Question

当我异步执行ftp请求时遇到问题，我试着清楚地描述确切的问题：

- (void)viewDidLoad
{
    [super viewDidLoad];

    //I want to do a ftpListRequst in the background here
    dispatch_async(dispatch_get_global_queue(0, 0), ^{

        NewFTPListService *nfl = [[NewFTPListService alloc] initWithFtpPath:@"ftp://root:@10.0.0.3/"];

        [nfl listDirectoryContents];

        [nfl release];

    }); 

    //other main thread code
}

- (NSArray *) listDirectoryContents
{   
    [_listDir start];

    //What I want to do here is to wait until the ftp request finish
    while (!self.isFinish) {
        [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
    }

    NSLog(@"Request Finish!");

    return self.result;
}

-(void) start {
    ......
    self.streamInfo->readStream.delegate = self;
    [self.streamInfo->readStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [self.streamInfo->readStream open];

    //If request is blocked (may be the server is not avaliable), after a specific time, this block will be called
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, kWRDefaultTimeout * NSEC_PER_SEC), dispatch_get_current_queue(), ^{       
        [self.delegate requestFailed:self];
        [self destroy];
    });

}

成功完成请求后，将调用此方法：

-(void) requestCompleted:(WRRequest *) request{

    self.isSucess = YES;
    self.isFinish = YES;
}

此方法将在＆＃34; dispatch_after＆＃34;中调用。块

-(void) requestFailed:(WRRequest *) request{
    self.isSucess = NO;
    self.isFinish = YES; 
}

当成功完成后，我会看到打印＆＃34;请求完成！＆＃34;。当请求被阻止且＆＃34; dispatch_after＆＃34;调用块，然后＆＃34; requestFailed＆＃34;方法被调用，但我没有看到打印＆＃34;请求完成！＆＃34;。似乎程序在某种程度上停留在while循环中（循环没有运行，代码也没有运行）。

更重要的是，如果我同步运行程序：

- (void)viewDidLoad
    {
        [super viewDidLoad];

        NewFTPListService *nfl = [[NewFTPListService alloc] initWithFtpPath:@"ftp://root:@10.0.0.3/"];

        [nfl listDirectoryContents];

        [nfl release];
    }

即使请求失败，我也能成功看到打印＆＃34;请求完成！＆＃34;。我想知道为什么会发生这种情况以及如何解决这个问题，这样我就可以在请求失败时成功运行程序。谢谢！

Answer 1

您好，只需通过performSelector

调用此方法

[nfl listDirectoryContents];

或在viewDidAppear方法中调用此方法。

请求异步ftp请求时程序停滞不前

1 个答案: