UICollectionView reloadData 遇上 layoutAttributesForSupplementaryElementOfKind “crash”
crash log:
2015-12-20 15:48:46.076 iosclient[1993:46171] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 1 beyond bounds for empty array'
*** First throw call stack:
(
0 CoreFoundation 0x01841a84 __exceptionPreprocess + 180
1 libobjc.A.dylib 0x00ec7e02 objc_exception_throw + 50
2 CoreFoundation 0x0170dd23 -[__NSArrayM objectAtIndex:] + 243
3 CoreFoundation 0x017867f8 -[NSArray objectAtIndexedSubscript:] + 40
4 UIKit 0x02774673 -[UICollectionViewFlowLayout _frameForHeaderInSection:usingData:] + 74
5 UIKit 0x0276dbc9 -[UICollectionViewFlowLayout layoutAttributesForHeaderInSection:usingData:] + 72
6 UIKit 0x0276edcc -[UICollectionViewFlowLayout layoutAttributesForSupplementaryViewOfKind:atIndexPath:] + 228
7 UIKit 0x02795f76 -[UICollectionViewData layoutAttributesForSupplementaryElementOfKind:atIndexPath:] + 477
8 UIKit 0x0273e68b -[UICollectionView layoutAttributesForSupplementaryElementOfKind:atIndexPath:] + 90
9 iosclient 0x0022bb69 _TFE9iosclientCSo16UICollectionView14scrollToHeaderfS0_FSiT_ + 153
10 iosclient 0x0022bd6f _TToFE9iosclientCSo16UICollectionView14scrollToHeaderfS0_FSiT_ + 47
11 iosclient 0x0024d678 _TFC9iosclient21RoomMapViewController13onFinishEventfS0_FSiT_ + 824
12 iosclient 0x00251615 _TTWC9iosclient21RoomMapViewControllerS_13EnentDelegateS_FS1_13onFinishEventuRq_S1__fq_FSiT_ + 53
13 iosclient 0x00199363 _TFC9iosclient12EventHandler4donefS0_FSiT_ + 355
14 iosclient 0x001991f1 _TFC9iosclient12EventHandler4donefS0_FT_T_ + 33
15 iosclient 0x0025265b _TFFC9iosclient21RoomMapViewController26dogetRoomMapLeafByBranchIdFS0_FSdT_U_FTGSqCSo7NSError_GSqPSs9AnyObject___T_ + 779
16 iosclient 0x002500cd _TPA__TFFC9iosclient21RoomMapViewController26dogetRoomMapLeafByBranchIdFS0_FSdT_U_FTGSqCSo7NSError_GSqPSs9AnyObject___T_ + 77
17 iosclient 0x0022785f _TFFC9iosclient9WebClient16doGetRoomMapLeafFS0_FTSd14LastRefushTimeSd8callbackFTGSqCSo7NSError_GSqPSs9AnyObject___T__T_U_FTGSqS1__GSqPS2____T_ + 95
18 iosclient 0x00222c57 _TPA__TFFC9iosclient9WebClient16doGetRoomMapLeafFS0_FTSd14LastRefushTimeSd8callbackFTGSqCSo7NSError_GSqPSs9AnyObject___T__T_U_FTGSqS1__GSqPS2____T_ + 87
19 iosclient 0x0026b639 _TFFC9iosclient4Http8get_gzipFS0_FTSS5paramGSqGVSs10DictionarySSPSs9AnyObject___8callbackFTGSqCSo7NSError_GSqPS2____T__T_U_FTGSqCSo13NSURLResponse_GSqCSo6NSData_GSqS3___T_ + 905
20 iosclient 0x0026a24d _TPA__TFFC9iosclient4Http8get_gzipFS0_FTSS5paramGSqGVSs10DictionarySSPSs9AnyObject___8callbackFTGSqCSo7NSError_GSqPS2____T__T_U_FTGSqCSo13NSURLResponse_GSqCSo6NSData_GSqS3___T_ + 125
21 iosclient 0x0026b2a2 _TTRXFo_oGSqCSo13NSURLResponse_oGSqCSo6NSData_oGSqCSo7NSError__dT__XFdCb_dGSqS__dGSqS0__dGSqS1___dT__ + 114
22 CFNetwork 0x03e8db62 __67+[NSURLConnection sendAsynchronousRequest:queue:completionHandler:]_block_invoke_2 + 177
23 Foundation 0x00b74a6b __NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
24 Foundation 0x00a988ff -[NSBlockOperation main] + 108
25 Foundation 0x00a78d84 -[__NSOperationInternal _start:] + 697
26 Foundation 0x00a78ac4 -[NSOperation start] + 83
27 Foundation 0x00a78902 __NSOQSchedule_f + 245
28 libdispatch.dylib 0x0460b9cd _dispatch_client_callout + 14
29 libdispatch.dylib 0x045f0f90 _dispatch_main_queue_callback_4CF + 910
30 CoreFoundation 0x017935fe __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 14
31 CoreFoundation 0x017512f4 __CFRunLoopRun + 2356
32 CoreFoundation 0x01750706 CFRunLoopRunSpecific + 470
33 CoreFoundation 0x0175051b CFRunLoopRunInMode + 123
34 GraphicsServices 0x050f6664 GSEventRunModal + 192
35 GraphicsServices 0x050f64a1 GSEventRun + 104
36 UIKit 0x01dd81eb UIApplicationMain + 160
37 iosclient 0x0019db4c main + 140
38 libdyld.dylib 0x04635a21 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)
遇到这种问题总是很困扰，两个都在主线程了，还会crash？！！ 这个是多线程并发？？！！
我的代码是这样的：
RoomStatusTable.reloadData()
RoomStatusTable.scrollToHeader(self.scrollToHeaderRow!)extension UICollectionView{
func scrollToHeader(section:Int){
let index = NSIndexPath(forRow: 0, inSection: section)
if let attr = layoutAttributesForSupplementaryElementOfKind(UICollectionElementKindSectionHeader, atIndexPath: index){
let top = CGPointMake(0, attr.frame.origin.y - contentInset.top)
setContentOffset(top, animated: true)
}
}
}解决方法是：
RoomStatusTable.reloadData()
NSOperationQueue.mainQueue().addOperationWithBlock({() -> Void in
if(self.scrollToHeaderRow != nil){
self.RoomStatusTable.scrollToHeader(self.scrollToHeaderRow!)
}
})加入延时执行，延时到下一个应用程序的下一个主循环