Avoid a "variable was written to, but never read" without unnecessary read statements

Using Swift
2

Normally, you can just do _ = c, but there's also a problem that you need to ensure that c is still alive by the completion event.

If you're not reading from c, the compiler can assume that c isn't being used, and optimize it out. That'd be bad since you're retaining c to maintain the publisher subscription.

Use withExtendedLifetime on the last access to ensure that c is still alive by then. That last access should be in the completion block.

Could be either:

c = withExtendedLifetime(c) { nil }

// or

withExtendedLifetime(c) {}
c = nil
6 Likes