Objective-C Searching and Sorting with NSPredicate

sorting.m

/*
 * File: sorting.m
 * Author: Chad Armstrong
 * Date: 22 September 2014
 * To compile: gcc -g -Wall -framework Foundation -o sorting sorting.m
 */

#import <Foundation/Foundation.h>

void printByAge(NSArray *people);
void printByName(NSArray *people);
void printNickNames(NSArray *people);
void printSimpsons(NSArray *people);
void findPersonOfAge(NSArray *people, int age);

int main (int argc, const char *argv[])
{
	NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
	
	NSArray *people = @[@{@"firstname":@"Homer", @"lastname":@"Simpson", @"age":@(40)},
	@{@"firstname":@"Marjorie", @"lastname":@"Simpson", @"age":@(37), @"nickname":@"Marge"},
	@{@"firstname":@"Abraham", @"lastname":@"Simpson", @"age":@(83), @"nickname":@"Grandpa"},
	@{@"firstname":@"Bart", @"lastname":@"Simpson", @"age":@(10), @"nickname":@"El Barto"},
	@{@"firstname":@"Lisa", @"lastname":@"Simpson", @"age":@(8)},
	@{@"firstname":@"Margaret", @"lastname":@"Simpson", @"age":@(1), @"nickname":@"Maggie"},
	@{@"firstname":@"Charles", @"lastname":@"Burns", @"age":@(104), @"nickname":@"Monty"},
	@{@"firstname":@"Herschel", @"lastname":@"Krustofsky", @"age":@(54), @"nickname":@"Krusty"}];
	
	printByAge(people);
	printByName(people);
	printNickNames(people);
 	printSimpsons(people);
 	findPersonOfAge(people, 83);
 	findPersonOfAge(people, 943);
	
	[pool release];
	
	return (EXIT_SUCCESS);
}

void printByAge(NSArray *people) {

	NSSortDescriptor *ageDescriptor = [[NSSortDescriptor alloc] initWithKey:@"age" ascending:YES];

	NSArray *sortedNames = [people sortedArrayUsingDescriptors:@[ageDescriptor]];
	NSLog(@"NAMES SORTED BY AGE (LOW TO HIGH)"); 
	for (NSDictionary *person in sortedNames) {
		NSLog(@"%@ %@ (%@)", person[@"firstname"], person[@"lastname"], person[@"age"]);
	}
	NSLog(@"-------------");
}

void printByName(NSArray *people) {

	NSSortDescriptor *lastnameDescriptor = [[NSSortDescriptor alloc] initWithKey:@"lastname" ascending:YES];
	NSSortDescriptor *firstnameDescriptor = [[NSSortDescriptor alloc] initWithKey:@"firstname" ascending:YES];

	NSArray *sortedeNames = [people sortedArrayUsingDescriptors:@[lastnameDescriptor, firstnameDescriptor]];
	NSLog(@"SORTED NAMES"); 
	for (NSDictionary *person in sortedeNames) {
		NSLog(@"%@, %@", person[@"lastname"], person[@"firstname"]);
	}
	NSLog(@"-------------");
}

void printNickNames(NSArray *people) {

	NSPredicate *nicknamesPredicate = [NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) {
		return ([(NSDictionary *)evaluatedObject objectForKey:@"nickname"] != nil);
	}];
	
	NSArray *nicknames = [people filteredArrayUsingPredicate:nicknamesPredicate];

	NSLog(@"CHARACTERS WITH NICKNAMES");
	for (NSDictionary *person in nicknames) {
		NSLog(@"%@ \"%@\" %@", person[@"firstname"], person[@"nickname"], person[@"lastname"]);
	}
	NSLog(@"-------------");
}

void printSimpsons(NSArray *people) {

	NSPredicate *isASimpsonPredicate = [NSPredicate predicateWithFormat: @"lastname == %@", @"Simpson"];
	NSArray *simpsons = [people filteredArrayUsingPredicate:isASimpsonPredicate];
	NSLog(@"SIMPSON CHARACTERS");
	for (NSDictionary *person in simpsons) {
		NSLog(@"%@ %@", person[@"firstname"], person[@"lastname"]);
	}
}

void findPersonOfAge(NSArray *people, int age) {

    NSPredicate *predicateExists = [NSPredicate predicateWithFormat: @"age == %d", age];
    NSUInteger index = [people indexOfObjectPassingTest: ^(id obj, NSUInteger idx, BOOL *stop) {
                            return [predicateExists evaluateWithObject:obj];
                        }];
    
    NSLog(@"-------------");
    if (index == NSNotFound) {
        NSLog(@"No Simpsons character is of age %d", age);
    } else {
    	NSDictionary *person = [people objectAtIndex:index];
        NSLog(@"%@ %@ is %d years old", person[@"firstname"], person[@"lastname"], age);
    }
    
}