DevAndArtist

func ?? <T>(_ optional: T?, _ trap: @autoclosure () -> Never) -> T {
	switch optional {
	case .some(let value):
		return value
	case .none:
		trap()
	}
}

DevAndArtist

import Darwin
import UIKit

protocol _LoggerDelegate : AnyObject {
	///
	func logger(_ logger: Logger, received newString: String)
}

final class Logger {
	///

DevAndArtist

import UIKit

protocol ViewComponent : AnyObject {
  ///
  func isAncestor(of descendant: Self) -> Bool

  ///
  func isDescendant(of ancestor: Self) -> Bool

DevAndArtist

import RxSwift

public final class DisposeCache<Key>
  : ExpressibleByDictionaryLiteral where Key : Hashable {
  ///
  private var lock = NSRecursiveLock()

  ///
  private var storage: [Key: Disposable]

DevAndArtist

protocol ValueContainer {
  associatedtype Value
  var value: Value { get }
  init(_ value: Value)
}

extension ValueContainer where Self : Equatable, Value : Equatable {
  static func == (lhs: Self, rhs: Self) -> Bool {
    return lhs.value == rhs.value
  }

DevAndArtist

class Ref {
  weak var obj: Obj? {
    didSet { print("didSet", obj as Any) }
  }
}

class Obj {
  weak var ref: Ref?

  func unlink(from ref: Ref) {

DevAndArtist

public struct Unique<Key, Value>: Hashable where Key: Hashable {

  public enum KeyVariant {
    case key(Key)
    case keyPath(KeyPath<Value, Key>)
    case closure((Value) -> Key)

    internal func _key(for value: Value) -> Key {
      switch self {
      case .key(let key):

DevAndArtist

Application Development Techniques

Drivable UI

@dynamicMemberLookup
struct DriverFor<Base> {
 var base: Base

DevAndArtist

Property Delegates

The original proposal: https://github.com/DougGregor/swift-evolution/blob/property-delegates/proposals/NNNN-property-delegates.md

---

What is proposed?

• A user can create custom property delegates that allow a var declaration to decide how to implement the storage.
• The original proposal want to use a new identifier space, prefixed by $, to uniquely identify a property delegate from the computed and non-prefixed main property.

DevAndArtist

WWDC 2019 Labs Questions

Size changes propagation to child view controller

In A Look Inside Presentation Controllers - WWDC 2014 session the following pattern was introduced.

• A child view controller or a presented view controller can issue a request for size update by setting its preferredContentSize property.
• A parent view controller or a presentation controller will receive a callback on preferredContentSizeDidChangeForChildContentContainer method.
• At this point the receiver can decide if can allow the size request and layout the child view controller or the presented view controller.