'UIDocumentInteractionController: invalid scheme (null).  Only the file scheme is supported.'

我使用下面的代码：

- (void) webServiceController:(WebServiceController *)webServiceController returnedArray:(NSMutableArray *)array {
    if ([webServiceController.webRequest isEqualToString: @"generateExcelFileForEmployee"]) {
        // start previewing the document at the current section index
        NSString *link = [[NSString stringWithString:array[0]] stringByReplacingOccurrencesOfString:@"AdminFunctions.PHP" withString:@"AdminFunctions.xls"];
        link = [[[link stringByReplacingOccurrencesOfString:@"\\" withString:@""]stringByReplacingOccurrencesOfString:@"/public/sites/" withString:@"http://"]stringByReplacingOccurrencesOfString:@"\"\\\"" withString:@""];
        NSLog(@"%@",link);
        NSData *urlData = [NSData dataWithContentsOfURL:[NSURL URLWithString:link]];

        NSArray   *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
        NSString  *documentsDirectory = [paths objectAtIndex:0];

        NSString  *filePath = [NSString stringWithFormat:@"%@/%@",documentsDirectory,@"AdminFunctions.xls"];

        BOOL isWriteSuccess = [urlData writeToFile:filePath atomically:YES];
        NSLog(@"%@",filePath);

        if(isWriteSuccess) //success
        {
            file = [NSURL fileURLWithPath:filePath];

            self.fileView = [self setupControllerWithURL:file usingDelegate:self];

            [self.fileView presentPreviewAnimated:YES];
        }
        else
        {
           NSLog(@"file not written");
        }
    }
}

- (UIDocumentInteractionController *) setupControllerWithURL: (NSURL*) fileURL usingDelegate: (id <UIDocumentInteractionControllerDelegate>) interactionDelegate {

    UIDocumentInteractionController *interactionController =
    [UIDocumentInteractionController interactionControllerWithURL: fileURL];
    interactionController.delegate = interactionDelegate;

    return interactionController;
}

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

这两种方法都在我想呈现预览的viewcontroller中实现.我知道很难,我得到的数据在urlData对象,因为当我放入断点,控制台说,它包含6144字节,这正是要下载的文件的大小.

我一直在寻找这个安静的一段时间,但我似乎无法弄清楚如何解决这个问题.我已经尝试将link对象作为documentInteractionController的源,但是错误更改为：

'UIDocumentInteractionController: invalid scheme (http).  Only the file scheme is supported.'

任何关于如何克服这个问题的意见将被高度赞赏