ios – NSInputStream停止运行,有时会抛出EXC_BAD_ACCESS

(更新)这是一个简单的问题：在iOS中,我想要读取一个大文件,对它进行一些处理(在这种特殊情况下编码为Base64 string()并保存到设备上的临时文件,我设置一个从文件读取的NSInputStream,然后在

(void)stream:(Nsstream *)stream handleEvent:(NsstreamEvent)eventCode

我在做大部分的工作.由于某些原因,有时我可以看到NSInputStream刚停止工作.我知道,因为我有一条线

NSLog(@"stream %@ got event %x",stream,(unsigned)eventCode);

在(void)stream：(Nsstream *)的开头处理streamEvent：(NsstreamEvent)eventCode,有时候我会看到输出

stream <__NSCFInputStream: 0x1f020b00> got event 2

(对应于事件NsstreamEventHasBytesAvailable),然后再没有.不是事件10,对应于NsstreamEventEndEnmitted,不是错误事件,没有！还有时候我甚至得到一个EXC_BAD_ACCESS异常,我现在不知道如何调试.任何帮助将不胜感激.

这是实现.当我点击“提交”按钮时,一切都会启动,这会触发：

- (IBAction)submit:(id)sender {     
    [p_spinner startAnimating];    
    [self performSelector: @selector(sendData)
           withObject: nil
           afterDelay: 0];   
}

这里是sendData：

-(void)sendData{
    ...
    _tempFilePath = ... ;
    [[NSFileManager defaultManager] createFileAtPath:_tempFilePath contents:nil attributes:nil];
    [self setUpStreamsForInputFile: [self.p_mediaURL path] outputFile:_tempFilePath];
    [p_spinner stopAnimating];
    //Pop back to prevIoUs VC
    [self.navigationController popViewControllerAnimated:NO] ;
}

这里是上面提到的setUpStreamsForInputFile：

- (void)setUpStreamsForInputFile:(Nsstring *)inpath outputFile:(Nsstring *)outpath  {
    self.p_iStream = [[NSInputStream alloc] initWithFileAtPath:inpath];
    [p_iStream setDelegate:self];
    [p_iStream scheduleInRunLoop:[NSRunLoop currentRunLoop]
                           forMode:NSDefaultRunLoopMode];
    [p_iStream open];   
}

最后,这是大多数逻辑发生的地方：

- (void)stream:(Nsstream *)stream handleEvent:(NsstreamEvent)eventCode {

    NSLog(@"stream %@ got event %x",(unsigned)eventCode);

    switch(eventCode) {
        case NsstreamEventHasBytesAvailable:
        {
            if (stream == self.p_iStream){
                if(!_tempMutableData) {
                    _tempMutableData = [NSMutableData data];
                }
                if ([_streamdata length]==0){ //we want to write to the buffer only when it has been emptied by the output stream
                    unsigned int buffer_len = 24000;//read in chunks of 24000
                    uint8_t buf[buffer_len];
                    unsigned int len = 0;
                    len = [p_iStream read:buf maxLength:buffer_len];
                    if(len) {
                        [_tempMutableData appendBytes:(const void *)buf length:len];
                        Nsstring* base64encData = [Base64 encodeBase64WithData:_tempMutableData];
                        _streamdata = [base64encData dataUsingEncoding:NSUTF8StringEncoding];  //encode the data as Base64 string
                        [_tempFileHandle writeData:_streamdata];//write the data
                        [_tempFileHandle seekToEndOfFile];// and move to the end
                        _tempMutableData = [NSMutableData data]; //reset mutable data buffer 
                        _streamdata = [[NSData alloc] init]; //release the data buffer
                    } 
                }
            }
            break;
        case NsstreamEventEndEncountered:
        {
            [stream close];
            [stream removeFromrunLoop:[NSRunLoop currentRunLoop]
                              forMode:NSDefaultRunLoopMode];
            stream = nil;
            //do some more stuff here...
            ...
            break;
        }
        case NsstreamEventHasspaceAvailable:
        case NsstreamEventOpenCompleted:
        case NsstreamEventNone:
        {
           ...
        }
        }
        case NsstreamEventErrorOccurred:{
            ...
        }
    }
}

注意：当我第一次发布时,我的错误印象是这个问题与使用GCD有关.根据Rob在下面的回答,我删除了GCD代码,问题依然存在.

dispatch_queue_t queue = dispatch_get_global_queue(disPATCH_QUEUE_PRIORITY_DEFAULT,0);
 dispatch_async(queue,^{ 
     // your background code

     //end of your code

     [[NSRunLoop currentRunLoop] run]; // start a run loop,look at the next point
});

[[NSRunLoop currentRunLoop] run]; // note: this method never returns,so it must be THE LAST LINE of your dispatch

- (void)setUpStreamsForInputFile:(Nsstring *)inpath outputFile:(Nsstring *)outpath  {
    self.p_iStream = [[NSInputStream alloc] initWithFileAtPath:inpath];
    [p_iStream setDelegate:self];

    // here: change the queue type and use a background queue (you can change priority)
    dispatch_queue_t queue = dispatch_get_global_queue(disPATCH_QUEUE_PRIORITY_DEFAULT,0);
    dispatch_async(queue,^ {
        [p_iStream scheduleInRunLoop:[NSRunLoop currentRunLoop]
                       forMode:NSDefaultRunLoopMode];
        [p_iStream open];

        // here: start the loop
        [[NSRunLoop currentRunLoop] run];
        // note: all code below this line won't be executed,because the above method NEVER returns.
    });    
}

- (void)stream:(Nsstream *)stream handleEvent:(NsstreamEvent)eventCode {}