replace forEach with for in

[tomholub]

I'd like to ban .forEach in this codebase. Let's instead usefor thing in things {, in this case for newKeyToAdd in newKeysToAdd {. I'll make another issue, to do this across the codebase.

Originally posted by @tomholub in #1165 (comment)

[tomholub]

[tomholub]

It's for consistency with our other codebases, on other platforms.

Also to ensure there is always "one obvious way to do a thing". When you have an array and you want to iterate over it and return, then it's .map and friends. If you want to iterate without returning, then it's for x of y. It makes the intention clear. No need for yet-another-way to do a loop with forEach.

[tomholub]

The more the code looks like code on our other platforms, the easier is to do code reviews - which I have to do in 3 different languages. This was one of the reasons we embraced async/await here even though it meant dropping support for iOS < 15.

[tomholub]

Your second version is good. You can (though don't have to) still shorten it as follows:

for realmKey in keys.compactMap { try? PubKeyRealmObject($0) } {
    self.pubKeys.append(realmKey)
}

[tomholub]

Absolutely