Without those two mask types Pixelmator iOS is somewhat quite useless for what designers in 2016 do.
I can only use it for maybe working on some images or doing mask tests with duplicating layers and erasing
In the end I have to redo all the work then on the Mac making Pixelmator iOS an advanced version of Apple Photo
but rendering it unusable for designers.
So please add those two functions, they are a must have and foundation.