Sentry Swift

[brustolin]

Introduction

A Sentry SDK started to be [written in Swift once,](https://github.com/getsentry/raven-swift) but due to ABI not being stable at that time, it got dropped. Since then Swift 5.1 landed and we got ABI stability. We’ve considered adding Swift to our sentry.cocoa SDK since then, but because of some of the trade offs, we’ve postponed that decision.

Motivation

This changed with our goal to better support SwiftUI. It’s growing in popularity and we need to write code in Swift in order to support it.

Considerations

• Swift is only available outside of an external dependency from iOS 13
  • This means, the app using out SDK, when targeting iOS 12 or older will require adding Swift as a dependency. But Swift is so popular that projects that support those iOS versions probably already contain swift.
• Since we support SPM and Carthage. We can’t add both Swift and Objective-C in the same Target.
  • For that reason, we need to add a second Target to sentry.cocoa. The idea is to create a Swift only new target that will be the main Sentry target, rename what we have today for SentryObjc, and make it a dependency of Sentry.
  • The problem with this approach is that we need to make public a few classes that used to be private, because we need to access it from the new Sentry target. This way, the user will also have access to this classes if they import the SentryObjc module in their projects.

[brustolin]

This PR shows how the project will look like.