iOS notes

Swift

Herald's concepts are the same on every platform. Where Swift differs, the API follows Swift:

• Calls don't wait or throw. track, set, identify and the rest return once every vendor has the call: no await, no try. Vendor SDKs do their own work in the background, so a call takes very little time. A provider of your own must return quickly too, and do slow work, such as a network request, in a Task.
• Vendors report failures instead of throwing them. A vendor that can't send a call passes the error to Herald.reportFailure, and Herald sends it to your error reporter with the vendor's name and the call.
• Setup mistakes stop the app. A provider without a name or capabilities, two providers with the same name, or a fallback factory that isn't last, stop the app at start-up with a message saying what to change.
• Your own factory that stores a vendor object, such as an Amplitude or a MixpanelInstance, needs @preconcurrency import of that vendor's module in Swift 6, because vendor SDKs aren't marked Sendable. Xcode offers the fix.
• HeraldCore.Identity. Amplitude has an Identity type too, so in a file that imports both, write the module name in front.

Failures

• Each failure reaches the error reporter as soon as its vendor reports it, on the thread that made the call, not after every vendor has finished.
• Your own provider must return quickly, because Herald calls each provider on your thread and waits for it. See Custom providers.