iOS ClassDecl panic - Should I do something before a ClassDecl?

[Nazariglez]

Hey hi!

I'm trying to do something simple, just declaring my AppDelegate like this lib.rs:

use objc::declare::ClassDecl;
use objc::runtime::{BOOL, Object, Sel, YES, NO};

type Obj = *mut Object;

extern "C" fn did_finish_launching_with_options(_: &mut Object, _: Sel, _: Obj, _: Obj) -> BOOL {
    println!("DID FINISH LAUNCHING");
    YES
}

pub fn start() {
    println!("START - HELLO FROM LIB?");


    let ui_responder_cls = class!(UIResponder);
    let mut app_delegate_cls = ClassDecl::new("AppDelegate", ui_responder_cls)
        .expect("Failed to declare AppDelegate");

    unsafe {
        app_delegate_cls.add_method(
            sel!(application:didFinishLaunchingWithOptions:),
            did_finish_launching_with_options as extern "C" fn(&mut Object, Sel, Obj, Obj) -> BOOL,
        );

        app_delegate_cls.register();
    }
}

#[no_mangle]
pub extern "C" fn start_app() {
    start();
}

And it's used on xcode as this main.m:

#import "ffi.h"

int main(int argc, char * argv[]) {
        start_app();
        return 0;
}

But always got a panic when I do the expect, is an Option so I don't have an error to read and to know what was wrong. I checked the examples, and reduced the examples to the minimum, using NSObject and extending it instead of using UIResponder, and it's the same result.

Am I missing something? (Testing on simulator).

Thanks!

[madsmtm]

The class name has to be unique, there probably exists a class named AppDelegate somewhere already. Try MyAppDelegate, MyAppDelegate1, MyRustAppDelegate or similar names.

[Nazariglez]

This is it. My fault. I was trying to reproduce the same code that I had on my xcode project from rust. Does make sense to change the option for an error telling the user that the name should be unique?

I may be dumb, however, I think that some extra info will be nice.

Thanks!

[madsmtm]

Does make sense to change the option for an error telling the user that the name should be unique?

Probably would be a good idea, or at the very least document duplicate names as a common error case.