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这是代码。我尝试创建一个包含名称、大小和图像（从资源中获取）的对象，然后将该对象添加到NSMutableArray其中以在 NSTableView 中显示这些对象。但是，在我运行代码之后，我确实得到了正确的对象计数NSMutableArray和每个对象（名称、大小、图像）中的正确信息，但它仍然给我错误。你们能帮帮我吗。我是一名新的 Mac 开发人员。谢谢 ！！

这是代码：

    @implementation AppDelegate{
        NSMutableArray* _tableContents;
    }

   -(void)awakeFromNib{

        NSString* imagePath = @"USB.png";
        NSString* mountPath = @"/Volumes";

       _tableContents = [[NSMutableArray alloc]init];

      for(mountPath in [[NSWorkspace sharedWorkspace]mountedLocalVolumePaths])
      {
        if(0==[mountPath rangeOfString:@"/Volumes/"].location)
        {            

           NSString* USBpath = [[[NSWorkspace sharedWorkspace]mountedLocalVolumePaths]objectAtIndex:count];

           //get the name of USB drive
           NSString* nameOfUSB = [USBpath substringFromIndex:9];

          //get the size of USB drive
          NSNumber *volumeSize;
          NSURL *mountPathPicked = [NSURL fileURLWithPath:mountPath];

          if([mountPathPicked getResourceValue:&volumeSize forKey:NSURLVolumeTotalCapacityKey error:nil])
          {
            NSDictionary *obj = @{@"name":nameOfUSB,
                                  @"image":[NSImage imageNamed:imagePath],
                                  @"size":volumeSize
                                  };

            //after I call the following line, it will give me error !!
            [_tableContents addObject:obj];
          }
       }
        count ++;
      }
    }

//I also use the following two methods in order to show the name, and image in NSTableView
-(NSInteger)numberOfRowsInTableView:(NSTableView *)tableView{
    return [_tableCountents count];
}

-(NSView *)tableView:(NSTableView *)tableView viewForTableColumn:(NSTableColumn *)tableColumn row:(NSInteger)row{

  NSDictionary *flag = _tableContents[row];
  NSString *identifier = [tableColumn identifier];//call different col we need identifier
  if([identifier isEqualToString:@"MainCell"])
  {
      NSTableCellView *cellView = [tableView makeViewWithIdentifier:@"MainCell" owner:self];//give back specific cell named mainCell
      [cellView.textField setStringValue:flag[@"name"]];
      [cellView.imageView setImage:flag[@"image"]];
      return cellView;
  }
  return nil;
}

GUI 中没有连接问题。这是错误消息：

2013-04-25 01:16:41.321 NAMEOFPROJECT[8243:303] An uncaught exception was raised
2013-04-25 01:16:41.322 NAMEOFPROJECT[8243:303] *** -[__NSArrayI objectAtIndex:]: index 7 beyond bounds [0 .. 3]
2013-04-25 01:16:41.329 NAMEOFPROJECT[8243:303] (
0   CoreFoundation                      0x00007fff9147cb06 __exceptionPreprocess + 198
1   libobjc.A.dylib                     0x00007fff900c03f0 objc_exception_throw + 43
2   CoreFoundation                      0x00007fff9142fb53 -[__NSArrayI objectAtIndex:] + 163
3   CDTOANYDRIVE                        0x00000001000011d6 -[AppDelegate DetectingUSBDrives] + 710
4   CDTOANYDRIVE                        0x0000000100000efb -[AppDelegate awakeFromNib] + 43
5   AppKit                              0x00007fff899631a8 -[NSIBObjectData nibInstantiateWithOwner:topLevelObjects:] + 1234
6   AppKit                              0x00007fff89b79976 -[NSNib _instantiateNibWithExternalNameTable:] + 610
7   AppKit                              0x00007fff89b7a41a -[NSNib instantiateNibWithExternalNameTable:] + 17
8   AppKit                              0x00007fff89b262b4 -[NSTableRowData _unarchiveViewWithIdentifier:owner:] + 520
9   CDTOANYDRIVE                        0x000000010000174b -[AppDelegate tableView:viewForTableColumn:row:] + 219
10  AppKit                              0x00007fff89b279a2 -[NSTableRowData _addViewToRowView:atColumn:row:] + 324
11  AppKit                              0x00007fff89b2766f -[NSTableRowData _addViewsToRowView:atRow:] + 151
12  AppKit                              0x00007fff89b25c05 -[NSTableRowData _addRowViewForVisibleRow:withPriorView:] + 415
13  AppKit                              0x00007fff89b2598a -[NSTableRowData _addRowViewForVisibleRow:withPriorRowIndex:inDictionary:withRowAnimation:] + 272
14  AppKit                              0x00007fff89b24c59 -[NSTableRowData _unsafeUpdateVisibleRowEntries] + 740
15  AppKit                              0x00007fff89b247f1 -[NSTableRowData updateVisibleRowViews] + 119
16  AppKit                              0x00007fff89afc5d7 -[NSTableView layout] + 165
17  AppKit                              0x00007fff89aafe95 -[NSView _layoutSubtreeHeedingRecursionGuard:] + 112
18  CoreFoundation                      0x00007fff914754a6 __NSArrayEnumerate + 582
19  AppKit                              0x00007fff89aafff6 -[NSView _layoutSubtreeHeedingRecursionGuard:] + 465
20  CoreFoundation                      0x00007fff914754a6 __NSArrayEnumerate + 582
21  AppKit                              0x00007fff89aafff6 -[NSView _layoutSubtreeHeedingRecursionGuard:] + 465
22  CoreFoundation                      0x00007fff914754a6 __NSArrayEnumerate + 582
23  AppKit                              0x00007fff89aafff6 -[NSView _layoutSubtreeHeedingRecursionGuard:] + 465
24  CoreFoundation                      0x00007fff914754a6 __NSArrayEnumerate + 582
25  AppKit                              0x00007fff89aafff6 -[NSView _layoutSubtreeHeedingRecursionGuard:] + 465
26  AppKit                              0x00007fff89aafd2e -[NSView layoutSubtreeIfNeeded] + 615
27  AppKit                              0x00007fff89aab4dc -[NSWindow(NSConstraintBasedLayout) layoutIfNeeded] + 201
28  AppKit                              0x00007fff899d96a8 -[NSView _layoutAtWindowLevelIfNeeded] + 99
29  AppKit                              0x00007fff899d8fe6 -[NSView _sendViewWillDrawInRect:clipRootView:] + 87
30  AppKit                              0x00007fff899a59b1 -[NSView displayIfNeeded] + 1044
31  AppKit                              0x00007fff89a62a48 -[NSWindow _reallyDoOrderWindow:relativeTo:findKey:forCounter:force:isModal:] + 1377
32  AppKit                              0x00007fff89a62068 -[NSWindow _doOrderWindow:relativeTo:findKey:forCounter:force:isModal:] + 940
33  AppKit                              0x00007fff89a61c4f -[NSWindow orderWindow:relativeTo:] + 159
34  AppKit                              0x00007fff89963266 -[NSIBObjectData nibInstantiateWithOwner:topLevelObjects:] + 1424
35  AppKit                              0x00007fff8994214d loadNib + 317
36  AppKit                              0x00007fff89941679 +[NSBundle(NSNibLoading) _loadNibFile:nameTable:withZone:ownerBundle:] + 219
37  AppKit                              0x00007fff899414ae -[NSBundle(NSNibLoading) loadNibNamed:owner:topLevelObjects:] + 200
38  AppKit                              0x00007fff8994128e +[NSBundle(NSNibLoading) loadNibNamed:owner:] + 360
39  AppKit                              0x00007fff8993da2f NSApplicationMain + 398
40  CDTOANYDRIVE                        0x0000000100000e82 main + 34
41  libdyld.dylib                       0x00007fff9385a7e1 start + 0
42  ???                                 0x0000000000000003 0x0 + 3
)

上面的错误显示两次！

4

1 回答 1

1

我已经在一个迷你应用程序中尝试过你的代码，它工作正常。我可能会强调几件事：

  1. 您的异常发生在 DetectingUSBDrives 方法中，我们没有任何代码。我假设您已将代码粘贴到 awakeFromNib 方法中。
  2. 您正在count用作索引。这个变量是否初始化为零？
  3. 错误出现两次的事实表明您的单元格视图包含对您的应用程序委托的引用，这意味着每次视图创建都会调用一次 awakeFromNib。由于您在那里初始化 _tableOfContents，这可能会产生很多问题。您可能希望将所有代码移到init方法中。
于 2013-04-25T15:50:36.190 回答