@property int isTyping;

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {

    [self startTyping];

    [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(stopTyping) object:nil];
    [self performSelector:@selector(stopTyping) withObject:nil afterDelay:0.5];

    return YES;
}

- (void)startTyping {

    if (self.isTyping==0) {
        self.isTyping=1;
        [self sendTypingStartData];
    }
}

- (void)stopTyping {
    self.isTyping=0;
    [self sendTypingStopData];
}