NSData initWithBytesNoCopy length freeWhenDone example in Objective C (iOS).

NSData initWithBytesNoCopy length freeWhenDone

Initializes a newly allocated data object by adding to it length bytes of data from the buffer bytes.

- (id)initWithBytesNoCopy:(void *)bytes length:(NSUInteger)length freeWhenDone:(BOOL)flag

Parameters of [NSData initWithBytesNoCopy length freeWhenDone]
bytes
A buffer containing data for the new object. If flag is YES, bytes must point to a memory block allocated with malloc.
length
The number of bytes to hold from bytes. This value must not exceed the length of bytes.
flag
If YES, the returned object takes ownership of the bytes pointer and frees it on deallocation.

NSData initWithBytesNoCopy length freeWhenDone example.

int offset = 10;
NSRange dataRange;
dataRange.length = [data length] - offset;
dataRange.location = offset;

void *buffer = malloc(dataRange.length);
[data getBytes:buffer range:dataRange];
self.bodyData = [[NSData alloc] initWithBytesNoCopy:buffer length:dataRange.length];
free(buffer); //Make sure your property has either retain attribute (or strong if using ARC)

Example of [NSData initWithBytesNoCopy length freeWhenDone].

if (flags == nil) {
   flagPtr *flgH = &flags;
   NSData *flgsDatum =
      [[NSData alloc] initWithBytesNoCopy:flgH length:sizeof(flgH)
freeWhenDone:NO];
   [[NSNotificationCenter defaultCenter] postNotificationName:@"fetchFlags"
object:flgsDatum];
   *flags = (WORKING | (*flags & LOGFILE));
}

NSData initWithBytesNoCopy length freeWhenDone example.

- (NSString *)hashWithDigest:(AUMessageDigest)digest data:(NSData **)data
{
    u_byte *(*CC_XXX)(const void *, CC_LONG, u_byte *);
    CC_LONG CC_XXX_DIGEST_LEN;
    u_byte *md = NULL;
    NSInteger i = 0;
    NSString *result;
    NSMutableString *buffer;
   
    switch (digest) {
        case AUDigestSHA1:
            CC_XXX = CC_SHA1;
            CC_XXX_DIGEST_LEN = CC_SHA1_DIGEST_LENGTH;
        break;
        case AUDigestSHA256:
            CC_XXX = CC_SHA256;
            CC_XXX_DIGEST_LEN = CC_SHA256_DIGEST_LENGTH;
        break;
        case AUDigestSHA512:
            CC_XXX = CC_SHA512;
            CC_XXX_DIGEST_LEN = CC_SHA512_DIGEST_LENGTH;
        break;
        case AUDigestMD5:
            CC_XXX = CC_MD5;
            CC_XXX_DIGEST_LEN = CC_MD5_DIGEST_LENGTH;
        break;
        default:
            return nil;
    }
   
    result = nil;
    if((md = malloc(CC_XXX_DIGEST_LEN * sizeof(u_byte) + 1))) {
        memset(md, 0, CC_XXX_DIGEST_LEN + 1);
        CC_XXX([self bytes], [self length], md);
        buffer = [NSMutableString string];
        for (i = 0; i< CC_XXX_DIGEST_LEN; i++) {
            [buffer appendFormat:@"%02x", (CC_LONG)(md[i])];
        }
        if (data != nil) {
            *data = [[NSData alloc] initWithBytesNoCopy:md length:CC_XXX_DIGEST_LEN freeWhenDone:YES];
        } else {
            free(md);
        }
        result = [NSString stringWithString:buffer];
    }
    return result;
}

End of NSData initWithBytesNoCopy length freeWhenDone example article.