Convert NSData to String

Question

I am storing a openssl private Key EVP PKEY as nsdata  For this I am serializing into a byte stream using the code below  unsigned char  buf   p  int len  len   i2d PrivateKey pkey  NULL   buf   OPENSSL malloc len    p   buf  i2d PrivateKey pkey   amp p     where pkey  is of type EVP PKEY  Then I am storing the bytes from buffer  p  as an NSData using the line given below  NSData  keydata    NSData dataWithBytes P length len     Now I am converting it to a NSString using the code given below but when i print it into console its giving some other characters   NSString  content    NSString stringWithCString  keydata bytes  encoding NSUTF8StringEncoding     Could someone help       Basically I want to store the EVP PKEY   into a sqlite database   am I on the right track  Thanks

User · Accepted Answer

Objective-C You can use  see NSString Class Reference  -  id initWithData  NSData   data encoding  NSStringEncoding encoding  Example  NSString  myString     NSString alloc  initWithData myData encoding NSUTF8StringEncoding    Remark  Please notice the NSData value must be valid for the encoding specified  UTF-8 in the example above   otherwise nil will be returned   Returns nil if the initialization fails for some reason  for example if data does not represent valid data for encoding    Prior Swift 3 0 String data  yourData  encoding  NSUTF8StringEncoding   Swift 3 0 Onwards String data  yourData  encoding   utf8   See String init data encoding   Reference

User · Answer

Swift 3   String data  data  encoding   utf8

User · Answer

I believe your  P  as the dataWithBytes param  NSData  keydata    NSData dataWithBytes P length len     should be  buf   NSData  keydata    NSData dataWithBytes buf length len     since i2d PrivateKey puts the pointer  to the output buffer p at the end of the buffer and waiting for further input  and buf is still pointing to the beginning of your buffer   The following code works for me where pkey is a pointer to an EVP PKEY   unsigned char  buf   pp  int len   i2d PrivateKey pkey  NULL   buf   OPENSSL malloc len    pp   buf  i2d PrivateKey pkey   amp pp    NSData  pkeyData    NSData dataWithBytes  const void   buf length len   DLog   Private key in hex   d        len  pkeyData     You can use an online converter to convert your binary data into base 64  http   tomeko net online tools hex to base64 php lang en  and compare it to the private key in your cert file after using the following command and checking the output of mypkey pem   openssl pkcs12 -in myCert p12 -nocerts -nodes -out mypkey pem   I referenced your question and this EVP function site for my answer

User · Answer

A simple way to convert arbitrary NSData to NSString is to base64 encode it     NSString  base64EncodedKey    keydata base64EncodedStringWithOptions  NSDataBase64Encoding64CharacterLineLength     You can then store it into your database for reuse later   Just decode it back to NSData

User · Answer

Prior Swift 3 0    String data  yourData  encoding  NSUTF8StringEncoding    For Swift 4 0   String data  yourData  encoding   utf8

User · Answer

Swift 5  String data  data   encoding  String Encoding utf8

[iphone] Convert NSData to String?

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