Previously I was using Mycelium, however I encountered a bug twice where I scanned a QR code, and the Mycelium wallet sent the payment TWICE! The first time I thought maybe I did something wrong, but the second time I was certain that it was the wallet. I found this completely unacceptable and immediately started looking for a new iOS mobile wallet.
I noticed that too on Mycelium, right after paying a QR-code, Mycelium still shows the option to send the payment. I've seen it twice, but didn't click it so didn't send it twice.