Paul Hudson September 23rd 2019 @twostraws

• Swift Playground Mac Os
• Swift Playgrounds For Mac Os

Availability checking in Swift gives us the ability to ask whether the user is running a specific or newer version of an operating system, and run code only if that test passes. This allows us to use the latest functionality from iOS, macOS and so on, while also degrading gracefully for users on older iOS versions.

How it used to be: manual version checking

Without Swift's availability checking, you would have to check for version compatibility by hand. For example, if you want to use UICollectionViewCompositionalLayout in your app but wanted to support users on iOS 12 and earlier, you'd need to do a run-time operating system version number check and use that new layout only if it were supported. For example:

AppDelegate.swift and ViewController.swift. We will add more code to ViewController.swift in a while. There is also: The Main.storyboard file to design the app’s user interface graphically. The Assets catalog where any images or other assets that should be included in the app bundle must be added to. Availability checking in Swift gives us the ability to ask whether the user is running a specific or newer version of an operating system, and run code only if that test passes. This allows us to use the latest functionality from iOS, macOS and so on, while also degrading gracefully for users on older iOS versions.

This approach was fraught with problems, not least trying to remember when each component was introduced. Worse, what if you missed some code? If your app tried to use iOS 13 code on iOS 12, or iOS 12 code on iOS 11, it would just crash, which meant developers who were keen use the latest and greatest APIs had to spend a lot of time adding checks to their code, and ensuring it was crash-free.

1. Building Objective-C or Swift apps for macOS.; 5 minutes to read; In this article. To start building your first Mac app, you'll need to do these steps: Connect to your repository service account (GitHub, Bitbucket, VSTS, Azure DevOps). Select a repository and a branch where your app lives.
2. #swift #swiftui #mac So far, nearly all the articles I have seen about SwiftUI show it being used for iOS, more particularly for iPhone. But SwiftUI works on all Apple’s platforms, and as I am primarily a Mac developer, I decided to try out a Mac app and see what happened.
3. The Swift version isn't going to be the main issue in supporting older versions of macOS. All Swift versions up to version 5.0 support macOS 10.9 and later. The main issue in supporting older versions of macOS is going to be Apple's frameworks. Examples: Storyboards require 10.10 and later.

Swift's solution: Automatic operating system API availability checking

Way back in Swift 2, Apple introduced API availability checking. If you set your app's Deployment Target to a lower iOS release than the base SDK, Xcode will automatically scan every API you use to make sure it's available in your lowest deployment target version. This information has been in Apple's API headers for years, but it's only now being exposed to the compiler. What it means is that if your app compiles, you can be guaranteed it doesn't call any code that can't run because of missing APIs.

By default, you don't need to do anything: Swift will compare your actual usage against your minimum deployment target, and if it finds any unavailable API then you'll get an error – and that's when the work begins.

Returning to our example, if you have used UICollectionViewCompositionalLayout and your deployment target is set to iOS 12.0, you'll get a compile error because stack views aren't available before 13.0. The solution is to tell Xcode you want certain code to execute only on iOS 13.0 or later, like this:

In that code, #available is going to check whether we're on iOS 13 or later, or any other unknown platforms that might get announced in the future – that's the * at the end, and it's required. And that's it: all the code you'll put in place of '// use UICollectionViewCompositionalLayout' effectively has elevated rights to use iOS 13.0-only technology, whether that's classes, methods or enums.

If code inside a method should only be run on certain iOS versions, you can also use #available with guard to produce code like this:

The power of #available is that the compiler can now check and enforce API usage on older operating systems, which previously was entirely human – it's a huge improvement, and one I know will catch on quickly.

Marking whole methods and classes with @available

As you just saw, you can use if #available to run version-specific code in small blocks. But what if whole methods are off limits? Or perhaps even whole classes? Swift has these scenarios covered too, using the @available attribute.

@available works similarly to #available in that you specify the iOS release you want to target, and then Xcode handles the rest. For example:

If your deployment target is iOS 12, you can't call that useCompositionalLayout() method without some availability checking first. You can stack up these checks if you need to, for example:

Each time, there's effectively a privilege elevation so you can use version-limited APIs.

Swift Playground Mac Os

For the ultimate in restrictions, you can also mark whole classes as being available only in a specific iOS release or later – just move the @available code wherever you want it.

There is one last neat feature about these availability checks in Swift: you no longer need to worry about 'Required' and 'Optional' frameworks – the compiler sorts all that out for you now. Hurray for developer productivity!

About the author

Paul Hudson is the creator of Hacking with Swift, the most comprehensive series of Swift books in the world. He's also the editor of Swift Developer News, the maintainer of the Swift Knowledge Base, and a speaker at Swift events around the world. If you're curious you can learn more here.

To fly online with VATSIM, you will need to download and install a software application which connects your Flight Simulator with the VATSIM servers. There are several such applications, and all are free. Clients are available for P3D, X-Plane, Microsoft Flight Simulator (2020), FSX and FS9 across several operating systems. These applications also enable you to communicate with ATC and other aircraft. To do this, a headset with microphone is very useful, but not required. Text communication is always available. There is extensive information and help for all pilot clients in the VATSIM Forums.

There are a great many other users, both pilots and ATC, logged on to the VATSIM network at any given time. Before you fly online, you are expected to first become familiar with the various aspects of VATSIM such as:

Currently all Pilot clients are written for Windows except XSquawkbox which is only used for X-Plane and can be used in Windows, Mac OS and Linux.

Which pilot client should I use?

Please note that all pilot clients work in Windows. Swift and xSquawkbox also work in Mac OS and Linux.

Audio for VATSIM Compatibility

In-built - Audio for VATSIM is already built into the client and you need only set up your microphone and speakers/headset and your client connects to Audio for VATSIM.

Standalone Client Required - Audio for VATSIM has not yet been integrated into the client so the standalone Audio for VATSIM client is required. Connect to VATSIM first through your preferred pilot client and then connect to the standalone Audio for VATSIM client.

vPilot - (P3D, Microsoft Flight Simulator 2020 and FSX)

vPilot is a simple, effective client designed to get new pilots flying quickly with excellent model matching so that you can see other online pilots with the correct aircraft type and livery. Generally, it's 5-10 minutes from download to working, including setting up your model matching. Documentation is thorough. vPilot is supported by not only the community but by the developer who continues to make feature improvements, and is the most commonly used pilot client on VATSIM.
vPilot is probably the best choice for new members that use P3D, Microsoft Flight Simulator 2020 and FSX because it is quick and easy to install and get started with.

xPilot - (X-Plane only)

xPilot is the newest pilot client built especially for X-Plane but with the ever familiar look and feel of vPilot (for P3D and FSX).

xPilot is probably the best choice for new members that use X-Plane because it is quick and easy to install and get started with.

Swift Playgrounds For Mac Os

Swift - (P3D, X-Plane, FSX, FS9)

Swift is a new pilot client for VATSIM currently undergoing open beta testing. It is compatible with all the main pilot clients and several operating systems. It is a feature-rich client but the instructions must be read

xSquawkbox - (X-Plane only)

xSquawkbox is a well established pilot client for connecting to X-Plane and can run on Windows, Mac OS and Linux. The download includes installation instructions.

There is a very useful FAQ here.

Some definitions of terms used above:

FSX - Microsoft Flight Simulator X
FS9 - Microsoft Flight Simulator (also known as FS2004)
FS2002 - Microsoft Flight Simulator 2002
P3D - Prepar3D (pronounced “prepared”) a visual simulation platform that allows users to create training scenarios
Model Matching - refers to the process by which the pilot software selects which 3D model and texture to display while connected to VATSIM