Swift Libraries and Designated Requirements
The problem I’m running into now, as I dabble with adding Swift-based code to MarsEdit, is the bundled Swift libraries are being signed with my app’s custom designated requirement.
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The copying of Swift libraries and their subsequent signing is not only opaque to developers, but it happens after the entire user-configurable build process is done.
The custom designated requirement causes the libraries to be reported as “modified or invalid.” The workaround is to re-sign your app from a shell script, after Xcode has finished building it. I have been doing this for a long time, for other reasons, and recommend it.