IanKeen

public struct AnyCodable: Codable {
    public let value: Any?
    
    public init(_ value: Any?) {
        self.value = value
    }
    
    public init(from decoder: Decoder) throws {
        let container = try decoder.singleValueContainer()
        

IanKeen

extension Validator where Input == User, Output == User {
    static var validUser: Validator<User, User> {
        return .keyPath(\.name, .isNotNil && .isNotEmpty)
    }
}

struct User {
    let name: String?
}

timvermeulen

extension Sequence {
    func min(_ n: Int, by areInIncreasingOrder: (Element, Element) -> Bool) -> [Element] {
        var iterator = makeIterator()
        guard let first = iterator.next() else { return [] }
        
        return withoutActuallyEscaping(areInIncreasingOrder) { areInIncreasingOrder in
            var heap = NonEmptyMaxHeap(root: first, by: areInIncreasingOrder)
            var heapSize = 1
            
            while heapSize < n, let element = iterator.next() {

harlanhaskins

import Foundation

/// `StringScanner` is a fast scanner for Strings and String-like objects.
/// It's used to extract structured bits from unstructured strings, while
/// avoiding making extra copies of string bits until absolutely necessary.
/// You can build Scanners over Substrings, allowing you to scan
/// parts of strings and use smaller, more specialized scanners to extract bits
/// of that String without needing to reuse another scanner.
public struct StringScanner<Input: StringProtocol> {
  let input: Input

orta

tclementdev

libdispatch efficiency tips

The libdispatch is one of the most misused API due to the way it was presented to us when it was introduced and for many years after that, and due to the confusing documentation and API. This page is a compilation of important things to know if you're going to use this library. Many references are available at the end of this document pointing to comments from Apple's very own libdispatch maintainer (Pierre Habouzit).

My take-aways are:

• You should create very few, long-lived, well-defined queues. These queues should be seen as execution contexts in your program (gui, background work, ...) that benefit from executing in parallel. An important thing to note is that if these queues are all active at once, you will get as many threads running. In most apps, you probably do not need to create more than 3 or 4 queues.

• Go serial first, and as you find performance bottle necks, measure why, and if concurrency helps, apply with care, always validating under system pressure. Reuse

Qata

public extension Dictionary {
    /// Returns a dictionary where the keys are the first elements of
    /// the tuple and the values are the second elements, grouped in
    /// arrays associated with the given key.
    ///
    ///     let question = [(1, "Hello"), (2, "How"), (3, "Are"), (1, "You")]
    ///     let g = Dictionary(grouping: question)
    ///     // g == [1: ["Hello", "You"], 2: ["How"], 3: ["Are"]]
    ///
    /// - Returns: A dictionary containing the grouped elements of this sequence.

khanlou

let zipped = zip([1,2,3], default: 0, ["a"], default: "-")

print(Array(zipped))

let zippedSameType = zip([1,2,3], [1], default: 0)

print(Array(zippedSameType))

smileyborg

// UICollectionView Objective-C example

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
        
    NSIndexPath *selectedIndexPath = [[self.collectionView indexPathsForSelectedItems] firstObject];
    if (selectedIndexPath != nil) {
        id<UIViewControllerTransitionCoordinator> coordinator = self.transitionCoordinator;
        if (coordinator != nil) {
            [coordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext> context) {

anandabits

// This example shows how higher-kinded types can be emulated in Swift today.
// It acheives correct typing at the cost of some boilerplate, manual lifting and an existential representation.
// The technique below was directly inspired by the paper Lightweight Higher-Kinded Polymorphism
// by Jeremy Yallop and Leo White found at http://ocamllabs.io/higher/lightweight-higher-kinded-polymorphism.pdf

/// `ConstructorTag` represents a type constructor.
/// `Argument` represents an argument to the type constructor.
struct Apply<ConstructorTag, Argument> {
    /// An existential containing a value of `Constructor<Argument>`
    /// Where `Constructor` is the type constructor represented by `ConstructorTag`