如何打开下载的PDF文件？

Question

我有以下代码来下载PDF文件：

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    if(connection != theConnection) return;

    NSFileManager * FM = [NSFileManager defaultManager];
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);


    NSString *documentsDirectory = [paths objectAtIndex:0];
    saveDownLoad = documentsDirectory;

    NSString * bookNameInfo = [NSString stringWithFormat:@"%@.%@",@"BookName",@"pdf"];


    NSString *downloadPath = [documentsDirectory stringByAppendingPathComponent:bookNameInfo];
    [[Utility sharedSingleton] setBookDirectURL:downloadPath];


    if([FM createFileAtPath:downloadPath contents:downLoadData attributes:nil])
    {
        [downLoadView close];
    UIAlertView * saveAlert = [[UIAlertView alloc] initWithTitle:@"DownLoad Success" 
                        message:@"DownLoad The end ."   
                        delegate:self
                 cancelButtonTitle:nil 
            otherButtonTitles:@"OK",@"open PDF",nil];
    [saveAlert show];
    [saveAlert release];
    [self.view removeFromSuperview];
    }

    if(downLoadData) 
    {
        [downLoadData release];
    }
}


and if(click button) => open PDF File (use other app)


-(void)showSelectMenu
{


    NSString * stringText = [[NSBundle mainBundle] pathForResource:@"BookName" ofType:@"pdf"];
    NSURL *url = [NSURL fileURLWithPath:stringText];
    UIDocumentInteractionController* docController = [UIDocumentInteractionController interactionControllerWithURL:url];
    docController.delegate = self;
    [docController retain];


    [docController presentOpenInMenuFromRect:CGRectMake(0.0, 144.0, 100.0, 200.0) inView:self.view animated:YES];
}

但该程序无法显示 PDF文件。

如果播放showSelectMenu关闭程序;;

为什么关机程序？我不知道;;