Declared in NSArray+BlocksKit.h

Overview

Block extensions for NSArray.

Both inspired by and resembling Smalltalk syntax, these utilities allows for iteration of an array in a concise way that saves quite a bit of boilerplate code for filtering or finding objects or an object.

Includes code by the following:

Tasks

  • – bk_each:

    Loops through an array and executes the given block with each object.

  • – bk_apply:

    Enumerates through an array concurrently and executes the given block once for each object.

  • – bk_match:

    Loops through an array to find the object matching the block.

  • – bk_select:

    Loops through an array to find the objects matching the block.

  • – bk_reject:

    Loops through an array to find the objects not matching the block.

  • – bk_map:

    Call the block once for each object and create an array of the return values.

  • – bk_reduce:withBlock:

    Arbitrarily accumulate objects using a block.

  • – bk_reduceInteger:withBlock:

    Sometimes we just want to loop an objects list and reduce one property, where each result is a primitive type.

  • – bk_reduceFloat:withBlock:

    Sometimes we just want to loop an objects list and reduce one property, where each result is a primitive type.

  • – bk_any:

    Loops through an array to find whether any object matches the block.

  • – bk_none:

    Loops through an array to find whether no objects match the block.

  • – bk_all:

    Loops through an array to find whether all objects match the block.

  • – bk_corresponds:withBlock:

    Tests whether every element of this array relates to the corresponding element of another array according to match by block.

Instance Methods

bk_all:

- (BOOL)bk_all:(BOOL ( ^ ) ( id obj ))block
Discussion

Loops through an array to find whether all objects match the block.

Parameters

block

A single-argument, BOOL-returning code block.

Return Value

YES if the block returns YES for all objects in the array, NO otherwise.

Declared In

NSArray+BlocksKit.h

bk_any:

- (BOOL)bk_any:(BOOL ( ^ ) ( id obj ))block
Discussion

Loops through an array to find whether any object matches the block.

This method is similar to the Scala list exists. It is functionally identical to bk_match: but returns a BOOL instead. It is not recommended to use bk_any: as a check condition before executing bk_match:, since it would require two loops through the array.

For example, you can find if a string in an array starts with a certain letter:

 NSString *letter = @"A";
 BOOL containsLetter = [stringArray bk_any:^(id obj) {
   return [obj hasPrefix:@"A"];
 }];

Parameters

block

A single-argument, BOOL-returning code block.

Return Value

YES for the first time the block returns YES for an object, NO otherwise.

Declared In

NSArray+BlocksKit.h

bk_apply:

- (void)bk_apply:(void ( ^ ) ( id obj ))block
Discussion

Enumerates through an array concurrently and executes the given block once for each object.

Enumeration will occur on appropriate background queues. This will have a noticeable speed increase, especially on dual-core devices, but you must be aware of the thread safety of the objects you message from within the block. Be aware that the order of objects is not necessarily the order each block will be called in.

Parameters

block

A single-argument, void-returning code block.

Declared In

NSArray+BlocksKit.h

bk_corresponds:withBlock:

- (BOOL)bk_corresponds:(NSArray *)list withBlock:(BOOL ( ^ ) ( id obj1 , id obj2 ))block
Discussion

Tests whether every element of this array relates to the corresponding element of another array according to match by block.

For example, finding if a list of numbers corresponds to their sequenced string values; NSArray numbers = @[ @(1), @(2), @(3) ]; NSArray letters = @[ @“1”, @“2”, @“3” ]; BOOL doesCorrespond = [numbers bk_corresponds:letters withBlock:^(id number, id letter) { return [[number stringValue] isEqualToString:letter]; }];

Parameters

list

An array of objects to compare with.

block

A two-argument, BOOL-returning code block.

Return Value

Returns a BOOL, true if every element of array relates to corresponding element in another array.

Declared In

NSArray+BlocksKit.h

bk_each:

- (void)bk_each:(void ( ^ ) ( id obj ))block
Discussion

Loops through an array and executes the given block with each object.

Parameters

block

A single-argument, void-returning code block.

Declared In

NSArray+BlocksKit.h

bk_map:

- (NSArray *)bk_map:(id ( ^ ) ( id obj ))block
Discussion

Call the block once for each object and create an array of the return values.

This is sometimes referred to as a transform, mutating one of each object: NSArray *new = [stringArray bk_map:^id(id obj) { return [obj stringByAppendingString:@“.png”]); }];

Parameters

block

A single-argument, object-returning code block.

Return Value

Returns an array of the objects returned by the block.

Declared In

NSArray+BlocksKit.h

bk_match:

- (id)bk_match:(BOOL ( ^ ) ( id obj ))block
Discussion

Loops through an array to find the object matching the block.

bk_match: is functionally identical to bk_select:, but will stop and return on the first match.

Parameters

block

A single-argument, BOOL-returning code block.

Return Value

Returns the object, if found, or nil.

See Also

Declared In

NSArray+BlocksKit.h

bk_none:

- (BOOL)bk_none:(BOOL ( ^ ) ( id obj ))block
Discussion

Loops through an array to find whether no objects match the block.

This selector performs literally the exact same function as bk_all: but in reverse.

Parameters

block

A single-argument, BOOL-returning code block.

Return Value

YES if the block returns NO for all objects in the array, NO otherwise.

Declared In

NSArray+BlocksKit.h

bk_reduce:withBlock:

- (id)bk_reduce:(id)initial withBlock:(id ( ^ ) ( id sum , id obj ))block
Discussion

Arbitrarily accumulate objects using a block.

The concept of this selector is difficult to illustrate in words. The sum can be any NSObject, including (but not limited to) a string, number, or value.

For example, you can concentate the strings in an array: NSString *concentrated = [stringArray bk_reduce:@“” withBlock:^id(id sum, id obj) { return [sum stringByAppendingString:obj]; }];

You can also do something like summing the lengths of strings in an array: NSUInteger value = [[[stringArray bk_reduce:nil withBlock:^id(id sum, id obj) { return @([sum integerValue] + obj.length); }]] unsignedIntegerValue];

Parameters

initial

The value of the reduction at its start.

block

A block that takes the current sum and the next object to return the new sum.

Return Value

An accumulated value.

Declared In

NSArray+BlocksKit.h

bk_reduceFloat:withBlock:

- (CGFloat)bk_reduceFloat:(CGFloat)inital withBlock:(CGFloat ( ^ ) ( CGFloat result , id obj ))block
Discussion

Sometimes we just want to loop an objects list and reduce one property, where each result is a primitive type.

For instance, say we want to caculate the total balance from a list of people.

Code without using a block will be something like:

 NSArray *peoples = @[p1, p2, p3];
 CGFloat totalBalance = 0;
 for (People *people in peoples) {
     totalBalance += [people balance];
 }

We can use a block to make it simpler:

 NSArray *peoples = @[p1, p2, p3];
 CGFloat totalBalance = [peoples reduceFloat:.0f WithBlock:^CGFloat(CGFloat result, id obj, NSInteger index) {
     return result + [obj balance];
 }];

Declared In

NSArray+BlocksKit.h

bk_reduceInteger:withBlock:

- (NSInteger)bk_reduceInteger:(NSInteger)initial withBlock:(NSInteger ( ^ ) ( NSInteger result , id obj ))block
Discussion

Sometimes we just want to loop an objects list and reduce one property, where each result is a primitive type.

For example, say we want to calculate the total age of a list of people.

Code without using block will be something like:

 NSArray *peoples = @[p1, p2, p3];
 NSInteger totalAge = 0;
 for (People *people in peoples) {
     totalAge += [people age];
 }

We can use a block to make it simpler:

 NSArray *peoples = @[p1, p2, p3];
 NSInteger totalAge = [peoples reduceInteger:0 withBlock:^(NSInteger result, id obj, NSInteger index) {
     return result + [obj age];
 }];

Declared In

NSArray+BlocksKit.h

bk_reject:

- (NSArray *)bk_reject:(BOOL ( ^ ) ( id obj ))block
Discussion

Loops through an array to find the objects not matching the block.

This selector performs literally the exact same function as bk_select: but in reverse.

This is useful, as one may expect, for removing objects from an array. NSArray *new = [computers bk_reject:^BOOL(id obj) { return ([obj isUgly]); }];

Parameters

block

A single-argument, BOOL-returning code block.

Return Value

Returns an array of all objects not found.

Declared In

NSArray+BlocksKit.h

bk_select:

- (NSArray *)bk_select:(BOOL ( ^ ) ( id obj ))block
Discussion

Loops through an array to find the objects matching the block.

Parameters

block

A single-argument, BOOL-returning code block.

Return Value

Returns an array of the objects found.

See Also

Declared In

NSArray+BlocksKit.h