Month: July 2018

Two Creational Design Patterns in Swift 4: Factory Method and Singleton

My original article — “Design Patterns in Swift #1: Factory Method and Singleton” — was published on appcoda.com.

There are 23 classic software development design patterns probably first identified, collected, and explained all in one place by the “Gang of Four” (“GoF”), Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides in their seminal book, “Design Patterns: Elements of Reusable Object-Oriented Software.” This tutorial focuses on two of those patterns in terms of what the GoF calls the “creational” category: “factory method” and “singleton.” Follow along with the Xcode projects both on GitHub, available for factory method here and singleton here.

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Finding memory leaks with the Xcode Memory Graph Debugger and fixing leaks with unowned and weak

In this tutorial, I’ll show you how to track down memory leaks within Xcode via the Memory Graph Debugger, new since Xcode 8. This is a powerful visual tool and doesn’t require you to step out of Xcode and start the Leaks Instrument. Once we identify some memory leaks, I’ll show you how to plug those leaks by using the Swift language’s weak and unowned qualifiers, and talk about the differences between the two qualifiers.

I recently discussed iOS memory management and memory leaks that occur when using reference semantics and reference types (classes) in my tutorials on “Swift 4 memory management via ARC for reference types (classes)” and “Fixing memory leaks — strong reference cycles — in Swift 4.” After reading these articles, you should understand how easy it is to inadvertently encode and introduce a strong reference cycle into your Swift 4 code and thus end up with a memory leak. You should also understand how generally straightforward it is to fix such a memory leak. My sample code in both tutorials was didactic. What about real-world projects with hundreds of thousands or millions of lines of code? Suppose that you’ve heard reports of diminished app performance, low memory warnings, or just plain app crashes. Finding memory leaks in your code is quite cumbersome when trying to debug via rote inspection, setting breakpoints, adding logging statements, etc.

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Fixing memory leaks — strong reference cycles — in Swift 4

PREREQUISITES FOR THIS TUTORIAL

If you don’t understand how Swift manages memory for classes (reference types), you need to read the first article in this series, “Swift 4 memory management via ARC for reference types (classes)”. Once you understand how reference type-based memory is managed with ARC, you’ll be ready to understand how to prevent memory leaks from occurring in your app. Remember that ARC only applies to reference (class) types, not value types like struct and enum instances.

THE ARC DEALLOCATION PROCESS

Remember how we visualized the reference count that ARC maintains on the allocated instance of reference type Widget in my introductory ARC tutorial?

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New in iOS 12 – Adding a Custom UI and Interactivity Inside Local and Push Notifications

My original article – “New in iOS 12: Adding a Custom UI and Interactivity in Local and Push Notifications” – was published on appcoda.com.

INTRODUCTION

If you look at Apple’s “What’s New in iOS” 12 page, you’ll find a section entitled “Interactive Controls in Notifications,” which exclaims:

Notification content app extensions now support user interactivity in custom views. If the content of your app’s notifications needs to prompt user interaction, add controls like buttons and switches.

In this tutorial, I’m going to show you how to give your local and remote (push) notifications a custom user interface (UI). Users can now interact with a notification’s content area. iOS 12 has given us the ability to add a UIViewController subclass to notifications which we can customize. We can add controls like UIButton, UIImageView, and UISwitch to the view controller, wire up custom functionality using IBOutlet and IBAction, and arrange our custom UI using Auto Layout — all within the notification itself. We can provide support for more than a single tap. We can develop pretty much any type of user experience we want, within notification space limitations and timing considerations.

I’ll show you how a user can take action in response to a notification by interacting only with a customized notification interface, and conveniently not having to open up an app. I’ll be showcasing software released to developers just ten days ago (June 19), specifically iOS 12 beta 2 and Xcode 10 beta 2.

By the end of this tutorial, you’ll be able allow to your app users to get a notification, see a custom UI, click on a button, and get a confirmation — all inside a notification, like so:

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New in iOS 12 – Implementing Provisional Authorization for Quiet Notifications in Swift 4.2

RELATED: Learn how to add a custom user interface INSIDE OF local and push notifications in “New in iOS 12 — Adding a Custom UI and Interactivity Inside Local and Push Notifications.”

With iOS 12, Apple fine-tuned the notification authorization process and expanded notification delivery options, giving developers the ability to build apps with high opt-in, reaction, and retention rates, thus leading to potentially higher revenues. The company announced these new features during a WWDC 2018 presentation entitled “What’s New in User Notifications.” App developers now have the ability to start sending notifications without explicit permission, i.e., on a trial basis. Apple calls this new notification management protocol “provisional authorization” which is closely related to a feature they’ve named “deliver quietly.” In this tutorial, I’ll show you how to encode these new notification features using software released to developers just fifteen days ago (June 19), specifically iOS 12 beta 2 and Xcode 10 beta 2 (which includes Swift 4.2).

To give you an idea of the code I’ll be writing and explaining in this tutorial, here are two videos of my sample app delivering a notification provisionally on an iPhone 8 Plus. Notice iOS 12 has multiple options for configuring how future notifications will be delivered:

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