NSString+Split

NSString+Split.h

#import <Foundation/Foundation.h>

@interface NSString (Split)

- (NSArray *)componentsSeparatedByString:(NSString *)separator
                                   limit:(NSUInteger)limit;

@end

NSString+Split.m

#import "NSString+Split.h"

@implementation NSString (Split)

- (NSArray *)componentsSeparatedByString:(NSString *)separator
                                   limit:(NSUInteger)limit
{
    if (limit == 0) {
        return @[];
    }
    
    NSArray *components = [self componentsSeparatedByString:separator];
    if ([components count] > limit) {
        NSArray *a = [components subarrayWithRange:NSMakeRange(0, limit - 1)];
        NSArray *b = [components subarrayWithRange:NSMakeRange(limit - 1, [components count] - limit + 1)];
        components = [a arrayByAddingObject:[b componentsJoinedByString:separator]];
    }
    
    return components;
}

@end

NSStringSplitTest.m

#import <XCTest/XCTest.h>
#define HC_SHORTHAND
#import <OCHamcrestExtensions/OCHamcrest.h>
#import "NSString+Split.h"

@interface NSStringSplitTest : XCTestCase
{
}

@end

@implementation NSStringSplitTest

- (void)testComponentsReturnsAnArray
{
    assertThat([@"" componentsSeparatedByString:@"" limit:1],
               instanceOf([NSArray class]));
}

- (void)testStringCannotBeSplit
{
    assertThat([@"foo" componentsSeparatedByString:@"bar" limit:1],
               equalTo(@[@"foo"]));
}

- (void)testLimitIsZero
{
    assertThat([@"" componentsSeparatedByString:@"" limit:0],
               equalTo(@[]));
}

- (void)testSplittingAStringLessThanTheLimit
{
    assertThat([@"a-b-c" componentsSeparatedByString:@"-" limit:10],
               equalTo(@[@"a", @"b", @"c"]));
}

- (void)testLimitIsLessThanComponents
{
    assertThat([@"a-b-c-d" componentsSeparatedByString:@"-" limit:2],
               equalTo(@[@"a", @"b-c-d"]));
}

@end