drawGlyphs(WebCore::GraphicsContext*, WebCore::SimpleFontData const*, WebCore::GlyphBuffer const&, int, int, WebCore::FloatPoint const&, bool) const + 810
17  WebCore                           0x35a7fe3a WebCore::Font::drawGlyphBuffer(WebCore::GraphicsContext*, WebCore::GlyphBuffer const&, WebCore::TextRun const&, WebCore::FloatPoint&) const + 114
18  WebCore                           0x35a7fb54 WebCore::Font::drawSimpleText(WebCore::GraphicsContext*, WebCore::TextRun const&, WebCore::FloatPoint const&, int, int) const + 416
19  WebCore                           0x35a7f98e WebCore::Font::drawText(WebCore::GraphicsContext*, WebCore::TextRun const&, WebCore::FloatPoint const&, int, int) const + 122
20  WebCore                           0x35a7f8e0 drawAtPoint(unsigned short const*, int, WebCore::FloatPoint const&, WebCore::Font const&, WebCore::GraphicsContext*, WebCore::BidiStatus*, int) + 136
21  WebCore                           0x35b26220 -[NSString(WebStringDrawing) __web_drawInRect:withFont:ellipsis:alignment:letterSpacing:lineSpacing:includeEmoji:truncationRect:measureOnly:renderedStringOut:] + 3600
22  WebCore                           0x35b253fe -[NSString(WebStringDrawing) __web_drawInRect:withFont:ellipsis:alignment:letterSpacing:lineSpacing:includeEmoji:truncationRect:measureOnly:] + 82
23  WebCore                           0x35b2539a -[NSString(WebStringDrawing) _web_drawInRect:withFont:ellipsis:alignment:lineSpacing:includeEmoji:truncationRect:measureOnly:] + 78
24  WebCore                           0x35b2533a -[NSString(WebStringDrawing) _web_drawInRect:withFont:ellipsis:alignment:lineSpacing:includeEmoji:truncationRect:] + 66
25  UIKit                             0x313cb61c -[NSString(UIStringDrawing) _drawInRect:withFont:lineBreakMode:alignment:lineSpacing:includeEmoji:truncationRect:] + 92
26  UIKit                             0x313cb5a6 -[NSString(UIStringDrawing) drawInRect:withFont:lineBreakMode:alignment:lineSpacing:includeEmoji:] + 62
27  UIKit                             0x313cb6c4 -[NSString(UIStringDrawing) drawInRect:withFont:lineBreakMode:alignment:lineSpacing:] + 56
28  UIKit                             0x313bd954 -[UILabel _drawTextInRect:baselineCalculationOnly:] + 2096
29  UIKit                             0x313bd10c -[UILabel drawTextInRect:] + 44
30  UIKit                             0x313bcf70 -[UILabel drawRect:] + 52
31  UIKit                             0x313ab2d2 -[UIView(CALayerDelegate) drawLayer:inContext:] + 258
32  QuartzCore                        0x32d7f2fe -[CALayer drawInContext:] + 86
33  QuartzCore                        0x32d7f07c backing_callback(CGContext*, void*) + 32
34  QuartzCore                        0x32d7eaf2 CABackingStoreUpdate + 1226
35  QuartzCore                        0x32d7e35c -[CALayer _display] + 724
36  QuartzCore                        0x32d7e06a -[CALayer display] + 134
37  QuartzCore                        0x32d7dfb0 CALayerDisplayIfNeeded + 176
38  QuartzCore                        0x32d7356e CA::Context::commit_transaction(CA::Transaction*) + 214
39  QuartzCore                        0x32d7337c CA::Transaction::commit() + 184
40  QuartzCore                        0x32d96f96 CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 46
41  CoreFoundation                    0x3041ec52 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 10
42  CoreFoundation                    0x3041eac6 __CFRunLoopDoObservers + 406
43  CoreFoundation                    0x304160c4 __CFRunLoopRun + 848
44  CoreFoundation                    0x30415c80 CFRunLoopRunSpecific + 224
45  CoreFoundation                    0x30415b88 CFRunLoopRunInMode + 52
46  GraphicsServices                  0x31eec4a4 GSEventRunModal + 108
47  GraphicsServices                  0x31eec550 GSEventRun + 56
48  UIKit                             0x313cf322 -[UIApplication _run] + 406
49  UIKit                             0x313cce8c UIApplicationMain + 664