StorySign first arrived in December but has been limited to the Android operating system until now.
The move on to iOS marks International Day of Sign Languages.
Deaf children often struggle to learn to read due to not being able to hear their parents read to them or hear a teacher repeating sentences, while there is no written form of sign language as there is no direct word-for-word translation.
The free app uses Huawei-developed artificial intelligence and a smartphone’s camera to recognise words on a page and translate them into sign language with an on-screen avatar designed by Wallace and Gromit-makers Aardman.
It currently features six books that support British Sign Language, including The Lonely Penguin, Max The Brave and All About Spot.
Huawei – which has worked on the project with charities such as the British Deaf Association and the European Union of the Deaf – said more than a third of people who have already downloaded the app on Android have become daily users.
“With the expansion of StorySign to new national sign languages, more deaf children than ever before will have access to this valuable learning resource,” said Joseph Murray, president of the World Federation of the Deaf.
“We look forward to working with Huawei on future projects around the world.”
Mark Wheatley, executive director of the European Union of the Deaf, said: “The support that we have received from Huawei to date has had a genuine impact on deaf children and their families.
“Through our ongoing partnership, we are continuing to work closely to ensure that StorySign reaches as many families and communities as possible, helping us get one step closer to our shared ambition of helping more deaf children learn to read.”
The National Deaf Children’s Society recently warned that deaf children are struggling at every stage of their education, with 44% of deaf pupils achieving two A-levels compared with 63% of hearing pupils, according to its own analysis of the Department for Education’s 2018 exam results for pupils up to the age of 19.
The charity wants Education Secretary Gavin Williamson to introduce a bursary to train hundreds of specialist teachers who can provide one-on-one support for deaf children, as well as their families and teachers, from diagnosis right through to the end of their education.