Sunday, May 12, 2013

NSInputStream getBuffer length example ios

getBuffer: length:

Returns by reference a pointer to a read buffer and, by reference, the number of bytes available, and returns a Boolean value that indicates whether the buffer is available.
- (BOOL)getBuffer:(uint8_t **)buffer length:(NSUInteger *)len
Upon return, contains a pointer to a read buffer. The buffer is only valid until the next stream operation is performed.
Upon return, contains the number of bytes available.
Return Value( NSInputStream getBuffer length example )
YES if the buffer is available, otherwise NO.
Subclasses of NSInputStream may return NO if this operation is not appropriate for the stream type.
( NSInputStream getBuffer length example )
uint8_t *buf1;
        unsigned int numBytes1;
        if ([((NSInputStream *) stream) getBuffer: &buf length: &numBytes]) {
            NSLog(@"\t\tBytes are in the buffer before Op.");

        uint8_t buffer[BUFFER_SIZE];
        int len = [((NSInputStream *) stream) read: buffer 
                                         maxLength: BUFFER_SIZE];

        uint8_t *buf2;
        unsigned int numBytes2;
        if ([((NSInputStream *) stream) getBuffer: &buf2 length: &numBytes2]) {
            NSLog(@"\t\tBytes in the buffer after Op.");
( NSInputStream getBuffer length example )
- (void)stream:(NSInputStream *)iStream handleEvent:(NSStreamEvent)event {
    BOOL shouldClose = NO;
    switch(event) {
        case  NSStreamEventEndEncountered:
            shouldClose = YES;
            // If all data hasn't been read, fall through to the "has bytes" event
            if(![iStream hasBytesAvailable]) break;
        case NSStreamEventHasBytesAvailable: ; // We need a semicolon here before we can declare local variables
            uint8_t *buffer;
            NSUInteger length;
            BOOL freeBuffer = NO;
            // The stream has data. Try to get its internal buffer instead of creating one
            if(![iStream getBuffer:&buffer length:&length]) {
                // The stream couldn't provide its internal buffer. We have to make one ourselves
                buffer = malloc(BUFFER_LEN * sizeof(uint8_t));
                freeBuffer = YES;
                NSInteger result = [iStream read:buffer maxLength:BUFFER_LEN];
                if(result < 0) {
                    // error copying to buffer
                length = result;
            // length bytes of data in buffer
            if(freeBuffer) free(buffer);
        case NSStreamEventErrorOccurred:
            // some other error
            shouldClose = YES;
    if(shouldClose) [iStream close];