- (void)viewDidLoad
{
  ...
  SCClassDefinition *adresseClassDef = [SCClassDefinition definitionWithEntity:...];
  adresseClassDef.uiElementDelegate = self;  // enable SCTableViewCellDelegate methods
  SCPropertyDefinition *streetPropertyDef = [adresseClassDef propertyDefinitionWithName:@"street"];
  streetPropertyDef.autoValidate = FALSE;
  ...
}
 
// Make sure your VC conforms to the SCTableViewCellDelegate protocol for
// this method to get called
- (BOOL)valueIsValidForCell:(SCTableViewCell *)cell
{
  if([cell isKindOfClass:[SCTextFieldCell class]])
  {
    NSString *street = ((SCTextFieldCell *)cell).textField.text;
 
 
    // now here you should load all your Core Data adresse entities in an array and
    // compare their street attributes to "street". If street is found within
    // the adresses, you should return FALSE, else return TRUE.
    // Important Note: This can be much more optimized if you cache an array of 
    // streets beforehand instead of loading all the entities each time the street
    // text is validated.
  } 
}