问题
3D touch seems really cool and I wanted to see how it would work in a musical context. I was reading a bit about 3D touch and it seems like the force property almost always reads as 0 when a touch begins (touchesBegan method).
How do I get a usable force when a touch begins because even if I'm pressing with maximum "force" I'm still getting that initial 0? I was thinking about just approximating a value within a time frame but that would involve me moving the touch. I just want a usable force upon the first touch.
Thanks!
回答1:
Unfortunately this is impossible.
Every touch starts as a contact with no force at all, as soon as the user's finger makes contact (or even near-contact) with the screen. The force only starts to build as the user's finger is compressed against the screen.
The only way for touchesBegan: to report any force at all would be for it to delay artificially for a certain number of milliseconds before reporting a touch, to allow the force to build up. This would destroy the interactivity of all iOS applications; and Apple put a huge amount of work into delivering a touch the instant it is detected.
来源：https://stackoverflow.com/questions/38150111/uitouch-force-on-touchesbegan