objective-c – NSStream不发送所有数据

我的情况很奇怪：
我几乎使用了示例“SimpleFTPSample”(类型的一些小变体[self.networkStream setProperty：(id)kCFBooleanFalse forKey：(NSString *)kCFStreamPropertyFTPAttemptPersistentConnection];以避免保持连接活动WiFi / 3G)执行传输操作FTP文件但是,尽管没有任何类型的错误,如果您使用ftp站点,则下载的文件已损坏：要解决此问题,只需添加一个睡眠(3)！必须在[self.networkStream close]之前执行此功能(睡眠);
警告：如果我改变了ftp站点,没有“sleep(3)”就没问题！

我什么都不懂……感谢任何类型的援助

我附上了我的示例代码.

- (void)_startSend
{
BOOL                success;
NSURL *             url;
CFWriteStreamRef        ftpStream;

assert(self.networkStream == nil);      // don't tap receive twice in a row!
assert(self.fileStream == nil);         // ditto
assert(self.filePath == nil);           // self.filePath rappresenta il percorso del file da inviare

self.attendere.hidden = FALSE;

// First get and check the URL.
defaults = [NSUserDefaults standardUserDefaults];

NSString * Cartella_ZIP = [[defaults objectForKey:kIndirizzoIpUploadKey] 
                            stringByAppendingString:self.Nome_File_da_Inviare];

url = [[iSalesAgentAppDelegate sharedAppDelegate] smartURLForString:Cartella_ZIP];
success = (url != nil);

// If the URL is bogus,let the user know.  Otherwise kick off the connection.

if ( ! success) {
    self.statuslabel.text = @"Indirizzo FTP non valido!";
} else {
    NSLog(@"nome file %@",self.Nome_File_da_Inviare);
    self.filePath = [self.Cartella_Lavoro stringByAppendingPathComponent:self.Nome_File_da_Inviare];
    assert(self.filePath != nil);

    self.fileStream = [NSInputStream inputStreamWithFileAtPath:self.filePath];
    assert(self.fileStream != nil);

    [self.fileStream open];

    // Open a CFFTPStream for the URL.
    ftpStream = CFWriteStreamCreateWithFTPURL(NULL,(__bridge CFURLRef) url);
    assert(ftpStream != NULL);

    self.networkStream = (__bridge NSOutputStream *) ftpStream;   
    success = [self.networkStream setProperty:[defaults objectForKey:kUsernameFtpKey] forKey:(id)kCFStreamPropertyFTPUserName];
    assert(success);
    success = [self.networkStream setProperty:[defaults objectForKey:kPasswordFtpKey] forKey:(id)kCFStreamPropertyFTPPassword];
    assert(success);

    [self.networkStream setProperty:(id)kCFBooleanFalse forKey:(NSString *)kCFStreamPropertyFTPAttemptPersistentConnection];

    self.networkStream.delegate = self;
    [self.networkStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

    [self.networkStream open];

    CFRelease(ftpStream);

    [self _sendDidStart];        
   }
 }
- (void)_stopSendWithStatus:(NSString *)statusString {
if (self.networkStream != nil) {
    [self.networkStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    self.networkStream.delegate = nil;
    [self.networkStream close];
    self.networkStream = nil;
}

if (self.fileStream != nil) {
    [self.fileStream close];
    self.fileStream = nil;
}
[self _sendDidStopWithStatus:statusString];
}

- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode
{
assert(aStream == self.networkStream);
NSString * stringa_byte_letti =nil;
NSString * stringa_filesize =nil;
NSNumber * number = nil; 

self.filesize = [[[NSFileManager defaultManager] attributesOfItemAtPath:self.filePath error:nil] fileSize];

NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc] init]; 
[numberFormatter setNumberStyle:kCFNumberFormatterDecimalStyle]; 
[numberFormatter setGroupingSeparator:@"."];     

switch (eventCode) {
    case NSStreamEventOpenCompleted: {
        // Added: Finally get filesize
        [self _updateStatus:@"Aperta Connessione"];
        filesize = 0; byte_scritti = 0;
    } break;
    case NSStreamEventHasBytesAvailable: {
        [self _stopSendWithStatus:@"Network write error"];
        assert(NO);     // should never happen for the output stream
    } break;
    case NSStreamEventHasSpaceAvailable: {
        [self _updateStatus:@"Invio Ordine..."];

        if (self.bufferOffset == self.bufferLimit) {
            NSInteger   bytesRead;
            bytesRead = [self.fileStream read:self.buffer maxLength:kSendBufferSize];

            if (bytesRead == -1) {
                [self _stopSendWithStatus:@"File read error"];
            } else if (bytesRead == 0) {
                sleep(3);
                [self _stopSendWithStatus:nil];
            } else {
                self.bufferOffset = 0;
                self.bufferLimit  = bytesRead;
            }
        }

        // If we're not out of data completely,send the next chunk.

        if (self.bufferOffset != self.bufferLimit) {
            NSInteger   bytesWritten;
            bytesWritten = [self.networkStream write:&self.buffer[self.bufferOffset] maxLength:self.bufferLimit - self.bufferOffset];
            assert(bytesWritten != 0);
            byte_scritti += bytesWritten;
            if (bytesWritten == -1) {
                [self _stopSendWithStatus:@"Network write error"];
            } else {
                self.bufferOffset += bytesWritten;
            }
        }

        number = [NSNumber numberWithDouble:byte_scritti]; 
        stringa_byte_letti = [numberFormatter stringForObjectValue:number]; 
        number = [NSNumber numberWithInteger:self.filesize]; 
        stringa_filesize = [numberFormatter stringForObjectValue:number]; 
        [self _updateStatus:[NSString stringWithFormat:@"Invio File nr. %i di %i: Totale byte %@ - byte scritti : %@",[self.numero_file_da_inviare intValue]+1,[Array_FileZip count],stringa_filesize,stringa_byte_letti ]];

        // Pull some data off the network.
        NSNumber * percentuale_progress = [NSNumber numberWithFloat: (float)byte_scritti / (float)self.filesize];
        [self performSelectorOnMainThread:@selector(Aggiorna_ProgressBar:) withObject:percentuale_progress waitUntilDone:YES];        

    } break;
    case NSStreamEventErrorOccurred: {
        [self _stopSendWithStatus:@"File Dati non trovato!"];
    } break;
    case NSStreamEventEndEncountered: {
        // evento ignorato
    } break;
    default: {
        [self _stopSendWithStatus:@"Network write error"];
        assert(NO);
    } break;
}   
}