Playing With Array methods.

ArrayMethods

#import "Collections.h"

@implementation Collections

//sorts the array in ascending order
-(NSArray *)sortArrayAsc:(NSArray *)array
{
    return [array sortedArrayUsingSelector:@selector(compare:)];
}

//sorts the array in descending order
-(NSArray *)sortArrayDesc:(NSArray *)array
{
    NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"self" ascending:NO];
    
    return [array sortedArrayUsingDescriptors:[NSArray arrayWithObjects:sortDescriptor, nil]];
}

//swaps index 1 and 2
-(NSArray *)swapElements:(NSArray *)array
{
    NSMutableArray *result = [[NSMutableArray alloc] initWithArray:array];
    [result exchangeObjectAtIndex:1 withObjectAtIndex:2];
    return result;
}

//reverses the array
-(NSArray *)reverseArray:(NSArray *)array
{
    return [[array reverseObjectEnumerator] allObjects];
}

//replaces 3rd element of each string with $ sign
-(NSArray *)keshaMaker:(NSArray *)array
{
    NSMutableArray *result = [[NSMutableArray alloc] init];
    
    for (NSString *object in array){
        
        NSString *newString = [object stringByReplacingCharactersInRange:NSMakeRange(2, 1) withString:@"$"];
        [result addObject:newString];
    }
    return result;
}

//sorts array into two arrays, one greater and one less than 10, creates a dict with both
-(NSDictionary *)greaterAndLessThan10:(NSArray *)array
{
    NSMutableArray *greater_than_10 = [[NSMutableArray alloc] init];
    NSMutableArray *less_than_10 = [[NSMutableArray alloc] init];
    
    for (NSNumber *item in array){
        
        if ([item integerValue] > 10){
            
            [greater_than_10 addObject:item];
        }
        else {
            
            [less_than_10 addObject:item];
        }
    }
    return @{@"greater_than_10": greater_than_10, @"less_than_10": less_than_10};
}

//creates an array of winners from people dictionary
-(NSArray *)findWinners:(NSDictionary *)peopleDictionary
{
    return [peopleDictionary allKeysForObject:@"winner"];
}

//returns an array with all words that contain 'a'
-(NSArray *)findA:(NSArray *)array
{
    NSPredicate *aPredicate = [NSPredicate predicateWithFormat:@"SELF beginsWith[c] 'a'"];
    
    return [array filteredArrayUsingPredicate:aPredicate];
}

//returns the sum of the values in the array
-(NSInteger)sumArray:(NSArray *)array
{
    NSNumber *sum = [array valueForKeyPath:@"@sum.self"];
    return [sum integerValue];
}

//returns an array that added 's' to each word in array except for 2nd element in the array
-(NSArray *)addS:(NSArray *)array
{
    NSMutableArray *result = [[NSMutableArray alloc] init];
    
    for (int x = 0; x < array.count; x++){
        
        NSString *currentItem = array[x];
        
        if (x == 1) {
            [result addObject:currentItem];
        } else {
            [result addObject:[NSString stringWithFormat:@"%@s", currentItem]];
        }
    }
    return result;
}

//returns a dictionary with word keys and # of word occurences in story as values
-(NSDictionary *)countWordsInStory:(NSString *)story
{
    NSArray *storyWords = [story componentsSeparatedByString:@" "];
    NSMutableDictionary *wordDictionary = [[NSMutableDictionary alloc] init];
    
    for (NSString *word in storyWords){
        if (wordDictionary[word]){
            NSInteger count = [wordDictionary[word] integerValue];
            count++;
            wordDictionary[word] = [NSNumber numberWithInteger:count];
        } else {
            wordDictionary[word] = @1;
        }
    }
    return wordDictionary;
}

//creates a dictionary with artist keys and values of songs related to the artist
-(NSDictionary *)organizeSongsByArtist:(NSArray *)array
{
    NSMutableDictionary *artists = [[NSMutableDictionary alloc] init];
    
    for (NSString *jam in array){
        NSArray *splitJam = [jam componentsSeparatedByString:@" - "];
        NSString *artist = splitJam[0];
        NSString *song = splitJam[1];
        
        if (artists[artist]){
            NSMutableArray *artistTracks = artists[artists];
            [artistTracks addObject:song];
        } else {
            artists[artist] = [[NSMutableArray alloc] initWithObjects:song, nil];
        }
    }
    return artists;
}


@end