无法在 iOS 应用程序中重新加载 TableView 数据

Question

我发现自己没有办法让这个应用程序运行起来。我的应用程序使用拆分视图来显示列表。 “主”列表应包含用户的 Facebook 好友列表。由于该应用程序不会强制您登录，因此如果您尚未登录，它会在您登录之前在列表中显示“您没有朋友”。我的问题是，一旦我加载了所有朋友并致电[self.tableView reloadData] 我的程序在那里崩溃了一些，尽管我尽了最大努力调试它，但我找不到它。方法是

    - (void)request:(FBRequest *)request didLoad:(id)result
    {
        if ([result isKindOfClass:[NSArray class]] && ([result count] > 0)) {
            result = [result objectAtIndex:0];
        }
        switch (((Facebook *)[Facebook shared]).currentCall) {
            case graphUserFriends:
            {
                _friends = [NSMutableArray array];
                NSArray *resultData = [result objectForKey:@"data"];
                if ([resultData count] > 0) 
                {
                    for (NSUInteger i=0; i<[resultData count] && i < 25; i++) 
                    {
                        NSDictionary *friendDictionary = [resultData objectAtIndex:i];
                        FbFriend * f = [[[FbFriend alloc] initWithName:[friendDictionary objectForKey:@"name"] Id:[friendDictionary objectForKey:@"id"]] autorelease];
                        [_friends addObject:f];
                    }
                }
                [self.tableView reloadData];
                break;
            }
            default:
                break;
        }
    }

整个源代码（和Xcode 4项目）可以从https://skydrive.live.com/redir.aspx?cid=04b38cdd7b38bb7f&resid=4B38CDD7B38BB7F!798&parid=4B38CDD7B38BB7F!470&authkey=!API4iVva95nZFL8

控制台（崩溃时）：

GNU gdb 6.3.50-20050815 (Apple version gdb-1708) (Mon Aug 15 16:03:10 UTC 2011)
Copyright 2004 Free Software Foundation, Inc.
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This GDB was configured as "x86_64-apple-darwin".sharedlibrary apply-load-rules all
Attaching to process 48870.
Catchpoint 3 (throw)Pending breakpoint 1 - "objc_exception_throw" resolved
Current language:  auto; currently objective-c
(gdb) bt
#0  0x0156ecf0 in objc_exception_throw ()
#1  0x013c9674 in -[__NSArrayI objectAtIndex:] ()
#2  0x00454805 in -[UITableViewDataSource tableView:heightForRowAtIndexPath:] ()
#3  0x0026427a in -[UITableViewController tableView:heightForRowAtIndexPath:] ()
#4  0x0020f548 in -[UISectionRowData refreshWithSection:tableView:tableViewRowData:] ()
#5  0x00211722 in -[UITableViewRowData numberOfRows] ()
#6  0x000c17c7 in -[UITableView noteNumberOfRowsChanged] ()
#7  0x000c12c1 in -[UITableView reloadData] ()
#8  0x0000247e in -[MasterViewController request:didLoad:] (self=0x6a491e0, _cmd=0x12e65, request=0x681e930, result=0x6824250) at /Users/CheckM8/Documents/Xcode 4/Projects/iPeople4/iPeople4/MasterViewController.m:46
#9  0x00009d36 in -[FBRequest handleResponseData:] (self=0x681e930, _cmd=0x1397a, data=0x6a76c60) at /Users/CheckM8/Documents/Xcode 4/facebook-facebook-ios-sdk-74358cd/src/FBRequest.m:261
#10 0x0000a357 in -[FBRequest connectionDidFinishLoading:] (self=0x681e930, _cmd=0xade62e, connection=0x681ec40) at /Users/CheckM8/Documents/Xcode 4/facebook-facebook-ios-sdk-74358cd/src/FBRequest.m:346
#11 0x00a29a59 in ___NSURLConnectionDidFinishLoading_block_invoke_0 ()
#12 0x00a27e94 in __65-[NSURLConnectionInternal _withConnectionAndDelegate:onlyActive:]_block_invoke_0 ()
#13 0x00a28eb7 in -[NSURLConnectionInternalConnection invokeForDelegate:] ()
#14 0x00a27e4f in -[NSURLConnectionInternal _withConnectionAndDelegate:onlyActive:] ()
#15 0x00a27fd5 in -[NSURLConnectionInternal _withActiveConnectionAndDelegate:] ()
#16 0x0096cf6a in _NSURLConnectionDidFinishLoading ()
#17 0x0398fbbd in URLConnectionClient::_clientDidFinishLoading ()
#18 0x03a5c5ea in URLConnectionClient::ClientConnectionEventQueue::processAllEventsAndConsumePayload ()
#19 0x03986298 in URLConnectionClient::processEvents ()
#20 0x03a5c16b in non-virtual thunk to URLConnectionInstanceData::multiplexerClientPerform() ()
#21 0x03986137 in MultiplexerSource::perform ()
#22 0x013b197f in __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ ()
#23 0x01314b73 in __CFRunLoopDoSources0 ()
#24 0x01314454 in __CFRunLoopRun ()
#25 0x01313db4 in CFRunLoopRunSpecific ()
#26 0x01313ccb in CFRunLoopRunInMode ()
#27 0x012c6879 in GSEventRunModal ()
#28 0x012c693e in GSEventRun ()
#29 0x00034a9b in UIApplicationMain ()
#30 0x00001d82 in main (argc=1, argv=0xbfffed64) at /Users/CheckM8/Documents/Xcode 4/Projects/iPeople4/iPeople4/main.m:16
#31 0x00001cf5 in start ()

Answer 1

你犯了一个典型的内存管理错误：你直接访问你的ivars并且它烧毁了你。

_friends = [NSMutableArray array];

这是保留不足（稍后会崩溃），如果 _friends 有先前的值，也可能发生泄漏。除了在 dealloc 和 init 中之外，您应该始终对 ivars 使用访问器：

self.friends = [NSMutableArray array];
...
[self.friends addObject:f];

---

编辑：从您的堆栈跟踪中，您的错误位于表视图数据源的 tableView:heightForRowAtIndexPath: 中。看起来您正在读取数组的末尾。