staltz

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

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This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

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emotality

NOTE (2022-07-09): Xcode finally added this functionality in Xcode 14, please see release notes here:

New Features in Xcode 14 Beta 3
When editing code, the Edit > Duplicate menu item and its corresponding keyboard shortcut now duplicate the selected text — or the line that currently contains the insertion point, if no text is selected. (8614499) (FB5618491)

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Xcode line duplicate

Bind keys to duplicate lines in Xcode

IanKeen

class Lazy<T> {
    private(set) var  created: Bool = false
    private(set) lazy var value: T = {
        created = true
        return builder()
    }()
    
    private var builder: () -> T
    
    init(_ builder: @escaping () -> T) {

IanKeen

import UIKit

class BufferView<Child: UIView>: UIView {
    override var layoutMargins: UIEdgeInsets {
        didSet { configure() }
    }
    override var isHidden: Bool {
        didSet { configure() }
    }

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

vinczebalazs

import UIKit

extension UIView {
    
    var allSubviews: [UIView] {
        subviews + subviews.flatMap { $0.allSubviews }
    }
    
    func firstSubview<T: UIView>(of type: T.Type) -> T? {
        allSubviews.first { $0 is T } as? T