title: self.viewDelegate = 0x0 why?
body: <p>In the following code the
  <code>self.viewDelegate</code> is <code>0x0</code> and I don't know how to solve
  this problem. Should I have to go to the interface Builder?</p>
  
  <pre><code>- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
      UITouch *touch = [[event allTouches] anyObject]; 
      if ([touch tapCount] == 2) {
          if ([self.viewDelegate respondsToSelector:@selector(openFlowView:doubleTapOnIndex:itemView:)])
              [self.viewDelegate openFlowView:self doubleTapOnIndex:selectedCoverView.number itemView:selectedCoverView];
          }
  </code></pre>