我正在制作一个文本编辑器应用程序,将其每个文档存储为 NSFileWrapper 目录,文档文本和文档标题作为目录中的单独文件。我希望contents
部分loadFromContents: (id) contents
是 NSFileWrapper,但事实并非如此。我的代码如下(它属于 UIDocument 的子类):
// loads document data to application data model
- (BOOL) loadFromContents:(id)contents ofType:(NSString *)typeName error:(NSError *__autoreleasing *)outError {
// from the contents, extract it so that we have the properties initialized
self.fileWrapper = (NSFileWrapper *) contents;
NSLog(@"%@", [contents class]); //** returns NSConcreteData
// get the fileWrapper's children
NSDictionary *contentsOfFileWrapper = [contents fileWrappers];
// assign things to the document!
// can also be done lazily through getters
self.text = [contentsOfFileWrapper objectForKey:TEXT_KEY];
self.title = [contentsOfFileWrapper objectForKey:TITLE_KEY];
if ([self.delegate respondsToSelector:@selector(noteDocumentContentsUpdated:)]){
[self.delegate noteDocumentContentsUpdated:self];
}
return YES;
}
当我尝试调用此方法时,出现此错误:
*** 由于未捕获的异常“NSInvalidArgumentException”而终止应用程序,原因:“-[NSConcreteData fileWrappers]:无法识别的选择器发送到实例 0x9367150”
contentsForType:
如果有帮助,以下是我的功能:
- (id) contentsForType:(NSString *)typeName error:(NSError *__autoreleasing *)outError {
if (!self.fileWrapper) {
self.fileWrapper = [[NSFileWrapper alloc] initDirectoryWithFileWrappers:nil];
}
NSDictionary *childrenFileWrappers = [self.fileWrapper fileWrappers];
// now if we have a text but it is not represented, in the file wrapper, put it in. Same with the images.
if ([childrenFileWrappers objectForKey:TEXT_KEY] == nil && self.text != nil) {
NSData *textData = [self.text dataUsingEncoding:kCFStringEncodingUTF16];
NSFileWrapper *textFileWrapper = [[NSFileWrapper alloc] initRegularFileWithContents:textData];
[textFileWrapper setPreferredFilename:TEXT_KEY];
[self.fileWrapper addFileWrapper:textFileWrapper];
}
if ([childrenFileWrappers objectForKey:TITLE_KEY] == nil && self.title != nil) {
NSData *titleData = [self.title dataUsingEncoding:kCFStringEncodingUTF16];
NSFileWrapper *titleFileWrapper = [[NSFileWrapper alloc] initRegularFileWithContents:titleData];
[titleFileWrapper setPreferredFilename:TITLE_KEY];
[self.fileWrapper addFileWrapper:titleFileWrapper];
}
return self.fileWrapper;
}
谢谢!