NSComparisonPredicate NSDirectPredicateModifier example in Objective C (iOS).

NSComparisonPredicate NSDirectPredicateModifier

NSComparisonPredicateModifier
These constants describe the possible types of modifier for NSComparisonPredicate.

enum {
NSDirectPredicateModifier = 0,
NSAllPredicateModifier,
NSAnyPredicateModifier,
};
typedef NSUInteger NSComparisonPredicateModifier;

Constants
NSDirectPredicateModifier
A predicate to compare directly the left and right hand sides.
NSAllPredicateModifier
A predicate to compare all entries in the destination of a to-many relationship.
The left hand side must be a collection. The corresponding predicate compares each value in the left hand side with the right hand side, and returns NO when it finds the first mismatch—€”or YES if all match.
NSAnyPredicateModifier
A predicate to match with any entry in the destination of a to-many relationship.
The left hand side must be a collection. The corresponding predicate compares each value in the left hand side against the right hand side and returns YES when it finds the first match—or NO if no match is found

NSComparisonPredicate NSDirectPredicateModifier example.

-(NSPredicate *) predicateWithStudyID:(NSString *) aStudyID studyName:(NSString *) aStudyName date:(NSDate *) aDate{
  NSPredicate *p;
  NSMutableArray *preds=[[NSMutableArray alloc] initWithCapacity:1];
  if (aDate != nil) {
    NSExpression *dateKeyEx=[NSExpression expressionForKeyPath:@"studyDate"];
    NSExpression *aDateEx=[NSExpression expressionForConstantValue:aDate];
    NSPredicate *datePred=[NSComparisonPredicate predicateWithLeftExpression:dateKeyEx
                                                             rightExpression:aDateEx
                                                                    modifier:NSDirectPredicateModifier
                                                                        type:NSEqualToPredicateOperatorType
                                                                     options:0];
    [preds addObject:datePred];
  }
  if (![aStudyID isEqualToString:@""]) {
    NSExpression *studyIDKeyEx=[NSExpression expressionForKeyPath:@"studyID"];
    NSExpression *aStudyIDEx=[NSExpression expressionForConstantValue:aStudyID];
    NSPredicate *studyIDPred=[NSComparisonPredicate predicateWithLeftExpression:studyIDKeyEx
                                                                rightExpression:aStudyIDEx
                                                                       modifier:NSDirectPredicateModifier
                                                                           type:NSLikePredicateOperatorType
                                                                        options:NSCaseInsensitivePredicateOption];
    [preds addObject:studyIDPred];
  }
  if (![aStudyName isEqualToString:@""]) {
    NSExpression *studyNameKeyEx=[NSExpression expressionForKeyPath:@"studyName"];
    NSExpression *aStudyNameEx=[NSExpression expressionForConstantValue:aStudyName];
    NSPredicate *studyNamePred=[NSComparisonPredicate predicateWithLeftExpression:studyNameKeyEx
                                                                rightExpression:aStudyNameEx
                                                                       modifier:NSDirectPredicateModifier
                                                                           type:NSLikePredicateOperatorType
                                                                        options:NSCaseInsensitivePredicateOption];
    [preds addObject:studyNamePred];
  }
  p=[NSCompoundPredicate andPredicateWithSubpredicates:preds]; 
  [preds release];
  return p;
}

Example of [NSComparisonPredicate NSDirectPredicateModifier].

NSExpression *left = [NSExpression expressionForKeyPath:@"length"];
NSExpression *right = [NSExpression expressionForConstantValue:[NSNumber numberWithInt:0]];

NSComparisonPredicateModifier modifier = NSDirectPredicateModifier;
NSPredicateOperatorType operator = NSEqualToPredicateOperatorType;

NSPredicate *predicate = [NSComparisonPredicate predicateWithLeftExpression:left rightExpression:right modifier:modifier type:operator options:0];

NSArray *filtered = [myArray filteredArrayUsingPredicate:predicate];

NSComparisonPredicate NSDirectPredicateModifier example.

NSPredicate *nameQuery =
[NSComparisonPredicate predicateWithLeftExpression:[NSExpression expressionForKeyPath:@"s_name"]
                                   rightExpression:[NSExpression expressionForConstantValue:Name]
                                          modifier:NSDirectPredicateModifier
                                              type:NSLikePredicateOperatorType
                                           options:NSCaseInsensitivePredicateOption|NSDiacriticInsensitivePredicateOption];

NSPredicate *regNoQuery =
[NSComparisonPredicate predicateWithLeftExpression:[NSExpression expressionForKeyPath:@"s_regno"]
                                   rightExpression:[NSExpression expressionForConstantValue:RegNo]
                                          modifier:NSDirectPredicateModifier
                                              type:NSEqualToPredicateOperatorType
                                           options:0];

NSPredicate *query = [NSCompoundPredicate andPredicateWithSubpredicates:@[nameQuery,regNoQuery]];

End of NSComparisonPredicate NSDirectPredicateModifier example article.