Out of bounds error on addObject to NSMutableDictionary - cocoa

Question

So I am building an app in cocoa and having a bit of trouble. I want to feed text file names in many different folders to a tableview using an array controller, but it keeps throwing out of bounds errors. Heres a chunk of the code giving me trouble.
[self clear:nil]; // method that clears the NSTableView
NSString *chooserSelection = chooserItems.titleOfSelectedItem; // gets the selected folder from an NSPopUpButton
if (chooserSelection == #"All") {
path = #"/Library/Application Support/File Folder/Files/";
NSArray *folders = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:path error:nil];
NSLog(#"\nfolders = %#", folders);
for (int i = 0; i < [folders count]; i++) {
path = #"/Library/Application Support/File Folder/Files/";
NSMutableString *folderNames = [[NSMutableString stringWithString:path] init];
[folderNames insertString:folders[i] atIndex:folderNames.length];
[folderNames insertString:#"/" atIndex:folderNames.length];
NSArray *text = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:folderNames error:nil];
[myArrayController addObject: [NSMutableDictionary dictionaryWithObjectsAndKeys:text[i], #"File Name", nil]];
//This line gives the error
}
}
If I change [folders count] to 1 it shows up in the NSTableView. However on anything past that (additional passes through the for loop) i get an out of bounds error.
2013-02-26 13:17:49.679 AppName[3489:403] *** -[__NSArrayI objectAtIndex:]: index 1 beyond bounds [0 .. 0]
2013-02-26 13:17:49.683 AppName[3489:403] (
0 CoreFoundation 0x00007fff829b5f56 __exceptionPreprocess + 198
1 libobjc.A.dylib 0x00007fff84fe6d5e objc_exception_throw + 43
2 CoreFoundation 0x00007fff8295f370 -[__NSArrayI objectAtIndex:] + 208
3 AppName 0x000000010000159a -[AppDelegate tableView:objectValueForTableColumn:row:] + 106
4 AppKit 0x00007fff840a16e7 -[NSTableView _dataSourceValueForColumn:row:] + 73
5 AppKit 0x00007fff840a1167 -[NSTableView preparedCellAtColumn:row:] + 437
6 AppKit 0x00007fff840b2171 -[NSTableView _drawContentsAtRow:column:withCellFrame:] + 42
7 AppKit 0x00007fff840b05d8 -[NSTableView drawRow:clipRect:] + 1647
8 AppKit 0x00007fff840afdb5 -[NSTableView drawRowIndexes:clipRect:] + 565
9 AppKit 0x00007fff840aded7 -[NSTableView drawRect:] + 1390
10 AppKit 0x00007fff84197382 -[NSView(NSInternal) _recursive:displayRectIgnoringOpacity:inContext:topView:] + 1435
11 AppKit 0x00007fff841b564f __-[NSView(NSLayerKitGlue) drawLayer:inContext:]_block_invoke_1 + 94
12 AppKit 0x00007fff841b52fb -[NSView(NSLayerKitGlue) _drawViewBackingLayer:inContext:drawingHandler:] + 2001
13 QuartzCore 0x00007fff82c4a0dc -[CALayer drawInContext:] + 145
14 QuartzCore 0x00007fff82c49225 CABackingStoreUpdate_ + 3221
15 QuartzCore 0x00007fff82c4813a _ZN2CA5Layer8display_Ev + 1086
16 AppKit 0x00007fff841504e6 -[NSView(NSInternal) _recursiveDisplayViewsIntoLayersIfNeeded] + 163
17 AppKit 0x00007fff841505fc -[NSView(NSInternal) _recursiveDisplayViewsIntoLayersIfNeeded] + 441
18 AppKit 0x00007fff841505fc -[NSView(NSInternal) _recursiveDisplayViewsIntoLayersIfNeeded] + 441
19 AppKit 0x00007fff841505fc -[NSView(NSInternal) _recursiveDisplayViewsIntoLayersIfNeeded] + 441
20 AppKit 0x00007fff84150168 -[NSView(NSLayerKitGlue) _drawRectAsLayerTree:] + 128
21 AppKit 0x00007fff8401653e -[NSView _drawRect:clip:] + 4382
22 AppKit 0x00007fff8401406d -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 3020
23 AppKit 0x00007fff84014b5e -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 5821
24 AppKit 0x00007fff84012da3 -[NSThemeFrame _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 270
25 AppKit 0x00007fff8400e1bb -[NSView _displayRectIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:] + 4755
26 AppKit 0x00007fff84006c35 -[NSView displayIfNeeded] + 1676
27 AppKit 0x00007fff84006375 _handleWindowNeedsDisplayOrLayoutOrUpdateConstraints + 648
28 CoreFoundation 0x00007fff829758e7 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
29 CoreFoundation 0x00007fff82975846 __CFRunLoopDoObservers + 374
30 CoreFoundation 0x00007fff8294aaf9 __CFRunLoopRun + 825
31 CoreFoundation 0x00007fff8294a486 CFRunLoopRunSpecific + 230
32 AppKit 0x00007fff84459b08 -[NSMenu _internalPerformActionForItemAtIndex:] + 38
33 AppKit 0x00007fff842e86f9 -[NSCarbonMenuImpl _carbonCommandProcessEvent:handlerCallRef:] + 138
34 AppKit 0x00007fff841349bb NSSLMMenuEventHandler + 339
35 HIToolbox 0x00007fff89d08234 _ZL23DispatchEventToHandlersP14EventTargetRecP14OpaqueEventRefP14HandlerCallRec + 1263
36 HIToolbox 0x00007fff89d07840 _ZL30SendEventToEventTargetInternalP14OpaqueEventRefP20OpaqueEventTargetRefP14HandlerCallRec + 446
37 HIToolbox 0x00007fff89d1e6db SendEventToEventTarget + 76
38 HIToolbox 0x00007fff89d647b5 _ZL18SendHICommandEventjPK9HICommandjjhPKvP20OpaqueEventTargetRefS5_PP14OpaqueEventRef + 398
39 HIToolbox 0x00007fff89e4be2d SendMenuCommandWithContextAndModifiers + 56
40 HIToolbox 0x00007fff89e935b5 SendMenuItemSelectedEvent + 253
41 HIToolbox 0x00007fff89d5d883 _ZL19FinishMenuSelectionP13SelectionDataP10MenuResultS2_ + 101
42 HIToolbox 0x00007fff89e8bfed _ZL19PopUpMenuSelectCoreP8MenuData5PointdS1_tjPK4RecttjS4_S4_PK10__CFStringPP13OpaqueMenuRefPt + 1660
43 HIToolbox 0x00007fff89e8c2ac _HandlePopUpMenuSelection7 + 621
44 AppKit 0x00007fff842eb3c5 _NSSLMPopUpCarbonMenu3 + 3860
45 AppKit 0x00007fff846990fa _NSPopUpCarbonMenu3 + 39
46 AppKit 0x00007fff842e952a -[NSCarbonMenuImpl popUpMenu:atLocation:width:forView:withSelectedItem:withFont:withFlags:withOptions:] + 322
47 AppKit 0x00007fff844ca1f1 -[NSPopUpButtonCell trackMouse:inRect:ofView:untilMouseUp:] + 564
48 AppKit 0x00007fff840cb7f6 -[NSControl mouseDown:] + 786
49 AppKit 0x00007fff84096c98 -[NSWindow sendEvent:] + 6306
50 AppKit 0x00007fff840303a5 -[NSApplication sendEvent:] + 5593
51 AppKit 0x00007fff83fc6a0e -[NSApplication run] + 555
52 AppKit 0x00007fff84242eac NSApplicationMain + 867
53 AppName 0x0000000100001152 main + 34
54 AppName 0x0000000100001124 start + 52
)
I can also more the addObject line to the line below the for loop which will display the filename of the last file. But I cannot figure out where the out of bounds error is coming from.

Answer 1

You are using the index i first for the count of folders in path, and then for the count of files in that respective folder. So you are depending on there being at least as many files in folder N as the number of N.
For example if you have three folders
folder0
folder1
folder2
then when you iterate over folder2 (i=2), there had better be at least 3 items in the folder as you are accessing item 3 (text[2]). When there are fewer items, you will get that out-of-bounds error.
You probably mean to do something like this:
NSMutableDictionary* dict =
[NSMutableDictionary dictionaryWithObjectsAndKeys:text, folders[i], nil];
That will get you an array of dictionaries. Each dictionary has a single key (the name of the folder,) and a single value (an array of filenames).
You could simplify your data structure further by flattening this to a single dictionary (not inside an array). Each key is a folder name, each value is the array of filenames.