The iPhone 6s specs say it can record 720p video at 240 fps and 1080p video at 120 fps. A friend tells me he bought a replacement camera for US$8, including the flex cable, but it was the front camera, which is only 60fps for 720p.
iPhone cameras are well-known for their rolling-shutter feature, where they scan each line of the image out at a separate time during the frame, leading to visual distortions of rapidly moving objects rather than blur, at least when light is adequate. So rather than considering the back camera as a 240fps camera, it may be reasonable to consider it as a 172800-line-per-second camera, although the gating time (shutter speed) for each line might actually be longer than the 5.8 μs suggested there. Robert Elder reports success recording 660 frames per second on a US$6 Raspberry Pi camera and 1007 frames per second on the V2 camera by reading out the same lines over and over again (so you get a smaller frame at a higher frame rate) but alternatives include using a glass rod to defocus the camera in Y so that every line sees almost exactly the same image, or to use two parallel mirrors to kaleidoscopically replicate a small fraction of the field of view several times.
Streak cameras are an extremely important research tool for investigating all kinds of ultrafast phenomena, such as the time evolution of an arc in air.