Convert String to StaticString

Question

Is there a way in Swift 3.0 to get a StaticString type out of a String type which is complex?

Example (needs a conversion to work):

let aString: StaticString = "One part" + "Second part"

let str: StaticString = "\(part1)\(part2)" is this what you need — Inder Kumar Rathore
– Inder Kumar Rathore, Commented Mar 23, 2017 at 10:47
@InderKumarRathore Actually the result is the same "Cannot convert value of one type to another" — Vanya
– Vanya, Commented Mar 23, 2017 at 10:51
I read the documentation and it says StaticString : A string type designed to represent text that is known at compile time. — Inder Kumar Rathore
– Inder Kumar Rathore, Commented Mar 23, 2017 at 10:56
Because of above constraint I don't think you can have dynamic text in it — Inder Kumar Rathore
– Inder Kumar Rathore, Commented Mar 23, 2017 at 10:57
The os_log API expects StaticString messages. It would be nice to be able to log dynamic messages. — Volker Mohr
– Volker Mohr, Commented Jun 19, 2018 at 12:24

Michael Dorner · Accepted Answer · 2017-03-23 13:13:24Z

14

This is not possible, because a StaticString is defined as

A simple string designed to represent text that is "knowable at compile-time". (Reference)

String concatenation happens at runtime.

I don't know what you are planing to do, but you can do something like that:

func aMethod(i: Int) -> StaticString {
    switch i {
    case 0:
        return "Simple"
    case 1:
        return "Complex"
    default:
        return "Default"
    }
}
let result = aMethod(i: 1)
print("\(type(of: result)): \(result)") // prints "StaticString: Complex"

edited Mar 23, 2017 at 13:13

answered Mar 23, 2017 at 11:06

Michael Dorner

20.6k16 gold badges95 silver badges132 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Vanya Over a year ago

Thank you Michael, but I am really interested in a generic hack way to do this sort of conversion.

vike Over a year ago

"String concatenation happens at runtime." was key to satisfy my search (w/ an upvote, though i'd love a reference for it ;).

Alfa · Accepted Answer · 2019-11-13 16:41:04Z

13

You can use format specifiers like %d or %s eg:

os_log("Successfully fetched %d recordings.", type: .info, count)
os_log("Getting recordings from %s.",
  type: .info, url.absoluteString)

for more info check here

answered Nov 13, 2019 at 16:41

Alfa

6297 silver badges22 bronze badges

Comments

superarts.org · Accepted Answer · 2020-04-22 18:52:51Z

5

Depends on your actual use case, you may have some way to work it around. For example, if you are dealing with os_log, you can use %@ if you want to use Swift String instead of CVarArg.

//os_log("Compiler error with: \(string).", log: log)
os_log("This is OK: %@.", log: log, string)

answered Apr 22, 2020 at 18:52

superarts.org

7,2881 gold badge62 silver badges45 bronze badges

Collectives™ on Stack Overflow

Convert String to StaticString

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related