Including Swift Bundle Supervisor Help – Half 2

Within the earlier publish I checked out a few of the historical past of how we packaged up our library code to be used by our fellow builders. We checked out a few 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 have been vital 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 realized 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 sources are wanted and in addition normal construct settings just like the vary and varieties of supported platforms. Extra exactly, these settings are contained within the undertaking.pbxproj file inside your xcodeproj bundle.

With SwiftPM there isn’t any such undertaking file. Slightly every part is outlined in human-readable kind within the Bundle.swift file.

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

Bundle Definition

Step one, and most essential one, is so as to add a package deal definition file to the foundation 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 may encounter, together with a dependency on one other package deal, a few sources 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: "Take a look at",
            exclude: ["Info.plist"],
            sources: [.copy("Resources/receipt"),
                        .copy("Resources/sandboxReceipt")]),
    ]
)

The primary line may solely appear like a remark to you, however it will be important for the swift instruments to find out what syntax components are supported. Model 5.3 is required when you have sources in any goal. Should you set that to one thing decrease you get syntax errors concerning the useful resource definitions. Should you set that to five.3 however don’t specify useful resource definitions (for non-standard sources) you’ll get warnings about unknown recordsdata that you must both exclude or outline as sources.

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 check goal has sources. I may get extra inexperienced checkmarks on Swift Bundle Index if I eliminated the .testTarget definition.

On the opposite facet the swift instruments allow you to run thusly outlined unit exams from the command line and functioning unit exams additionally ought to rely as an indication of excellent library high quality. Lastly, all people must be utilizing Swift 5.3 anyway as that’s the baseline commonplace for the reason that launch of Xcode 12.

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

The fundamental setup of the package deal definition is easy. You’ve the package deal identify, then some minimal platform variations. Notice that these minimal OS variations don’t imply that that would prohibit 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 kind: .dynamic you get a dynamic framework as a substitute. The targets array specifies which targets will get merged into the ultimate product.

I assumed for a second that that is likely to be good to have the sources be added to the framework as a substitute of a separate useful resource bundle, like we’re used to. However alas the dealing with of sources stays the identical and so they 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 must 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 method 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 now have a daily goal for the package deal and a check goal for all of the unit exams. Should you don’t specify a path then SwiftPM expects the supply code within the Sources folder beneath the goal’s folder and sources in a Assets folder. I’ve a special 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 undertaking. And for the check goal I specify two sources to be copied with the trail relative to the goal customized path. These copy directions are vital as a result of the contained sources don’t have a kind that Xcode is aware of easy methods to deal with. For issues like strings recordsdata or XIBs you don’t need to 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 check goal requires the principle goal to work. That’s additionally a distinction to Xcode the place the examined code resides inside a number utility, the place’s right here it’s compiled into the unit check bundle.

Goal Issues

You is likely to be questioning why there’s a distinction between merchandise and targets in SPM. One motive for that you’ve got already seen: there isn’t any motive for the check 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 may assume that Swift Bundle Supervisor would solely all you to have code written in Swift. However you’d be unsuitable, Any language goes, additionally Goal-C and different C dialects. However SPM doesn’t can help you combine C-based languages with Swift in a single goal.

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

The opposite good motive for a separate goal and product was to have some frequent information mannequin code that may be utilized by inside targets and in addition 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 may additionally make use of these definitions internally.

Every product turns into its personal module.

Resourcefulness

I discussed above that you would be able to let SPM do its personal factor in relation to commonplace useful resource varieties, like localised strings, XIBs, storyboards and asset catalogs. Should you use string localisation although, you must specify the undertaking’s default language.

Different varieties you must both particularly exclude or specify what must be finished for it. You possibly can both specify a .copy for every particular person useful resource or additionally for all the Assets folder. Since I’ve solely two check recordsdata and that’s not going to vary, it wasn’t an excessive amount of work so as to add these individually.

SPM expects sources 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 undertaking file the place you may 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 web site like POEditor however you need them to be included in numerous targets. A method 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/Assets/*.lproj
rm -rf ../TFMExtension/Assets/*.lproj

PWD=`pwd`

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

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

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

finished

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

Platform-specific Code

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

For instance, every part that references UIKit can’t be compiled for macOS or watchOS, so I’ve a number of locations in DTCoreText or DTFoundation (each written in Goal-C) the place all the 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 clarification as to why, however including the import for the header fastened it.

Contained in the Xcode Venture

The adjustments for conditional compilation apart, there may be nothing it’s worthwhile to change in your Xcode undertaking – until you wish to. The principal setup for the package deal occurs in Bundle.swift. You possibly can 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 undertaking 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 undertaking navigator pane, Xcode will add an area package deal reference for you, with an emblem of a cute little field.

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

This additionally creates a scheme for constructing the package deal and the package deal’s merchandise develop into out there to hyperlink/embed to your app. Bundle merchandise have an icon of a greek temple. If they’re static libraries then they are going to 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 check goal. This fails as a result of unit exams require XCTest which doesn’t excite for watchOS.

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

Library Unit Checks

To run the unit exams contained within the check goal, all it’s worthwhile to do is to run swift check on the command line, from the repository root folder.

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

The accessor works by figuring out the trail of the executable and setting up a bundle identify from names of package deal and goal. Within the case of unit exams 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 practical, workaround for that is as follows:

func urlForTestResource(identify: String, ofType ext: String?) -> URL?
{
	let bundle = Bundle(for: kind(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 a substitute of the check bundle
	// that aborts unit exams with message:
	//   Deadly error: couldn't load useful resource bundle: /Functions/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 check 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 begin 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.

Probably the most annoying limitation remaining is that you just can’t 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 parts additionally make it engaging for library distributors to think about supporting Swift Bundle Supervisor. Having the dependency administration taken care of by Xcode is the best function of all.

Additionally revealed on Medium.

Classes: Administrative