Latest 0.1.1
Homepage https://github.com/rgerard/NSUnderscore
License MIT
Platforms ios 8.0, requires ARC
Authors

Introduction

NSUnderscore is a set of categories added to NSArray, NSDictionary, and NSSet. This project is an attempt to bring some of the useful functionality found in Underscore.js to the world of iOS programming. Not every single function has been ported over, as some functions are already implemented on the collection objects.

NSArray, NSDictionary and NSSet

Start by importing the appropriate category:

#import "NSUnderscore/NSArray+NSUnderscoreAdditions.h" or

#import "NSUnderscore/NSDictionary+NSUnderscoreAdditions.h" or

#import "NSUnderscore/NSSet+NSUnderscoreAdditions.h"

The following functions are available to you:

  • each

    • Iterates over a list of elements, yielding each in turn to an action function.
    • Example:
      NSArray *objects = @[@(2), @(4)];
      __block NSInteger total = 0;
      [objects each:^(NSNumber *object) {
      total += object.integerValue;
      }];
      // Result: total == 6
  • map

    • Produces a new array of values by mapping each value in list through a transformation function (action).
    • Example:
      NSArray *objects = @[@(2), @(3)];
      NSArray *modifiedObjects = [objects map:(id)^(NSNumber *object) {
      return @(object.integerValue * 2);
      }];
      // Result: modifiedObjects == @[ @(4), @(6) ]
  • reduce

    • Reduce boils down a list of values into a single value. Each successive step of it should be returned by action.
    • Example:
      NSArray *objects = @[@(2), @(4)];
      NSNumber *reduced = [objects reduce:(id)^(NSNumber *object, NSNumber *previousValue) {
      return @(object.integerValue + previousValue.integerValue);
      }];
      // Result: reduced == @(6)
  • filter

    • Looks through each value in the list, returning an array of all the values that pass a truth test
    • Example:
      NSArray *objects = @[@(2), @(4)];
      NSArray *filtered = [objects filter:(id)^(NSNumber *object) {
      return object.integerValue == 2;
      }];
      // Result: filtered == @[ @(2) ]
  • reject

    • Returns the values in list without the elements that the truth test (predicate) passes. The opposite of filter.
    • Example:
      NSArray *objects = @[@(2), @(4)];
      NSArray *filtered = [objects reject:(id)^(NSNumber *object) {
      return object.integerValue == 2;
      }];
      // Result: filtered == @[ @(5) ]
  • every

    • Returns true if all of the values in the list pass the predicate truth test.
    • Example:
      NSArray *objects = @[@(2), @(4)];
      BOOL result = [objects every:^BOOL(NSNumber *object) {
      return object.integerValue > 0;
      }];
      // Result: result == YES
  • some

    • Returns true if any of the values in the list pass the predicate truth test. Short-circuits and stops traversing the list if a true element is found.
    • Example:
      NSArray *objects = @[@(-2), @(4)];
      BOOL result = [objects some:^BOOL(NSNumber *object) {
      return object.integerValue < 0;
      }];
      // Result: result == YES
  • pluck

    • A convenient version of what is perhaps the most common use-case for map: extracting a list of property values.
    • Example:
      NSArray *objects = @[@{@"id": @(1)}, @{@"id": @(2)}];
      NSArray *plucked = [objects pluck:@"id"];
      // Result: plucked == [ @(1), @(2) ]
  • max

    • Returns the maximum value in list.
    • Example:
      NSArray *objects = @[@{@"id": @(10)}, @{@"id": @(20)}];
      NSDictionary *maxValue = [objects max:^NSInteger(NSDictionary *dict) {
      NSNumber *dictVal = (NSNumber *)[dict objectForKey:@"id"];
      return dictVal.integerValue;
      }];
      // Result: maxValue == @{@"id": @(20)}
  • min

    • Returns the minimum value in list.
    • Example:
      NSArray *objects = @[@{@"id": @(10)}, @{@"id": @(20)}];
      NSDictionary *minValue = [objects max:^NSInteger(NSDictionary *dict) {
      NSNumber *dictVal = (NSNumber *)[dict objectForKey:@"id"];
      return dictVal.integerValue;
      }];
      // Result: minValue == @{@"id": @(10)}
  • groupBy

    • Splits a collection into sets, grouped by the result of running each value through action.
    • Example:
      NSArray *testObjects = @[@{@"token": @"ryan-1"}, @{@"token": @"ryan-2"}, @{@"token": @"test-1"}];
      NSDictionary *groupedObjects = [testObjects groupBy:^id(NSDictionary *val) {
      NSString *token = [val objectForKey:@"token"];
      return [token substringToIndex:4];
      }];
      // Result: @{ @"ryan": [@{@"token": @"ryan-1"}, @{@"token": @"ryan-2"}], @"test": [@{@"token": @"test-1"}] }
  • indexBy

    • Given a list, and an action function that returns a key for each element in the list, returns an object with an index of each item.
    • Just like groupBy, but for when you know your keys are unique.
    • Example:
      NSArray *objects = @[@{@"token": @"1"}, @{@"token": @"2"}, @{@"token": @"3"}];
      NSDictionary *indexedObjects = [objects indexBy:^id(NSDictionary *val) {
      return [val objectForKey:@"token"];
      }];
      // Result: @{ @"1": @{@"token": @"1"}, @"2": @{@"token": @"ryan-2"}, @"3": @{@"token": @"3"}] }
  • countBy

    • Sorts a list into groups and returns a count for the number of objects in each group.
    • Similar to groupBy, but instead of returning a list of values, returns a count for the number of values in that group.
    • Example:
      NSArray *objects = @[@(1), @(2), @(3)];
      NSDictionary *countedObjects = [objects countBy:^id(NSNumber *val) {
      return val.integerValue % 2 == 0 ? @"even": @"odd";
      }];
      // Result: @{ @"even": 1, @"odd": 2 }
  • partition
    • Split array into two arrays: one whose elements all satisfy action and one whose elements all do not satisfy action.
    • Example:
      NSArray *objects = @[@(1), @(2), @(3)];
      NSDictionary *partitionedObjects = [objects partition:^BOOL(NSNumber *val) {
      return val.integerValue % 2 == 0;
      }];
      // Result: @[ @[ @(2) ], @[ @(1), @(3) ] ]

Latest podspec

{
    "name": "NSUnderscore",
    "version": "0.1.1",
    "summary": "NSUnderscore is a re-implementation of the key helper functions available in Underscore.js.",
    "description": "NSUnderscore is a set of categories added to NSArray, NSDictionary, and NSSet. This project is an attempt to bring some of the useful functionality found in Underscore.js to the world of iOS programming. Not every single function has been ported over, as some functions are already implemented on the collection objects.",
    "homepage": "https://github.com/rgerard/NSUnderscore",
    "license": "MIT",
    "authors": {
        "rgerard": "[email protected]"
    },
    "source": {
        "git": "https://github.com/rgerard/NSUnderscore.git",
        "tag": "0.1.1"
    },
    "social_media_url": "https://twitter.com/dreadpirateryan",
    "platforms": {
        "ios": "8.0"
    },
    "requires_arc": true,
    "source_files": "NSUnderscore/**/*"
}

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