In Swift, how do you overwrite a file only if it hasn't changed?

asked 2015-07-08 12:29:28 -0500

In Swift, I am trying to overwrite a file only if it hasn't changed, but I get this error when I give an Etag to "if-none-match":

400 Bad Request If-None-Match only supports *

Is there a way to check-and-write?

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