我有一个简单的文档应用程序，基于文档模板，在Mac OS X 10.7上选择“还原为已保存 - >上次打开的版本”菜单项时抛出异常。
异常不在我的代码中，它在Cocoa中。它似乎也与我正在做的任何事情无关。我的应用程序非常简单（在这个阶段），几乎是一个基于vanilla cocoa文档的应用程序，基于最新稳定版Xcode中包含的模板。
我意识到这可能是Lion中的一个错误，但我需要找到一种解决方法。
请参阅下面的异常，以及我的NSDocument子类的全部内容（非常小）。
重现的步骤
异常
2011-09-04 07:10:29.182 myapp[15433:707] *** -[NSPathStore2 stringByAppendingPathExtension:]: nil argument
2011-09-04 07:10:29.191 myapp[15433:707] (
0 CoreFoundation 0x00007fff89c2b986 __exceptionPreprocess + 198
1 libobjc.A.dylib 0x00007fff90c6ed5e objc_exception_throw + 43
2 CoreFoundation 0x00007fff89c2b7ba +[NSException raise:format:arguments:] + 106
3 CoreFoundation 0x00007fff89c2b744 +[NSException raise:format:] + 116
4 Foundation 0x00007fff86d2b172 -[NSPathStore2 stringByAppendingPathExtension:] + 112
5 AppKit 0x00007fff9148f8c3 -[NSDocument _preserveCurrentVersionForReason:error:] + 579
6 AppKit 0x00007fff9147655b __-[NSDocument _revertToVersion:preservingFirst:error:]_block_invoke_3 + 99
7 Foundation 0x00007fff86ef28c3 __-[NSFileCoordinator coordinateReadingItemAtURL:options:error:byAccessor:]_block_invoke_1 + 113
8 Foundation 0x00007fff86ef2f34 -[NSFileCoordinator(NSPrivate) _invokeAccessor:orDont:thenRelinquishAccessClaimForID:] + 202
9 Foundation 0x00007fff86d98a28 -[NSFileCoordinator(NSPrivate) _coordinateReadingItemAtURL:options:error:byAccessor:] + 663
10 Foundation 0x00007fff86ef284c -[NSFileCoordinator coordinateReadingItemAtURL:options:error:byAccessor:] + 79
11 AppKit 0x00007fff91484b41 __-[NSDocument _revertToVersion:preservingFirst:error:]_block_invoke_1 + 347
12 AppKit 0x00007fff914901e3 -[NSDocument performSynchronousFileAccessUsingBlock:] + 42
13 AppKit 0x00007fff9148fc90 -[NSDocument _revertToVersion:preservingFirst:error:] + 125
14 AppKit 0x00007fff91476cf9 -[NSDocument _revertToDiscardRecentChangesPreservingFirst:error:] + 43
15 AppKit 0x00007fff91477094 __-[NSDocument _revertToDiscardRecentChangesThenContinue:]_block_invoke_3 + 164
16 AppKit 0x00007fff91474851 __-[NSDocument performSynchronousFileAccessUsingBlock:]_block_invoke_1 + 19
17 AppKit 0x00007fff91475bda -[NSDocument continueFileAccessUsingBlock:] + 227
18 AppKit 0x00007fff91490413 -[NSDocument _performFileAccessOnMainThread:usingBlock:] + 466
19 AppKit 0x00007fff9149023f -[NSDocument performSynchronousFileAccessUsingBlock:] + 134
20 AppKit 0x00007fff91495891 __-[NSDocument _revertToDiscardRecentChangesThenContinue:]_block_invoke_2 + 301
21 AppKit 0x00007fff914909a9 -[NSDocument _something:wasPresentedWithResult:soContinue:] + 21
22 AppKit 0x00007fff91381bee -[NSAlert didEndAlert:returnCode:contextInfo:] + 93
23 AppKit 0x00007fff9138e356 -[NSApplication endSheet:returnCode:] + 275
24 AppKit 0x00007fff91381ab4 -[NSAlert buttonPressed:] + 265
25 CoreFoundation 0x00007fff89c1b11d -[NSObject performSelector:withObject:] + 61
26 AppKit 0x00007fff911dd852 -[NSApplication sendAction:to:from:] + 139
27 AppKit 0x00007fff911dd784 -[NSControl sendAction:to:] + 88
28 AppKit 0x00007fff911dd6af -[NSCell _sendActionFrom:] + 137
29 AppKit 0x00007fff911dcb7a -[NSCell trackMouse:inRect:ofView:untilMouseUp:] + 2014
30 AppKit 0x00007fff9125c57c -[NSButtonCell trackMouse:inRect:ofView:untilMouseUp:] + 489
31 AppKit 0x00007fff911db786 -[NSControl mouseDown:] + 786
32 AppKit 0x00007fff911a666e -[NSWindow sendEvent:] + 6280
33 AppKit 0x00007fff9113ef19 -[NSApplication sendEvent:] + 5665
34 AppKit 0x00007fff910d542b -[NSApplication run] + 548
35 AppKit 0x00007fff9135352a NSApplicationMain + 867
36 myapp 0x00000001000018d2 main + 34
37 myapp 0x00000001000018a4 start + 52
)
NSDocument Subclass
@implementation MyTextDocument
@synthesize textStorage;
@synthesize textView;
+ (BOOL)autosavesInPlace
{
return YES;
}
- (id)init
{
self = [super init];
if (self) {
self.textStorage = nil;
self.textView = nil;
textContentToLoad = [@"" retain];
}
return self;
}
- (NSString *)windowNibName
{
return @"MyTextDocument";
}
- (void)windowControllerDidLoadNib:(NSWindowController *)aController
{
[super windowControllerDidLoadNib:aController];
self.textStorage = self.textView.textStorage;
[self loadTextContentIntoStorage];
}
- (NSData *)dataOfType:(NSString *)typeName error:(NSError **)outError
{
return [self.textStorage.string dataUsingEncoding:NSUTF8StringEncoding];
}
- (BOOL)readFromData:(NSData *)data ofType:(NSString *)typeName error:(NSError **)outError
{
textContentToLoad = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
if (!textContentToLoad) {
*outError = [NSError errorWithDomain:NSCocoaErrorDomain code:NSFileReadUnknownError userInfo:nil];
return NO;
}
[self loadTextContentIntoStorage];
return YES;
}
- (void)loadTextContentIntoStorage
{
if (!self.textStorage || !textContentToLoad)
return;
[self.textStorage beginEditing];
[self.textStorage replaceCharactersInRange:NSMakeRange(0, self.textStorage.length) withString:textContentToLoad];
[textContentToLoad release], textContentToLoad = nil;
}
@end
答案 0 :(得分：2)
当涉及到类型时，你的plist是否正确设置？
似乎NSDocument将[self fileNameExtensionForType:[self autosavingFileType] saveOperation:NSAutosaveElsewhereOperation]的结果传递给stringByAppendingPathExtension:（此处抛出异常的方法）。如果您的应用为此表达式返回nil，则可能会导致此异常。
你可能应该向Apple提交一个错误，但在此期间，请确保你的应用返回非nil的内容。
答案 1 :(得分：0)
将其粘贴到您的文档类（例如Document.m）：
-(NSString*)fileNameExtensionForType:(NSString *)typeName saveOperation: (NSSaveOperationType)saveOperation
{
return @"yourAutosaveExtension";
}
之前，像kperryua说的那样，这种方法没有实现，并且返回了nil。