How do I convert NSString to an encoding other than UTF-8?

Question

I'm working with c in iOS Project I'm trying to convert my string to respected type in c , below code is supposed to send to core Library

typedef uint16_t    UniCharT;
static const UniCharT s_learnWord[] = {'H', 'e','l','\0'};

what i have done till now is string is the one what I'm passing

NSString * string = @"Hel";
static const UniCharT *a = (UniCharT *)[string UTF8String];

But it is failing to convert when more than one character , If i pass one character then working fine please let me where i miss, How can i pass like s_learnWord ?

and i tried in google and StackOverFLow none of the duplicates or answers didn't worked for me like this Convert NSString into char array I'm already doing same way only.

Possible duplicate of [Convert NSString into char array](https://stackoverflow.com/questions/3581532/convert-nsstring-into-char-array) — roy, Oct 21 '19 at 12:43
i don't think so roy , i'm doing same conversion any way i updated my question, Thank you — Praveen Kumar, Oct 21 '19 at 12:54
and one morething is i have to pass `const UniCharT* insertString;` this is declared in library so i have to pass to `insertString` — Praveen Kumar, Oct 21 '19 at 13:13
`uint16_t s_learnWord[] = {'H', 'e','l','\0'};` also shouldn't work. — Cy-4AH, Oct 21 '19 at 13:22

pmdj · Accepted Answer · 2019-10-21T13:22:07.960

1

Your question is a little ambiguous as the title says "c type char[]" but your code uses typedef uint16_t UniCharT; which is contradictory.

For any string conversions other than UTF-8, you normally want to use the method getCString:maxLength:encoding:.

As you are using uint16_t, you probably are trying to use UTF-16? You'll want to pass NSUTF16StringEncoding as the encoding constant in that case. (Or possibly NSUTF16BigEndianStringEncoding/NSUTF16LittleEndianStringEncoding)

Something like this should work:

include <stdlib.h>

// ...

NSString * string = @"part";
NSUInteger stringBytes = [string maximumLengthOfBytesUsingEncoding];
stringBytes += sizeof(UniCharT); // make space for \0 termination
UniCharT* convertedString = calloc(1, stringBytes);
[string getCString:(char*)convertedString
         maxLength:stringBytes
          encoding:NSUTF16StringEncoding];

// now use convertedString, pass it to library etc.

free(convertedString);

edited Oct 21 '19 at 13:22

answered Oct 21 '19 at 13:12

pmdj

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Or `cStringUsingEncoding:` – Cy-4AH Oct 21 '19 at 13:13
1

@Cy-4AH [The documentation for `cStringUsingEncoding:`](https://developer.apple.com/documentation/foundation/nsstring/1408489-cstringusingencoding?language=objc) states "**Special Considerations** UTF-16 and UTF-32 are not considered to be C string encodings, and should not be used with this method—the results of passing NSUTF16StringEncoding, NSUTF32StringEncoding, or any of their variants are undefined." So no, don't use `cStringUsingEncoding:` here. – pmdj Oct 21 '19 at 13:14
i mean okay `static const UniCharT s_learnWord[] = {'H', 'e','l','\0'};` if i pass this it is working fine, can you please suggest me how to convert like `s_learnWord` from `NSString` – Praveen Kumar Oct 21 '19 at 13:16
@PraveenKumar I've given an example that should help you get started. – pmdj Oct 21 '19 at 13:22
@pmdj Thanks man you are right i need to convert `UTF16String`, working fine now – Praveen Kumar Oct 22 '19 at 06:37

How do I convert NSString to an encoding other than UTF-8?

1 Answers1