Pictograph is the best steganographic app available for iOS. Send messages without anyone knowing.
Steganography is the practice of hiding messages in plain sight. Pictograph works by changing the least significant bits in each pixel in a specific way so that a message can be hidden. Because Pictograph only changes the least significant bits in a pixel, the change is imperceptible to human eyes.
AES-256 encryption is used in Pictograph when encryption is enabled. This encryption is incredibly hard to break, so rest assured your message will be safe if you choose to encrypt it.