重新加载NSOutlineView经常导致崩溃

Question

在我的应用程序中，我想搜索mac中的文件，并且如果我得到了需要使用该文件重新加载NSOutlineView的文件。如果我经常重新加载NSOutlineView中的物品，会导致崩溃。

//像这样我打电话搜索文件的方法。

[self performSelectorInBackground:@selector(searchFiles) withObject:self]; 

//重新加载outlineview

- (void)searchFiles { 
    ------------------------- 
    ------------------------- 
    NSMutableDictionary *dictionary = [NSMutableDictionary dictionaryWithObject:filelistArray forKey:@"children"]; 
    [dictionary setObject:[NSString stringWithFormat:@"%ld",[filelist count]] forKey:@"parent"]; 
    [listArray addObject:dictionary]; 
    [outLineView reloadData]; 
} 

//代表的OutlineView

- (BOOL)outlineView:(NSOutlineView *)outlineView isItemExpandable:(id)item { 

    if ([item isKindOfClass:[NSDictionary class]]) 
     return YES; 
    else 
     return NO; 
} 

- (NSInteger)outlineView:(NSOutlineView *)outlineView numberOfChildrenOfItem:(id)item { 

    if (item == nil) 
     return [listArray count]; 

    if ([item isKindOfClass:[NSDictionary class]]) 
     return [[item objectForKey:@"children"] count]; 

    return 0; 
} 


- (id)outlineView:(NSOutlineView *)outlineView child:(NSInteger)index ofItem:(id)item { 

    if (item == nil) 
     return [listArray objectAtIndex:index]; 

    return [[item objectForKey:@"children"] objectAtIndex:index]; 

    return nil; 
} 


- (id)outlineView:(NSOutlineView *)outlineView objectValueForTableColumn:(NSTableColumn *)theColumn byItem:(id)item { 

    if ([item isKindOfClass:[NSDictionary class]]) 
     return [item objectForKey:@"parent"]; 
    else 
     return item; 
    return nil; 
} 

//崩溃日志

2013-02-18 15:44:13.800 OutLineViewReloadDemo[3054:303] *** Assertion failure in -[NSOutlineView _expandItemEntry:expandChildren:startLevel:], /SourceCache/AppKit/AppKit-1187.34/TableView.subproj/NSOutlineView.m:1309 
2013-02-18 15:44:13.802 OutLineViewReloadDemo[3054:303] (null) should not be expanded already! 
2013-02-18 15:44:13.806 OutLineViewReloadDemo[3054:303] (
    0 CoreFoundation      0x00007fff81eef0a6 __exceptionPreprocess + 198 
    1 libobjc.A.dylib      0x00007fff878a53f0 objc_exception_throw + 43 
    2 CoreFoundation      0x00007fff81eeeee8 +[NSException raise:format:arguments:] + 104 
    3 Foundation       0x00007fff8d4876a2 -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 189 
    4 AppKit        0x00007fff83fcb9b0 -[NSOutlineView _expandItemEntry:expandChildren:startLevel:] + 1153 
    5 AppKit        0x00007fff83fb1c42 -[NSOutlineView _uncachedNumberOfRows] + 379 
    6 AppKit        0x00007fff83feb938 -[NSOutlineView frameOfCellAtColumn:row:] + 66 
    7 AppKit        0x00007fff83feb44f -[NSTableView drawRow:clipRect:] + 1636 
    8 AppKit        0x00007fff83fdb4c3 -[NSTableView drawRowIndexes:clipRect:] + 397 
    9 AppKit        0x00007fff83fdb321 -[NSOutlineView drawRowIndexes:clipRect:] + 113 
    10 AppKit        0x00007fff83fd9ea6 -[NSTableView drawRect:] + 1269 
    11 AppKit        0x00007fff83ebe144 -[NSView _drawRect:clip:] + 4217 
    12 AppKit        0x00007fff83ebc7a1 -[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] + 1656 
    13 AppKit        0x00007fff83ebcbb9 -[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] + 2704 
    14 AppKit        0x00007fff83ebcbb9 -[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] + 2704 
    15 AppKit        0x00007fff83eba7d2 -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 817 
    16 AppKit        0x00007fff83ebbb24 -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 5763 
    17 AppKit        0x00007fff83ebbb24 -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 5763 
    18 AppKit        0x00007fff83eba223 -[NSThemeFrame _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 314 
    19 AppKit        0x00007fff83eb5e4d -[NSView _displayRectIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:] + 4675 
    20 AppKit        0x00007fff83e7fd73 -[NSView displayIfNeeded] + 1830 
    21 AppKit        0x00007fff83e7f2ac _handleWindowNeedsDisplayOrLayoutOrUpdateConstraints + 738 
    22 Foundation       0x00007fff8d4ee513 __NSFireTimer + 96 
    23 CoreFoundation      0x00007fff81eabda4 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 20 
    24 CoreFoundation      0x00007fff81eab8bd __CFRunLoopDoTimer + 557 
    25 CoreFoundation      0x00007fff81e91099 __CFRunLoopRun + 1513 
    26 CoreFoundation      0x00007fff81e906b2 CFRunLoopRunSpecific + 290 
    27 HIToolbox       0x00007fff8b28b0a4 RunCurrentEventLoopInMode + 209 
    28 HIToolbox       0x00007fff8b28ae42 ReceiveNextEventCommon + 356 
    29 HIToolbox       0x00007fff8b28acd3 BlockUntilNextEventMatchingListInMode + 62 
    30 AppKit        0x00007fff83e7c613 _DPSNextEvent + 685 
    31 AppKit        0x00007fff83e7bed2 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 128 
    32 AppKit        0x00007fff83e73283 -[NSApplication run] + 517 
    33 AppKit        0x00007fff83e17cb6 NSApplicationMain + 869 
    34 OutLineViewReloadDemo    0x0000000100001772 main + 34 
    35 libdyld.dylib      0x00007fff8206a7e1 start + 0 
    36 ???         0x0000000000000003 0x0 + 3 
) 

我的问题是如何避免这次崩溃？

编辑1：

添加[outline reloadData];in dispatch_async(dispatch_get_main_queue(),后其工作完全没有任何崩溃。但是如果我扩展一些项目会导致崩溃。我无法弄清楚问题所在。这是我的崩溃日志。

*** Collection <__NSArrayM: 0x106536f70> was mutated while being enumerated. 
0 CoreFoundation      0x00007fff81eef0a6 __exceptionPreprocess + 198 
    1 libobjc.A.dylib      0x00007fff878a53f0 objc_exception_throw + 43 
    2 CoreFoundation      0x00007fff81f82f98 __NSFastEnumerationMutationHandler + 232 
    3 CoreFoundation      0x00007fff81ec7281 -[NSArray containsObject:] + 177 
    4 OutlineViewDemo      0x000000010005ad60 -[MC_DuplicateFinderViewController outlineView:willDisplayCell:forTableColumn:item:] + 800 
    5 AppKit        0x00007fff83fed519 -[NSTableView preparedCellAtColumn:row:] + 1573 
    6 AppKit        0x00007fff83feccfc -[NSOutlineView preparedCellAtColumn:row:] + 56 
    7 AppKit        0x00007fff83fecc07 -[NSTableView _drawContentsAtRow:column:withCellFrame:] + 47 
    8 AppKit        0x00007fff83fecb7b -[NSOutlineView _drawContentsAtRow:column:withCellFrame:] + 94 
    9 AppKit        0x00007fff83feb63e -[NSTableView drawRow:clipRect:] + 2131 
    10 AppKit        0x00007fff83fdb4c3 -[NSTableView drawRowIndexes:clipRect:] + 397 
    11 AppKit        0x00007fff83fdb321 -[NSOutlineView drawRowIndexes:clipRect:] + 113 
    12 AppKit        0x00007fff83fd9ea6 -[NSTableView drawRect:] + 1269 
    13 AppKit        0x00007fff83ebe144 -[NSView _drawRect:clip:] + 4217 
    14 AppKit        0x00007fff83ebc7a1 -[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] + 1656 
    15 AppKit        0x00007fff83ebcbb9 -[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] + 2704 
    16 AppKit        0x00007fff83eba7d2 -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 817 
    17 AppKit        0x00007fff83ebbb24 -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 5763 
    18 AppKit        0x00007fff83ebbb24 -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 5763 
    19 AppKit        0x00007fff83ebbb24 -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 5763 
    20 AppKit        0x00007fff83ebbb24 -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 5763 
    21 AppKit        0x00007fff83ebbb24 -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 5763 
    22 AppKit        0x00007fff83ebbb24 -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 5763 
    23 AppKit        0x00007fff83ebbb24 -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 5763 
    24 AppKit        0x00007fff83ebbb24 -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 5763 
    25 AppKit        0x00007fff83ebbb24 -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 5763 
    26 AppKit        0x00007fff83ebbb24 -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 5763 
    27 AppKit        0x00007fff83eba223 -[NSThemeFrame _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 314 
    28 AppKit        0x00007fff83eb5e4d -[NSView _displayRectIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:] + 4675 
    29 AppKit        0x00007fff83e7fd73 -[NSView displayIfNeeded] + 1830 
    30 AppKit        0x00007fff83e7f2ac _handleWindowNeedsDisplayOrLayoutOrUpdateConstraints + 738 
    31 AppKit        0x00007fff8444a971 __83-[NSWindow _postWindowNeedsDisplayOrLayoutOrUpdateConstraintsUnlessPostingDisabled]_block_invoke_01208 + 46 
    32 CoreFoundation      0x00007fff81eb59b7 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23 
    33 CoreFoundation      0x00007fff81eb5921 __CFRunLoopDoObservers + 369 
    34 CoreFoundation      0x00007fff81e90d88 __CFRunLoopRun + 728 
    35 CoreFoundation      0x00007fff81e906b2 CFRunLoopRunSpecific + 290 
    36 HIToolbox       0x00007fff8b28b0a4 RunCurrentEventLoopInMode + 209 
    37 HIToolbox       0x00007fff8b28ae42 ReceiveNextEventCommon + 356 
    38 HIToolbox       0x00007fff8b28acd3 BlockUntilNextEventMatchingListInMode + 62 
    39 AppKit        0x00007fff83e7c613 _DPSNextEvent + 685 
    40 AppKit        0x00007fff83e7bed2 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 128 
    41 AppKit        0x00007fff83e73283 -[NSApplication run] + 517 
    42 AppKit        0x00007fff83e17cb6 NSApplicationMain + 869 
    43 OutlineViewDemo      0x0000000100001462 main + 34 
    44 libdyld.dylib      0x00007fff8206a7e1 start + 0 
) 

Answer 1

performSelectorInBackground:withObject:运行在一个新的后台线程的选择，而在UI更新（和大多数其他操作）必须在主线程上执行。因此，崩溃，将是我的猜测。

一个简单的方式来获得控制从主线程更新是使用大中央调度（GCD），像这样：

dispatch_async(dispatch_get_main_queue(), ^{ 
    [outLineView reloadData]; 
});