One of the best things about iMessage is that you can use it to send and transfer videos and images using the service without it compressing the images to a point where they are nearly impossible to use. Hence, it may take a while to send images across using iMessage but given the high res quality that you receive, it is usually worth the time and wait.
However, these images, unlike Whatsapp are not saved in your system by default. Instead you have to long press on the image and then only does it save to the photo gallery. However, if you receive images often which are important from your friends and family and would like to save them up instantly without any intervention than MSGAutoSave is the perfect Cydia Tweak for you.
Obviously, you must be on a jailbroken iPhone to be able to use this tweak and download it from the Cydia Store. The tweak is available from insanelyi repo for absolute free. All you need to do is fire up Cydia and search for the tweak by its name and install it. You will be prompted to restart the springboard on your device and once you do that, go ahead and test out in the iMessage window of a friend, you will see that the photos will automatically be saved into the photo gallery as long as you have given permission for the app to access the gallery. You can obviously, enable or disable the tweak in the settings section of the tweak as well as add in a prompt message which will alert you whenever a photo is being saved, but that kind of kills the whole purpose doesn’t it?
Via: Addictive Tips