Check out the trailer for Unsane. Not the first horror film shot on an IPhone but most certainly the one with the biggest budget.
From the Press Release
UNSANE is directed by Academy Award nominated director Steven Soderbergh (Logan Lucky, Erin Brockovich), stars Claire Foy (The Crown), Joshua Leonard (The Blair Witch Project), Jay Pharoah (Ride Along), Juno Temple (Atonement), Aimee Mullins (Stranger Things) and Amy Irving (Traffic).
A young woman leaves her hometown to escape a troubled past and begin a new job. But when she is involuntarily committed to a mental institution she is confronted by her greatest fear — but is it real or just her delusion? With seemingly no-one ready to believe her and the authorities unable or unwilling to help, she must confront her fears head on. With twisting perspectives and a shocking narrative, Unsane asks questions about our perception of reality, our survival instinct and the system that is supposed to take care of us.
UNSANE is released in cinemas across the USA, UK and Ireland on 23rd March 2018.