Code coverage for Swift Packages with Fastlane

Package.swift file in Swift packages describes the package contents including other dependencies, build targets and so on. Double-clicking a Package.swift file opens Xcode with that package and one can build and run tests. When adding continues integration to a Swift package then we would like to build, test, and also create a code coverage report. …

Custom string interpolation in Swift

ExpressibleByStringInterpolation is a protocol which makes it possible to compose strings with expressions evaluated at runtime. Interpolated strings are created with adding a \(some code) to a string. Those expressions are evaluated and a final string is created. This protocol, among other things, enables customizing strings what are created by those expressions. At the end …

Reading Fastfiles with document based SwiftUI app on macOS

WWDC'20 brought an addition to SwiftUI apps which enables to create document based applications in SwiftUI. Along with DocumentGroup API two new protocols were added: FileDocument and ReferenceFileDocument. The first one is meant for value types and the latter one for class type document types. For seeing how much effort it takes to create a …

Adding prefixMap for expensive operations in Swift

Swift Foundation contains a lot of useful functions on collection types. In the context of this blog post we are interested in map(_:) and prefix(while:). Map is used for transforming collection elements and prefix(while:) for getting a sequence containing initial elements until the predicate is true. In some cases the predicate used in the prefix(while:) …

Measurement, Unit, Dimension, and MeasurementFormatter on iOS

I was looking at formatters provided by Foundation framework and this time I would like to put some attention on MeasurementFormatter. Like the name says, it is used for creating localized strings of some sort of measurements. Measurements are represented by a generic struct Measurement where the generic UnitType describes the unit represented by it. …