Text Based Augmentative and Alternative Communication (AAC) apps have you type what you want to say. They use tools like word prediction or pictures to help you type. This is not a new type of app. However, more apps are being made with this theme. As a result, it gets a separate section.
Predictable
This is a high-end text-based communication app with good ratings. The app works with switches.
https://itunes.apple.com/us/app/predictable/id404445007?mt=8
https://play.google.com/store/apps/details?id=com.tbox.predictable_4&hl=en_US
Proloquo4Text
This is a very highly rated, high-end, text-based communication app.
https://itunes.apple.com/us/app/proloquo4text-text-based-aac/id751646884?mt=8
Text to Speech!
This is an iPad/iPhone app that says whatever you type. The is simply free and get the job done. The reviews are also pretty good.
https://itunes.apple.com/us/app/text-to-speech/id712104788
Verbally
This app has a good rating. You have to type what you are going to say. The app has a free version that gives you a better idea if you want this app.
https://itunes.apple.com/us/app/verbally-premium/id470081134?mt=8