Including Swift Bundle Supervisor Help – Half 2

Within the earlier publish I checked out a number of the historical past of how we packaged up our library code to be used by our fellow builders. We checked out a number of the advantages of static libraries versus dynamic frameworks which additionally include headers wanted by the integrator.

Now let’s dive into the steps that had been crucial for me to allow SPM help on the primary few libraries DTCoreText, DTFoundation and Kvitto. It took me a number of days to iron out all of the kinks and I’d like to share with you what I discovered within the course of.

We’re used to utilizing Xcode to explain what goes right into a construct: Which recordsdata to compile, what exterior libraries to hyperlink to, what assets are wanted and likewise basic construct settings just like the vary and varieties of supported platforms. Extra exactly, these settings are contained within the mission.pbxproj file inside your xcodeproj bundle.

With SwiftPM there isn’t any such mission file. Somewhat the whole lot is outlined in human-readable type within the Bundle.swift file.

For some primary terminology: we outline sure merchandise (i.e. static library, dynamic framework, app bundle and so forth, useful resource bundle, unit take a look at bundle), that relate to numerous targets (a bucket for a bunch of supply code recordsdata and assets). Here’s a distinction from Xcode the place goal and product is used synonymously.

Bundle Definition

Step one, and most necessary one, is so as to add a package deal definition file to the basis folder of the repository. It must be on this place as a result of Swift Packages are referenced by the repository URL and SwiftPM will solely have a look at the highest folder for Bundle.swift.

Right here’s the definition for Kvitto, for reference. This has all components you would possibly encounter, together with a dependency on one other package deal, a few assets on high of the definition of 1 product and a number of goal.

// swift-tools-version:5.3

import PackageDescription

let package deal = Bundle(
    identify: "Kvitto",
    platforms: [
        .iOS(.v9),         //.v8 - .v13
        .macOS(.v10_10),    //.v10_10 - .v10_15
        .tvOS(.v9),        //.v9 - .v13
    ],
    merchandise: [
        .library(
            name: "Kvitto",
            targets: ["Kvitto"]),
    ],
    dependencies: [
        .package(url: "https://github.com/Cocoanetics/DTFoundation.git", 
		from: "1.7.15"),
    ],
    targets: [
        .target(
            name: "Kvitto",
            dependencies: [
                .product(name: "DTFoundation", 
				package: "DTFoundation"),
            ],
            path: "Core",
            exclude: ["Info.plist"]),
        .testTarget(
            identify: "KvittoTests",
            dependencies: ["Kvitto"],
            path: "Check",
            exclude: ["Info.plist"],
            assets: [.copy("Resources/receipt"),
                        .copy("Resources/sandboxReceipt")]),
    ]
)

The primary line would possibly solely appear to be a remark to you, however it is necessary for the swift instruments to find out what syntax components are supported. Model 5.3 is required in case you have assets in any goal. Should you set that to one thing decrease you get syntax errors relating to the useful resource definitions. Should you set that to five.3 however don’t specify useful resource definitions (for non-standard assets) you’re going to get warnings about unknown recordsdata that it’s best to both exclude or outline as assets.

I discovered myself conflicted about that, as I had talked about within the earlier article. All code would work on Swift 5.0 and up and solely the take a look at goal has assets. I might get extra inexperienced checkmarks on Swift Bundle Index if I eliminated the .testTarget definition.

On the opposite aspect the swift instruments allow you to run thusly outlined unit assessments from the command line and functioning unit assessments additionally ought to depend as an indication of fine library high quality. Lastly, everyone ought to be utilizing Swift 5.3 anyway as that’s the baseline customary because the launch of Xcode 12.

That’s why I selected to depart it at that.

The fundamental setup of the package deal definition is simple. You’ve gotten the package deal identify, then some minimal platform variations. Be aware that these minimal OS variations don’t imply that that might limit the the package deal to particular platforms.

The merchandise part defines what sort of library comes out of the construct course of. The default setting (invisible) is to provide a static library, by specifying sort: .dynamic you get a dynamic framework as an alternative. The targets array specifies which targets will get merged into the ultimate product.

I assumed for a second that that could be good to have the assets be added to the framework as an alternative of a separate useful resource bundle, like we’re used to. However alas the dealing with of assets stays the identical they usually get bundled right into a Product_Target.bundle. So due to this fact I’d somewhat have the static library – which is able to get merged into the app binary – somewhat than having yet one more separate framework bundle contained in the app bundle.

As I defined within the earlier article, dynamic frameworks ought to be prevented if the supply code for libraries is public. So we’re proud of the static library default.

The dependencies part lists the exterior reference to different packages. You specify the repository URL and the minimal variations. The proven means with from and a model would settle for all 1.x.x variations from and together with 1.7.15. There are additionally different methods to specify a precise quantity or sure ranges.

Final come the targets. We’ve a daily goal for the package deal and a take a look at goal for all of the unit assessments. Should you don’t specify a path then SwiftPM expects the supply code within the Sources folder beneath the goal’s folder and assets in a Sources folder. I’ve a distinct construction, so I specified a customized path.

I’ve to exclude the Data.plist for each targets as a result of that is utilized by two targets outlined contained in the Xcode mission. And for the take a look at goal I specify two assets to be copied with the trail relative to the goal customized path. These copy directions are crucial as a result of the contained assets don’t have a kind that Xcode is aware of the right way to deal with. For issues like strings recordsdata or XIBs you don’t should specify something.

Evaluate the dependencies key of each targets. On the one hand you see that I’m referencing the exterior dependency of the principle goal. Then again the take a look at goal requires the principle goal to work. That’s additionally a distinction to Xcode the place the examined code resides inside a bunch software, the place’s right here it’s compiled into the unit take a look at bundle.

Goal Issues

You could be questioning why there’s a distinction between merchandise and targets in SPM. One motive for that you’ve already seen: there isn’t any motive for the take a look at goal to be represented in a product. Easy packages will usually solely have one product which may solely consist of 1 goal.

Though I already discovered two extra causes, to separate code out into extra particular person targets after which additionally merchandise.

You would possibly assume that Swift Bundle Supervisor would solely all you to have code written in Swift. However you’ll be unsuitable, Any language goes, additionally Goal-C and different C dialects. However SPM doesn’t permit you to combine C-based languages with Swift in a single goal.

In a single mission I had some Goal-C code for a perform with loads of ifs. I rewrote that in Swift solely to seek out that compiling this could take greater than a minute, in contrast to a couple seconds in Goal-C. So I selected to depart the perform because it was. The answer was to place it right into a separate Goal-C goal and refer that to an inner dependency from the principle Swift goal.

The opposite good motive for a separate goal and product was to have some frequent knowledge mannequin code that might be utilized by inner targets and likewise by way of import in an app consuming my library. In locations the place the consumer would solely want the shared definitions he would import the particular module for that. Elsewhere he would import different targets which in flip might additionally make use of these definitions internally.

Every product turns into its personal module.

Resourcefulness

I discussed above you could let SPM do its personal factor on the subject of customary useful resource varieties, like localised strings, XIBs, storyboards and asset catalogs. Should you use string localisation although, you need to specify the mission’s default language.

Different varieties you need to both particularly exclude or specify what ought to be achieved for it. You’ll be able to both specify a .copy for every particular person useful resource or additionally for your entire Sources folder. Since I’ve solely two take a look at recordsdata and that’s not going to vary, it wasn’t an excessive amount of work so as to add these individually.

SPM expects assets in the identical folder {that a} goal’s supply recordsdata reside in (or a sub-folder thereof). The explanation for that’s once more that there isn’t any Xcode mission file the place you might specify membership of sure recordsdata to particular targets. You specify what belongs the place by how it’s specified by the file system together of the package deal definition.

Say you’ve got a single place the place you’ve got localised strings recordsdata downloaded from a translation website like POEditor however you need them to be included in numerous targets. A way to attain that’s to create soft-links contained in the goal’s useful resource folders to the recordsdata. I wrote this shell script to create the lproj folders for all languages after which create the hyperlinks.

#!/bin/sh

echo "Eradicating current strings"
rm -rf ../TFMViews/Sources/*.lproj
rm -rf ../TFMExtension/Sources/*.lproj

PWD=`pwd`

for entry in *.lproj
do
  echo "Linking $entry..."

  mkdir ../TFMViews/Sources/$entry
  ln -s ../../../Strings/$entry/TFMViews.stringsdict 
     ../TFMViews/Sources/$entry
  ln -s ../../../Strings/$entry/TFMViews.strings 
     ../TFMViews/Sources/$entry

  mkdir ../TFMExtension/Sources/$entry
  ln -s ../../../Strings/$entry/TFMExtension.stringsdict 
     ../TFMExtension/Sources/$entry
  ln -s ../../../Strings/$entry/TFMExtension.strings 
     ../TFMExtension/Sources/$entry

achieved

The identical strategy of soft-links will also be employed for Goal-C based mostly packages the place you may hyperlink to all related public headers in an embrace folder.

Platform-specific Code

Because the package deal has no facility for limiting particular supply code to particular platforms or OS variations, you’ll face the state of affairs that sure code received’t compile for different platforms. A workaround for this limitation is using conditional compilation directives.

For instance, the whole lot that references UIKit can’t be compiled for macOS or watchOS, so I’ve a couple of locations in DTCoreText or DTFoundation (each written in Goal-C) the place your entire implementation is enclosed in:

#import <TargetConditionals.h>

#if TARGET_OS_IPHONE && !TARGET_OS_WATCH
...
#endif

I additionally discovered that generally I needed to additionally import the TargetConditionals header for the defines to work. Particularly sure Goal-C class extensions in DTCoreText wouldn’t be seen within the public interface if I didn’t import this header. I’ve no rationalization as to why, however including the import for the header fastened it.

Contained in the Xcode Undertaking

The adjustments for conditional compilation apart, there may be nothing it’s essential change in your Xcode mission – until you need to. The principal setup for the package deal occurs in Bundle.swift. You’ll be able to construct the package deal with issuing swift construct.

I discovered it handy so as to add a reference to the package deal contained in the Xcode mission as a result of this lets you debug your code within the context of being compiled for a package deal. Should you drag any folder (containing a package deal definition) into the mission navigator pane, Xcode will add a neighborhood package deal reference for you, with an emblem of a cute little field.

In Xcode 12 there’s a bug that in the event you try this for the mission folder itself, it appears to work, however when you shut the mission and reopen it once more, the reference turns into defunct. The best way to repair it’s to vary the reference to “Relative to Undertaking” and open the folder selector by way of the folder button and re-select the mission root folder.

This additionally creates a scheme for constructing the package deal and the package deal’s merchandise develop into obtainable to hyperlink/embed to your app. Bundle merchandise have an icon of a greek temple. If they’re static libraries then they may get merged into the app binary, dynamic frameworks shall be added to the app’s Frameworks folder.

Xcode additionally creates a scheme for the package deal, inserting it in .swiftpm/xcode/xcshareddata/xcschemes/. I moved it into the shared schemes folder of the xcodeproj and renamed it to Kvitto-Bundle.xcscheme.

I had the watchOS platform builds on Swift Bundle Index fail as a result of xcodebuild insists on constructing all targets, together with the take a look at goal. This fails as a result of unit assessments require XCTest which doesn’t excite for watchOS.

By offering an aptly named shared scheme it can solely construct the principle goal and I achieved inexperienced checkmarks for watchOS on SPI.

Library Unit Exams

To run the unit assessments contained within the take a look at goal, all it’s essential do is to run swift take a look at on the command line, from the repository root folder.

Some magic was required to get that to work as a result of take a look at recordsdata required by the unit assessments usually are not bundled within the .xctest bundle. For normal packages a useful resource bundle accessor is being routinely generated, which you need to use with Bundle.module.

The accessor works by figuring out the trail of the executable and developing a bundle identify from names of package deal and goal. Within the case of unit assessments the executable is xcrun contained within the Xcode.app bundle the place it has no probability of discovering the Kvitto_KittoTests.bundle.

My ugly, however useful, workaround for that is as follows:

func urlForTestResource(identify: String, ofType ext: String?) -> URL?
{
	let bundle = Bundle(for: sort(of: self))
		
	#if SWIFT_PACKAGE
		
	// there's a bug the place Bundle.module factors to the trail of xcrun contained in the Xcode.app bundle, as an alternative of the take a look at bundle
	// that aborts unit assessments with message:
	//   Deadly error: couldn't load useful resource bundle: /Purposes/Xcode.app/Contents/Developer/usr/bin/Kvitto_KvittoTests.bundle: file KvittoTests/resource_bundle_accessor.swift, line 7
		
	// workaround: attempt to discover the useful resource bundle on the construct path
	let buildPathURL = bundle.bundleURL.deletingLastPathComponent()
		
	guard let resourceBundle = Bundle(url: buildPathURL.appendingPathComponent("Kvitto_KvittoTests.bundle")),
	   let path = resourceBundle.path(forResource: identify, ofType: ext) else
	{
		return nil
	}
		
	return URL(fileURLWithPath: path)
		
	#else
		
	guard let path = bundle.path(forResource: identify, ofType: ext) else
	{
		return nil
	}
		
	return URL(fileURLWithPath: path)
		
	#endif
}

This depends on the truth that the useful resource bundle shall be created parallel to the xctest bundle, in the identical construct folder. The #if SWIFT_PACKAGE conditional compilation will solely be added if this code is constructed as a part of a swift package deal. With this workaround, the earlier mechanisms of working the unit take a look at scheme by way of Xcode continues to work.

The wonderful thing about Swift being open supply, is that we will additionally examine the code for the useful resource accessor on GitHub. It seems that the talked about bug has already been addressed there. The repair was made too late to make it into Swift 5.3 in Xcode 12 however has been confirmed to be current in Xcode 12.2.

Conclusion

I discover that the evolution of Swift Bundle Supervisor as progressed sufficiently to start out including help for it to my libraries. It’s doable and advisable to take action along with different methods of integration, like Xcode subproject, Cocoapods or Carthage.

Essentially the most annoying limitation remaining is that you just can not restrict targets to sure platforms or specify a variety of supported OS variations per goal. However these can simply be labored round with conditional compilation directives.

The standard standards partially enforced by the Swift Bundle Index coupled with the discoverability of elements additionally make it enticing for library distributors to think about supporting Swift Bundle Supervisor. Having the dependency administration taken care of by Xcode is the best characteristic of all.

Additionally revealed on Medium.

Classes: Administrative