Strings in Swift 4
Encountering a function that only accepts a
Substringwhen you want to pass aStringis less common — most functions should either take aStringor anyStringProtocol-conforming type. But if you do need to pass aString, the quickest way is to subscript the string with the range operator...without specifying any bounds[…][…]
You may be tempted to take full advantage of the existence of
StringProtocoland convert all your APIs to takeStringProtocolinstances rather than plainStrings. But the advice of the Swift team is not to do that[…][…]
Keep in mind, though, that as of Swift 4,
StringProtocolis not yet intended as a conformance target for your own custom string types. The documentation explicitly warns against it[…]
