Question

My iPhone app is a Tab Bar Application, which has 5 tabs. In each tab, there is a table view, embedded with navigation controller. When these table views appear, data will be loaded from database.

When I switch the tabs very fast by tapping the tab bar randomly, the app crashes sometimes.
The error is:

+[UIWindow length]: unrecognized selector sent to class 0x3e055bd4
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[UIWindow length]: unrecognized selector sent to class 0x3e055bd4'
terminate called after throwing an instance of 'NSException'

Does anyone have advices or hints about find out the reason of the problem?

P.S. I created another similar but simpler app, which cannot be crashed by this way.

---

More info about calling stack:

> *** Call stack at first throw:
(
 0   CoreFoundation                      0x31785fd3 __exceptionPreprocess + 114
 1   libobjc.A.dylib                     0x320118a5 objc_exception_throw + 24
 2   CoreFoundation                      0x31789af3 +[NSObject(NSObject) doesNotRecognizeSelector:] + 102
 3   CoreFoundation                      0x31788f15 ___forwarding___ + 508
 4   CoreFoundation                      0x3171b680 _CF_forwarding_prep_0 + 48
 5   UIKit                               0x3019a3ff -[UITableHeaderFooterView setText:] + 30
 6   UIKit                               0x3028239d -[UITableView(UITableViewInternal) _sectionHeaderView:withFrame:forSection:opaque:reuseViewIfPossible:] + 488
 7   UIKit                               0x30199e41 -[UITableView(UITableViewInternal) _sectionHeaderViewWithFrame:forSection:opaque:reuseViewIfPossible:] + 60
 8   UIKit                               0x3016bcb1 -[UITableView(_UITableViewPrivate) _updateVisibleHeadersAndFootersNow:] + 852
 9   UIKit                               0x3016b1a1 -[UITableView(_UITableViewPrivate) _updateVisibleCellsNow:] + 1408
 10  UIKit                               0x301693c1 -[UITableView layoutSubviews] + 140
 11  UIKit                               0x301276ab -[UIView(CALayerDelegate) _layoutSublayersOfLayer:] + 26
 12  CoreFoundation                      0x317117ff -[NSObject(NSObject) performSelector:withObject:] + 22
 13  QuartzCore                          0x321e2585 -[CALayer layoutSublayers] + 120
 14  QuartzCore                          0x321e233d CALayerLayoutIfNeeded + 184
 15  QuartzCore                          0x321e1e0f _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 210
 16  QuartzCore                          0x321e1b69 _ZN2CA11Transaction6commitEv + 192
 17  QuartzCore                          0x321e740d _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 52
 18  CoreFoundation                      0x3175ba49 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 16
 19  CoreFoundation                      0x3175d475 __CFRunLoopDoObservers + 412
 20  CoreFoundation                      0x3175e77b __CFRunLoopRun + 854
 21  CoreFoundation                      0x317078eb CFRunLoopRunSpecific + 230
 22  CoreFoundation                      0x317077f3 CFRunLoopRunInMode + 58
 23  GraphicsServices                    0x33ac26ef GSEventRunModal + 114
 24  GraphicsServices                    0x33ac279b GSEventRun + 62
 25  UIKit                               0x3011e2a7 -[UIApplication _run] + 402
 26  UIKit                               0x3011ce17 UIApplicationMain + 670
 27  MyAPP                            0x00002193 main + 70
 28  MyAPP                            0x00002114 start + 52
)

Answer 1

Eventually, I found the problem.

I init a subview in viewWillApear: and use it in tableView:viewForHeaderInSection: and release the subview in viewDidDisappear:.

I changed the init/release into viewDidLoad: and viewDidUnload:. Then the problem is gone.

Thank both answerers and hope this answer will help others.