nsdata

This is my function. First println print correct hash to console but in the next row program crashes. Can you help me? func sha256(string: NSString) -> NSString { var data : NSData! = string.dataUsingEncoding(NSUTF8StringEncoding) var hash = [UInt8](count: Int(CC_SHA256_DIGEST_LENGTH), repeatedValue: 0) CC_SHA256(data.bytes, CC_LONG(data.length), &hash) let res = NSData(bytes: hash, length: Int(CC_SHA256_DIGEST_LENGTH)) println(res) let resstr = NSString(data: res, encoding: NSUTF8StringEncoding) println(resstr) return resstr } let resstr = NSString(data: res, encoding: NSUTF8StringEncoding)

When reading an NSString from a file I can use initWithContentsOfFile:usedEncoding:error: and it will guess the encoding of the file. When I create it from an NSData though my only option is initWithData:encoding: where I have to explicitly pass the encoding. How can I reliably guess the encoding when I work with NSData instead of files? In general, you can’t. However, you can quite reliably identify UTF-8 files – if a file is valid UTF-8, it’s not very likely that it’s supposed to be any other encoding (except if all the bytes are in the ASCII range, in which case any “extended ASCII”

What's currently working in my code: I select a JPG or PNG from the Photo Library (using standard ImagePicker methods), and convert that image to NSData using: self.myImageData = UIImageJPEGRepresentation(myImage, 0.9); which I then post to a server using multipart/form-data. I now want to do the same for a GIF, while retaining the original GIF data (so that an animated GIF going into the library, comes back out still animating). In didFinishPickingMediaWithInfo, I am able to get the URL of the original GIF using self.myGIFURL = [info objectForKey:UIImagePickerControllerReferenceURL]. Here's

I've an NSData object, the length is 4 bytes .These four bytes i'm extracting from another NSData object using , fourByteData=[completeData subdataWithRange:NSMakeRange(0, 16)]; My first question is, will the above statement provide me the first four bytes of complete data. If Yes, then how to convert all these bytes to an equivalent int. Is 268566528 the value you expect or perhaps you expect 528? If the correct value is 528 then the byte order is big-endian but the cpu is little-endian, the bytes need to be reversed. So, if the correct value should be 528 then: NSData *data4 = [completeData

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: