title: I'm in purpose of hiding UIPickerView below the screen using constraints, can I ignore this debugger message?
body: <p>I want to hide UIPickerView below the screen, in this case 3.5 inch display. after learning about constraint value, finally I know what number should I put for <code>NSLayoutAttributeTop</code>.</p>
  
  <p>here's my complete code :</p>
  
  <pre><code>NSLayoutConstraint *constraint = [NSLayoutConstraint
                                    constraintWithItem:_pickerView
                                    attribute:NSLayoutAttributeTop
                                    relatedBy:NSLayoutRelationEqual
                                    toItem:self.view
                                    attribute:NSLayoutAttributeTop
                                    multiplier:1.0f
                                    constant:416.f];
  
  [self.view addConstraint:constraint];
  </code></pre>
  
  <p>and when I run into my iDevice it works like I expected, except... the debugger console.. it gives me this message :</p>
  
  <pre><code>2013-09-19 12:34:01.850 Constrain2[3546:c07] Unable to simultaneously satisfy constraints.
      Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
  (
      "&lt;NSAutoresizingMaskLayoutConstraint:0x75490d0 h=--&amp; v=--&amp; V:[UIView:0x715a2f0(416)]&gt;",
      "&lt;NSLayoutConstraint:0x7159950 V:[UIPickerView:0x715a030(216)]&gt;",
      "&lt;NSLayoutConstraint:0x71597c0 V:|-(416)-[UIPickerView:0x715a030]   (Names: '|':UIView:0x715a2f0 )&gt;",
      "&lt;NSLayoutConstraint:0x715a7a0 UIPickerView:0x715a030.bottom == UIView:0x715a2f0.bottom&gt;"
  )
  </code></pre>
  
  <p>when I changed the constant value into = 200.f which taken from 416 (superview) - 216 (uipickerview), debugger console is clear. no message there.</p>
  
  <p>is it error message or just a warning? can it be ignored? is it possible to hide that UIPickerView below the screen without having that message appear on debugger console?</p>
  
  <p>it seems that message won't appear when UIPickerView placed properly in its position. that is constant: 200.f</p>
  
  <p>thank you.</p>