in src/platform_impl/macos/view.rs [596:611]
fn get_characters(event: id, ignore_modifiers: bool) -> String {
unsafe {
let characters: id = if ignore_modifiers {
msg_send![event, charactersIgnoringModifiers]
} else {
msg_send![event, characters]
};
assert_ne!(characters, nil);
let slice =
slice::from_raw_parts(characters.UTF8String() as *const c_uchar, characters.len());
let string = str::from_utf8_unchecked(slice);
string.to_owned()
}
}