Category to turn @[ @"a", @"b", @"c" ] into @"a, b and c". So useful I must have it in three different apps.

NSArray+Conjunction.h

//
//  NSArray+Conjunction.h
//  Typesetter
//
//  Created by Brent Royal-Gordon on 2/11/12.
//  Copyright (c) 2012 Architechies. All rights reserved.
//



@interface NSArray (Conjunction)

@property (readonly) NSString * conjunction;

@end

@interface NSSet (Conjunction)

@property (readonly) NSString * conjunction;

@end

NSArray+Conjunction.m

//
//  NSArray+Conjunction.m
//  Typesetter
//
//  Created by Brent Royal-Gordon on 2/11/12.
//  Copyright (c) 2012 Architechies. All rights reserved.
//

#import "NSArray+Conjunction.h"

@implementation NSArray (Conjunction)

- (NSString *)conjunction {
    BOOL last = YES;
    NSString * accumulator;
    
    for(NSString * item in self.reverseObjectEnumerator) {
        if(!accumulator) {
            accumulator = item;
        }
        else if(last) {
            accumulator = [NSString stringWithFormat:@"%@ and %@", item, accumulator];
            last = NO;
        }
        else {
            accumulator = [NSString stringWithFormat:@"%@, %@", item, accumulator];
        }
    }
    
    return accumulator;
}

@end

@implementation NSSet (Conjunction)

- (NSString *)conjunction {
    NSArray * array = [self.allObjects sortedArrayUsingSelector:@selector(localizedStandardCompare:)];
    return array.conjunction;
}

@end