Golang, CGO, double pointers and macos Foundation framework - c

Question

First, I have some basic C experience, but not too fluent with CGO and macos programming
I write a function, that removes a file in a system Trash. I have a working code, that I try to improve
The code first:
package trash
/*
#cgo CFLAGS: -x objective-c
#cgo LDFLAGS: -framework Foundation
#import "trash.h"
*/
import "C"
import (
"errors"
"unsafe"
)
// TrashItem puts items into system trash
func TrashItem(filePath string) error {
cString := C.CString(filePath)
defer C.free(unsafe.Pointer(cString))
var cErr = new(C.Error)
res := C.TrashItem(cString, cErr)
if res == 0 {
// convert cErr to go error
return errors.New("...")
}
return nil
}
#import <Foundation/Foundation.h>
typedef struct _Error {
long C;
const char *E;
} Error;
const BOOL TrashItem(const char *filePath, Error *error);
(I googled a lot to write this code, not sure, how good it is)
#import "trash.h"
const BOOL TrashItem(const char *filePath, Error *error) {
NSFileManager *manager = [NSFileManager defaultManager];
NSURL *fileURL = [[NSURL alloc] initFileURLWithPath:#(filePath)];
NSError *e;
BOOL success = [manager trashItemAtURL:fileURL resultingItemURL:nil error:&e];
if (!success) {
error->C = e.code;
error->E = [e.localizedDescription UTF8String];
}
return success;
}
First issue:
I don't wont to always initialize var cErr = new(C.Error). I think I could make trash function accept Error **error, but I struggle to pass double pointer from go to C (I have go pointer have go pointer error)
Second issue:
I would like to avoid custom Error struct and pass NSError * and access fields from go side.
I had Incompatible pointer types passing 'struct NSError *' to parameter of type 'NSError *, but https://stackoverflow.com/a/60715306/889530 solved it for me
But I think I still need NSError **, so I can read the data back, and again I struggle with void and double pointers here.
Can somebody explain me how to do that properly