Focos

TTTT.  (Tint Tussocks Terrific Tips)
Yes I know that the spelling is wrong. Its an App.... Focos..... It lets you use (35mm equivalent) F2,8 on an iPhone or for that matter any F Stop you like and have the background beautifully out of focus (or not)  and you can even play with it afterwards., Please remember that the same rules apply, especially if you are  doing  a close up. Hold STILL. Because movement will give you iPhone shake and an unsharp image. Folk often confuse unsharpness with bad focus but its more often than not, camera shake with a shutter speed that was not fast enough to freeze any  movement.
Tiny