So just to answer the question so i can use code and everything..
I changed the EncryptedText in the Data Model to Binary Data and then the code would look like this:
uint8_t *cipherBuffer = NULL;
SecKey *encrypt = [[SecKey alloc]init];
[encrypt generateKeyPairRSA];
cipherBuffer = [encrypt Encryption:plainTextField.text];
NSMutableData *data = [[NSMutableData alloc]init];
[data appendBytes:cipherBuffer length:strlen((char*)cipherBuffer)+1];
// Save cipher into the Data Model
[self.currentNote setEncryptedText:data];
[self.delegate addNewNoteViewControllerDidSave];
// Retrieve cipher back from Data Model
NSData *etData = [[NSData alloc]init];
etData = [self.currentNote encryptedText];
// Convert back to uint8_t
const void *bytes = [etData bytes];
uint8_t *crypto_data = (uint8_t*)bytes;
// De cypher
[encrypt Decryption:crypto_data];