iphone - 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, &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.

Answer 1

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