Converting NSData to NSString in Objective c

Question

I want to convert NSData to NSString..What is the best way to do this?

I am using this code but the final string returns null

NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"%@",str);

When I see console It will print null.

@Nik.... @Marvin: Are you the same person or from within the same lan? I just wonder, why your [identicons](http://stackoverflow.com/questions/392280/what-is-the-algorithm-used-to-generate-those-little-gravatar-identicon-images/392288#392288) are exactly the same. — vikingosegundo, Jun 20 '11 at 13:49
What's the string? If you're getting `nil` then I guess your data isn't a valid utf8 string? — deanWombourne, Jun 20 '11 at 13:49
@vikingosegundo For your kind information i don't know nik... — Mehul Mistri, Jun 21 '11 at 04:04
that is really funny, as it is extremely unlikely. but still possible. — vikingosegundo, Jun 21 '11 at 07:19

Jhaliya - Praveen Sharma · Answer 1 · 2011-06-20T13:41:57.620

100

Use below code.

NSString* myString;
myString = [[NSString alloc] initWithData:nsdata encoding:NSASCIIStringEncoding];

edited Jun 20 '11 at 13:41

answered Jun 20 '11 at 13:35

Jhaliya - Praveen Sharma

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9

this will not give me the proper string – Mehul Mistri Jun 20 '11 at 13:37
3

if not, it is not `NSASCIIStringEncoding`. see [felipes answer](http://stackoverflow.com/questions/6411965/converting-nsdata-to-nsstring-in-objective-c/6412275#6412275) for other encodings – vikingosegundo Jun 20 '11 at 20:10
For this encoding NSUTF8StringEncoding giving nil – Muhammad Shauket Sep 16 '20 at 06:43

score 48 · Accepted Answer · edited Jul 02 '17 at 03:10

The docs for NSString says

https://developer.apple.com/documentation/foundation/nsstring/1416374-initwithdata

Return Value An NSString object initialized by converting the bytes in data into Unicode characters using encoding. The returned object may be different from the original receiver. Returns nil if the initialization fails for some reason (for example if data does not represent valid data for encoding).

You should try other encoding to check if it solves your problem

 // The following constants are provided by NSString as possible string encodings.
enum {
   NSASCIIStringEncoding = 1,
   NSNEXTSTEPStringEncoding = 2,
   NSJapaneseEUCStringEncoding = 3,
   NSUTF8StringEncoding = 4,
   NSISOLatin1StringEncoding = 5,
   NSSymbolStringEncoding = 6,
   NSNonLossyASCIIStringEncoding = 7,
   NSShiftJISStringEncoding = 8,
   NSISOLatin2StringEncoding = 9,
   NSUnicodeStringEncoding = 10,
   NSWindowsCP1251StringEncoding = 11,
   NSWindowsCP1252StringEncoding = 12,
   NSWindowsCP1253StringEncoding = 13,
   NSWindowsCP1254StringEncoding = 14,
   NSWindowsCP1250StringEncoding = 15,
   NSISO2022JPStringEncoding = 21,
   NSMacOSRomanStringEncoding = 30,
   NSUTF16StringEncoding = NSUnicodeStringEncoding,
   NSUTF16BigEndianStringEncoding = 0x90000100,
   NSUTF16LittleEndianStringEncoding = 0x94000100,
   NSUTF32StringEncoding = 0x8c000100,
   NSUTF32BigEndianStringEncoding = 0x98000100,
   NSUTF32LittleEndianStringEncoding = 0x9c000100,
   NSProprietaryStringEncoding = 65536
};

I used the numbers in lldb. Otherwise it didn't work. Thanks. — Okhan Okbay, Feb 06 '18 at 06:24
Note: If you are unsure of your encoding type or if it isn't always the same, this approach will be good for you: https://stackoverflow.com/a/50691430/2057171 — Albert Renshaw, Jun 05 '18 at 03:11

score 17 · Answer 3 · answered Jun 20 '11 at 13:40

17

-[NSString initWithData:encoding] will return nil if the specified encoding doesn't match the data's encoding.

Make sure your data is encoded in UTF-8 (or change NSUTF8StringEncoding to whatever encoding that's appropriate for the data).

answered Jun 20 '11 at 13:40

Morten Fast

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I converted an image into the NSdata and again converting the NSdata into the String using the NSUTF8StringEncoding. But it is showing nil. – Ramakrishna Oct 08 '16 at 06:06

Alexander Volkov · Answer 4 · 2019-08-27T10:35:23.360

6

Objective C:

[[NSString alloc] initWithData:nsdata encoding:NSASCIIStringEncoding];

Swift:

let str = String(data: data, encoding: .ascii)

edited Aug 27 '19 at 10:35

answered Mar 27 '16 at 13:41

Alexander Volkov

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score 5 · Answer 5 · answered May 26 '14 at 05:44

5

NSString *string = [NSString stringWithUTF8String:[Data bytes]];

answered May 26 '14 at 05:44

Nag Raj

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This does not work as described [[NSString alloc] initWithData:head encoding:NSUTF8StringEncoding] works – Ryan Heitner Jan 07 '15 at 11:34

score 2 · Answer 6 · edited May 16 '13 at 11:04

2

-[NSString initWithData:encoding] is your friend but only when you use a proper encoding.

edited May 16 '13 at 11:04

DD_

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answered Jan 17 '13 at 07:01

Bilal Khan

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score 1 · Answer 7 · answered Aug 01 '17 at 11:50

1

Swift:

let jsonString = String(data: jsonData, encoding: .ascii)

or .utf8 or whatever encoding appropriate

answered Aug 01 '17 at 11:50

Jess

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score 1 · Answer 8 · edited Jun 20 '20 at 09:12

Unsure of data's encoding type? No problem!

Without need to know potential encoding types, in which wrong encoding types will give you nil/null, this should cover all your bases:

NSString *dataString = [data base64EncodedStringWithOptions:NSDataBase64EncodingEndLineWithCarriageReturn];

Done!

Note: In the event this somehow fails, you can unpack your NSData with NSKeyedUnarchiver , then repack the (id)unpacked again via NSKeyedArchiver, and that NSData form should be base64 encodeable.

id unpacked = [NSKeyedUnarchiver unarchiveObjectWithData:data];
data = [NSKeyedArchiver archivedDataWithRootObject:unpacked];

score 0 · Answer 9 · answered Jul 02 '20 at 14:58

Objective C includes a built-in way to detect a the encoding of a string embedded in NSData.

NSData* data = // Assign your NSData object...

NSString* string;
NSStringEncoding encoding = [NSString stringEncodingForData:data encodingOptions:nil convertedString:&string usedLossyConversion:nil];

Ashok R · Answer 10 · 2017-04-19T17:08:12.373

-2

in objective C:

NSData *tmpData;
NSString *tmpString = [NSString stringWithFormat:@"%@", tmpData];
NSLog(tmpString)

edited Apr 19 '17 at 17:08

answered Apr 19 '17 at 17:03

Ashok R

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this one is wrong, it will return something like ```{length = XX, bytes = 0xYYYYYYYY}``` and I assume question was how to unwrap encoded string from raw bytes, not their description – raistlin Apr 09 '20 at 14:06

Converting NSData to NSString in Objective c

10 Answers10

Unsure of data's encoding type? No problem!

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