iOS lets you choose between a 4 digit pin or an alphanumeric password of whatever length you want. The 4 digit pin is meant to be more convenient, but even then

iOS lets you choose between a 4 digit pin or an alphanumeric password of whatever length you want. The 4 digit pin is meant to be more convenient, but even then most smartphone owners don't use it. The point of TouchID was to have a more secure default for most than a 4 digit pin or, more commonly, no pin or password at all. Few people would be happy with having to enter a 12+ character alphanumeric password each time they wanted to use their phone, you're an outlier there.