Macro fruity__bbqsrc::ns_string

macro_rules! ns_string {
    ($s:expr) => { ... };
}

Creates an NSString from a static string.

Feature Flag

This macro is defined in foundation, which requires the foundation feature flag.

Examples

This macro takes a either a "string" literal or const string slice as the argument:

let hello = fruity::ns_string!("hello");
assert_eq!(hello.to_string(), "hello");

const WORLD: &str = "world";
let world = fruity::ns_string!(WORLD);
assert_eq!(world.to_string(), WORLD);

The result of this macro can even be used to create static values:

static WORLD: &NSString = fruity::ns_string!("world");

assert_eq!(WORLD.to_string(), "world");

Note that the result cannot be used in a const because it refers to static data outside of this library.

Unicode Strings

In Objective-C, non-ASCII strings are UTF-16. However, Rust strings are UTF-8.

This macro transcodes non-ASCII strings to UTF-16:

static HELLO_RU: &NSString = fruity::ns_string!("Привет");

assert_eq!(HELLO_RU.to_string(), "Привет");

Note that because this is implemented with const evaluation, massive strings can increase compile time and even hit the const evaluation limit.

Null-Terminated Strings

If the input string already ends with a 0 byte, then this macro does not append one.

let cstr = fruity::ns_string!("example\0");
let normal = fruity::ns_string!("example");

assert_eq!(cstr, normal);

Interior null bytes are allowed and are not stripped:

let example = fruity::ns_string!("exa\0mple");

Runtime Cost

None.

The result is equivalent to @"string" syntax in Objective-C.

Because of that, this should be preferred over NSString::from_str where possible.

Compile-time Cost

Minimal.

This is implemented entirely with const evaluation. It is not a procedural macro that requires dependencies for parsing.