iOS - enable null iv

Author: Patrik Majerčík

ios/RCTAes/lib/AesCrypt.m

@@ -75,7 +75,7 @@ + (NSData *) AES256CBC: (NSString *)operation data: (NSData *)data key: (NSStrin
                                           kCCAlgorithmAES128,
                                           kCCOptionPKCS7Padding,
                                           keyData.bytes, kCCKeySizeAES256,
-                                          ivData.bytes,
+                                          ivData.length ? ivData.bytes : nil,
                                           data.bytes, data.length,
                                           buffer.mutableBytes,  buffer.length,
                                           &numBytes);