The Xcode 11 and Swift Package Combo Platter

Since the Swift Package Manager (Swift PM or SPM) was introduced in late 2015 it has seemed like a natural fit for Xcode and SPM packages to work well together at some point in the future. At WWDC 2019, Apple announced that future was arriving in Xcode 11.

Icons for Xcode, a Swift Package Manager package, and an Xcode project

Xcode 11 provides two new ways to work with Swift Package Manager packages:

  • Open an SPM package in Xcode
  • Add SPM package dependencies to an Xcode project

These two new capabilities join a long-standing SPM feature:

  • Generate an Xcode project for an SPM package

Each of the these approaches are different both conceptually and in the nitty gritty details of what files they put where.

Open an SPM Package in Xcode

In Xcode 11, you can open a Swift Package Manager package directly in Xcode without needing a .xcodeproj Xcode project file.

Conceptually, you are working in a Swift Package Manager-centric world with the added ability of using Xcode to edit, build, and test your Swift package.

Note that this does not give you all of the settings and flexibility of an Xcode project. You cannot specify build phases, include resources, do code signing for an app, or any other functionality that is not currently supported by Swift Package Manager.

But being an Xcode project is not the purpose of this particular feature. This feature is all about using Xcode as an IDE for Swift PM packages.

What happens on disk?

Opening a package in Xcode adds a hidden .swiftpm/xcode directory to the package.

As you might guess, the xcode directory contains files Xcode uses such as a package.workspace file containing information about the workspace and xcuserdata and xcshareddata directories.

The .gitignore file generated when creating a new package includes xcuserdata as ignored. You will likely not want to add these files to your git repository. The files in xcshareddata on the other hand include shared schemes generated by Xcode which you may want to check into git to share among team members.


You will probably want to use the same policy of which Xcode-centric files to check in or ignore that you are using for Xcode projects.

The checked-out dependencies and build products are stored in the hidden .build directory, just like building the Swift package using swift build on the command line.

So, with a fairly small footprint of additional files, you can now use Xcode for Swift PM package development.

Add SPM Package Dependencies to an Xcode project

Also in Xcode 11, you can add Swift Package Manager packages as dependencies of an Xcode project.

Conceptually, you are working in an Xcode project-centric world with the added ability of having Xcode manage dependencies on Swift packages.

You specify the source URL and version of the package you want to use in your project. Xcode will automatically download the correct package version and any dependencies of that package. The dependencies are recorded in your Xcode project file, similar to dependencies on frameworks and libraries.

This is a significant addition. For the first time, Xcode has a native mechanism for managing and updating dependencies.

Developers in the Xcode ecosystem have traditionally turned to third-party solutions such as CocoaPods or Carthage for this functionality, or used git submodules in projects to combine code from different git repositories.

Xcode 11 opens the door to dependency-handling workflows that are actively supported by Apple and its tools.

But I don’t use Swift yet!

Even if your projects are not in Swift yet, you can create SPM packages with targets and products of C-based languages including Objective-C. The only Swift that must be in a package is the declarative Package.swift manifest file.

What happens on disk?

Adding SPM package dependencies to an Xcode project will add a Package.resolved file to the project’s workspace at xcshareddata/swiftpm. This file contains the resolved versions of each dependency. This file is intended to be included in source control so team members and continuous integration systems can use the same dependency versions.

As you might expect, the package dependencies will be referenced in the project’s project.pbxproj file.

There are no additional changes to the Xcode project and no hidden directories added. Everything else, including the downloaded package sources and build artifacts are located in the Xcode derived data directory for that project. The SourcePackages directory in the project’s derived data contains the checkouts and repositories for the Swift packages.

In addition to adding remote package dependencies to the project, Xcode will also recognize local package dependencies. This is useful, for example, if you are developing an app and a supporting package at the same time.

The addition of Swift package dependency management in Xcode gives you a powerful new option in structuring your projects’ dependencies.

Old Original SPM-Generated Xcode Project

Since the early days of the Swift Package Manager, you could generate an Xcode project for a package with the command swift package generate-xcodeproj.

This feature has always had limitations and drawbacks. With the new capability of opening a package directly in Xcode, you should never need to use this feature. But, it is still a temping option when looking at swift package help, so it might be helpful understanding why you don’t want to use this.

The SPM-generated Xcode project is intended as a convenience to use Xcode to view and edit your package. It is not meant to be a long-lasting resource.

If you make changes to the package’s manifest, add or remove dependencies, or make any significant changes, you need to regenerate the Xcode project. It is intended to be a transient resource, justconvenience to allow you to use Xcode to edit and build the package.

Because of this, the generated Xcode project was not intended to be shared or checked-in to source control. This is confirmed by looking in the .gitignore file automatically generated by SPM where /*.xcodeproj is on the list of files to be ignored.

The generated Xcode project stores some items within the xcodeproj directory including an Info.plist file per target in the package.

If your package has any C-based library targets, (for instance if you are exposing an existing C library to Swift), then the generated Xcode project contains a directory GeneratedModuleMap which contains a module map for each C-based target. The module map file contains a hard-coded path which includes the current user’s home directory. This makes the generated Xcode project decidedly un-shareable.

I am unable to think of a good use case for a generate Xcode project file now that Xcode 11 has the ability to open Swift packages directly. This functionality now seems obsolete.

Summary

With the introduction of Xcode 11, there are now three main ways to work with Swift Package Manager packages in Xcode:

Swift Package Manager-centric
Use Xcode as an IDE for Swift PM packages. No Xcode project required.

Xcode project-centric
Add Swift PM packages to an Xcode project. Xcode manages the dependencies.

Swift Package Manager generated Xcode project
Don’t use any more. Just open the package directly in Xcode 11.

The WWDC 2019 session Adopting Swift Packages in Xcode contains a number of demos showing how to use Xcode with Swift PM packages and is a good resource for getting started.

Xcode 11 makes great strides in working with Swift PM packages in two complimentary ways. •

A Kid in the June 2019 Candy Store

June 2019 has me feeling like a kid in a candy store.

I’m remarkably excited by the variety of things that are catching my interest and attention this month—so much so that I’m finding it difficult to decide what to do next.

A large part of that is due to all of the announcements at WWDC—but that is not all.

The Monday after WWDC, I wrote about an app I want to create that might be easier to build due to new technologies introduced at WWDC. Foremost among them was SwiftUI which I have really enjoyed digging into.

My week following the developer conference was a flurry of watching session videos and digging into things. But WWDC was not the only thing going on in the world in a few weeks back. On May 31st, Star Wars: Galaxy’s Edge opened at Disneyland.

Star Wars: Galaxy’s Edge

As a big Disneyland and Star Wars fan, had it been any other time of year, I would have tried to be there opening weekend. However, just days before WWDC, with a big LIVE near WWDC show to rehearse and prepare for, there was no way I could make it down to Anaheim.

I didn’t have to wait long though. Last weekend I had the chance to visit Galaxy’s Edge at Disneyland. I feel like they’ve done an amazing job of creating a place that feels very much a part of the Star Wars universe, even though it a brand new location not depicted in any of the movies. My inner nine-year old found it very satisfying to fly the Millennium Falcon, build my own lightsaber, and yes, drink some blue milk.

Combine Framework and Foundation

On Monday I headed home from Disneyland as Beta 2 dropped for Xcode 11, iOS 13, macOS 10.15, and all the rest.

The new beta includes Combine framework support for Foundation classes. So, it just became possible to write code to explore the same sort of data publishing pipelines that were presented in the Combine sessions at WWDC. This includes publishing notifications, properties, and timers.

So, another whole aisle of candy just opened up and I’ve spent most of the week catching up from my trip, rewatching Combine videos from WWDC, and playing around with Combine code.

So far, I am feeling the same sort of enjoyment in writing Combine code as I have had writing SwiftUI code. The main area of frustration I am finding with Combine is that the session videos are the primary place to see Combine sample code. (If I am missing a trove of Combine sample code from Apple – please let me know on Micro.blog or Twitter!) So, I’m finding that anything not covered in those sessions takes bit of trial and error to figure out.

Along the same lines, the code in the sessions often show the path from publisher through operators to subscriber, but don’t necessarily talk about who should be holding onto the publisher or the cancelable item returned from the subscriber, or exactly when it makes sense to set them up. It would be great to see more Combine framework sample code from Apple showing it in integrated into an app project, especially traditional UIKit and AppKit apps.

Toy Story 4, Forky, and WALT

Today I put the Combine framework aside for a few hours to go see Toy Story 4. Every time Pixar announces a sequel I worry that this is the one where they will jump the shark in the franchise. I am very happy to say that I really enjoyed Toy Story 4. I found Forky to be absolutely delightful!

If you know me for any length of time, you will soon discover that I am a big fan of Disney and Pixar animation.

WALT app icon
WALT app

The first iOS app I wrote is WALT: Watched Animation List Tracker. It’s not a commercial success by any means, but it’s an something I wanted to have in the world. It lists over 650 short and full length animated films from Disney Animation Studios and Pixar Animation Studios and lets you check off the ones you’ve watched.

Got to check off Toy Story 4 in WALT today.

I wrote about the creation of WALT shortly after I released it back in 2012. (Was that really about seven years ago? Wow!) A heads-up if you are thinking about paying 99 cents for the app, I do intend to make it a free app and add a tip jar. However there are many other things ahead of that on my to-do list, so I can’t tell you exactly when that will happen.

As mentioned in that original article, one inspiration for WALT was the The Walt Disney Family Museum (WDFM) in San Francisco. I have been a member since it opened ten years ago. The location is beautiful, in the Presidio with a view of the Golden Gate Bridge. And I find the museum and the story that it tells to be inspirational.

Fantasia Talk at The Walt Disney Family Museum

In addition to the exhibits at the museum, one of the things I enjoy most are the programs that they have throughout the year. In the past I have seen many great talks that speak to the creative process. For instance last year, I saw Brad Bird speak about his experiences working with classic Disney animators. I’ve seen animators Andreas Dejas and Floyd Norman talk about their time at Disney. And I’ve had the chance to see original Imagineers like Alice Davis and Marty Sklar.

Tomorrow I’ll heading up to San Francisco to see a talk by composer Fabrizio Mancinelli called The Beauty and Legacy of Fantasia. I’ve always enjoyed and been fascinated with the way animation and music can work together to achieve an effect and look forward to hearing what I believe will be an interesting perspective.

That’s A Lot Of Candy

In feeling like a kid in a candy store, June 2019 is not just some quaint little corner candy store. It’s been a giant store with aisle after aisle of classic candies, exotic candies from faraway places, and brand new candies you had never even heard of before.

With all of this intellectual and experiential candy, I hope I do not get the psychological equivalent of a bellyache. But even if I do, it has been a very memorable and enjoyable month so far. •

The Shortest Path To A Great App

The Shortest Path To A Great App” That is the phrase Apple used in a number of the SwiftUI sessions at WWDC last week. But beyond SwiftUI, there were a number of other announcements at WWDC 2019 that also could lead to a shorter path to a great app.

Taken in total, these announcements have left me feeling incredibly energized.

An Oddball WWDC Week

I have an oddball WWDC week compared to most people attending WWDC, AltConf, or Layers.

For the last eight years, I’ve organized and performed in the annual LIVE near WWDC concert on Wednesday night. The last four events have been benefit shows for App Camp For Girls.

I’ve also had the honor the past few years of closing out AltConf on Thursday afternoon with a lighthearted musical Week In Review session. Of course, I have no idea what I’ll be talking about until after Monday’s announcements.

Preparing for these events keeps me pretty busy until late Thursday afternoon—with a large chunk of Monday set aside for the Keynote and Platforms State of the Union—and then viewing sessions or snippets of sessions as I can.

So Friday is the first day of WWDC week I can dig deeper into everything that has been announced.

An Aha! Moment Before Breakfast

It dawned on me early Friday morning that a set of announcements at WWDC 2019 should make an app I have wanted to build much easier and quicker to create.

The annual LIVE near WWDC show is a complicated undertaking. This past year we had 24 performers playing 18 different instruments on 18 different songs.

In addition, for the past few years, Adam Tow has taken some really fantastic photos of the show.

So, for a long time I’ve wanted to build an app for my band, James Dempsey and the Breakpoints (JDBP). The app would be a place to share photos, lyrics and info with fans, and also be a resource for people performing in the show—the Breakpoints.

Fans would be able to download the free app and without an account, see photos, browse photos of past performances, see lyrics, maybe even play JDBP songs from Apple Music if they are subscribed.

Breakpoints would be able to sign in, see info about the upcoming show they are performing in, view the (ever changing) set list, know which songs they are playing on, and be able to swipe through the chord charts for the songs they are playing on, in order on an iPad (or iPhone in a pinch).

But, until last week, just thinking about building that app was exhausting. It would be just me writing it and would need a lot of infrastructure code to get it right.

Then, Friday morning, the thought occurred to me that these three newly announced technologies could make writing this app significantly faster and easier:

  • SwiftUI
  • Sign in with Apple
  • Core Data / CloudKit interoperability

A Journey of Discovery

Will these three newly announced technologies do the trick? What dead ends, limitations, and blind alleys will I discover?

At the moment I have no idea, and that’s exciting.

I still have videos to watch, documentation to read, and lots of code to write and fiddle around with.

The app I’m building won’t be open source, but I’m hoping to make it an ‘open process’ app. My plan is to write little blog posts as I go.

These posts will be me thinking out loud — expressing what I want this app to do before I’ve even fully investigated how I will implement it. And then reporting what I find as I investigate things and see how they work in practice. The intent is for this to be a public journal or technology travelogue as I go through the process of building an app.

I’m also hoping the posts will help spur discussion and feedback and help us all come to understand these technologies better.

Thanks Brent!

This approach was greatly inspired by Brent Simmons. I’ve always admired Brent’s ability to post in the casual and open manner of “Hey, I’m working on a thing. I’m learning it and I’m not an expert. Here’s what I’m discovering and here’s what is confusing to me.” Brent has been a prolific developer for many years, but he never claims to have all the answers. (Plus he plays a mean keyboard.)

A Last Caveat

This app is a side project. As the glow of WWDC 2019 fades and day to day tasks come back to the fore, there may stretches of time between posts about this app. I appreciate your patience in advance.

Let’s see how short that path really is.

I’m so excited to get started! •

Where I’ll be at WWDC 2019

I’ll be doing a few things next week at WWDC 2019 and wanted to pass along my schedule. Hope to see you at one or more of these happenings!

Tuesday: Micro.blog Meetup

Micro.blog Logo

Tuesday at lunch time, I’ll be at the Micro.blog meetup at the Grace Deli, across from The Hilton.

My good friend—and meetup organizer—Jean MacDonald and I co-host The Weekly Review, a ‘microcast’ podcast about personal productivity hosted on Micro.blog.

Stop by and say hello! We’ll also have The Weekly Review stickers to hand out. You can RSVP here.

Micro.blog Meetup, June 4th, 12 – 2 pm

Wednesday: LIVE near WWDC 2019

James Dempsey and the Breakpoints JDBP Logo
Wednesday night, my band, James Dempsey and the Breakpoints, performs our 8th annual LIVE near WWDC show. The party starts at 7 pm—tickets include an open bar. The band goes on at about 8:30 pm, playing a full concert of original, humorous, programming-oriented, and yes, even chart-topping music.

But the night is more than just music and fun—it’s a benefit concert for App Camp For Girls, with ticket proceeds going to support their mission. Come on out on Wednesday night to a great event for a great cause!

Tickets are still available but going fast. Click through to get all the details and buy tickets.

James Dempsey and the Breakpoints, LIVE near WWDC, presented by Capital One
Wednesday, June 5th, Doors open at 7:00 PM, show starts at 8:30 PM. Party until 11:00 PM

Thursday: AltConf WWDC 2019 Week In Review

AltConf Conference Logo
I’ll be closing out the week at AltConf with my sixth annual WWDC Week In Review, a lighthearted look back at the announcements and events of the week.

After a week front-loaded with announcements and technical talks—this easy-going closing session of AltConf combines humor, music, and perspective.

Join me for what usually proves to be an entertaining and occasionally enlightening session.

And, as usual, there will be a bit involving a ukulele.

AltConf 2019, June 3 – June 6, 2019
Closing Session, Thursday, June 6th, 3:00 PM

A Busy WWDC 2019 Week + Stickers!

As usual, it will be a busy WWDC week with plenty of new announcements and technology to wrap our heads around. If you see me out and about during the week, please say hello!

I’ll also have brand new James Dempsey and the Breakpoints and The Weekly Review stickers to hand out. Just ask for a sticker or two when you say hello!

I hope you can make it out to one or more of these events—see you at WWDC! •