iphone - UIDocumentInteractionController presentPreviewAnimated : returning NO and not showing preview

Question

我已经尝试了所有我能想到的方法，但它仍然响应“否”，Apple 也没有任何提示。

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"finished!");

    NSString *tempString = [NSString stringWithFormat:@"file://%@%@", NSTemporaryDirectory(), [[NSProcessInfo processInfo] globallyUniqueString]];
    NSURL *tempURL = [NSURL URLWithString:tempString];
    [receivedData writeToURL:tempURL atomically:YES];

    NSLog(@"tempURL is written!");

    UIDocumentInteractionController *interactionController = [UIDocumentInteractionController interactionControllerWithURL:tempURL];
    interactionController.delegate = self;
    [interactionController retain];
    NSLog(@"--- %i", [interactionController presentPreviewAnimated:YES]);
    NSLog(@"presented preview");

    [connection release];
    [receivedData release];
}

- (UIViewController*)documentInteractionControllerViewControllerForPreview:(UIDocumentInteractionController *)controller
{
    NSLog(@"asdf");
    UIViewController *viewController = [[[UIViewController alloc] init] autorelease];
    [self.navigationController pushViewController:viewController animated:YES];
    return viewController;
}

Answer 1

1) 您确信您打开的文件符合犹太洁食标准吗？如果不是，那么返回 NO 将是可以期待的事情

2) 我对您的委托(delegate)方法感到困惑。本方法很乐意自行将推送到导航 Controller 上。如果您改为使用此代码，您会更好吗？ (请参阅 docs 了解基本原理。)

- (UIViewController *) documentInteractionControllerViewControllerForPreview: (UIDocumentInteractionController *) controller
{
    return [self navigationController];
}