How to convert items of NSArray to utf16 (char16_t)? - nsarray

Question

I have a function that gets all contents of directory whether files or directories and I am using contentsOfDirectoryAtPath to collect the content of a directory then I save the names of files/directories into a container called contentsStore which accepts key&value items of UTF-16 string char16_t. look at the following code to make your vision clear:
NSArray *dirContents = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:_dirPath error:nil];
for(unsigned int i= 0; i< [dirContents count]; i++){
if(isDir){
// `contentsStore` is key&value container that accepts utf-16 string (char16_t)
contentsStore.Add([[dirContents objectAtIndex:i] UTF8String], "directory");
} else {
contentsStore.Add([[dirContents objectAtIndex:i] UTF8String], "file");
}
}
Note that I don't post the entire code because it's big but I just added the important parts that related to the problem. Also, I am using Objective-C just as a bridge to achieve my goal to use Cocoa in macOS but the main language that I use is C++, so, the entire code is a combination of C++/Objective-C.
How to make the objectAtIndex method to output the item's content as UTF-16 char16_t?

Answer 1

the following will give you an idea. The [Filemanager defaultmanager] is actually supporting your task. You can convert the path to C-string and convert then into string of char16_t aka basic_string<char16_t>.
NSString *_dirPath = [[NSBundle mainBundle] bundlePath];
NSError *error = nil;
NSFileManager *manager = [[NSFileManager defaultManager] init];
NSArray *dirContents = [manager contentsOfDirectoryAtPath:_dirPath error:&error];
if (!error && dirContents.count ) {
for(unsigned int i = 0; i < [dirContents count]; i++){
NSString *path = [dirContents objectAtIndex:i];
BOOL isDir;
std::string usingkey = "file";
if ([manager fileExistsAtPath:path isDirectory:&isDir] && isDir) {
usingkey = "directory";
}
const char *fileRepresentation = [manager fileSystemRepresentationWithPath:path];
// function declared below..
std::u16string char16string = to_utf16(fileRepresentation);
// and use it to store your C++ storageObject, value&key pair
// don't know of what datatype is usingkey in your source
// just assumed std::string
contentsStore.Add(char16string, usingkey);
}
}
you will have to include the following in your .mm implementation
#include <string>
#include <codecvt>
#include <iostream>
#implementation Yourclassname
//std::u16string is same as basic_string<char16_t>
std::u16string to_utf16( std::string str )
{ return std::wstring_convert< std::codecvt_utf8_utf16<char16_t>, char16_t >{}.from_bytes(str); }
#end