iPhone brightness private API not working properly

Question

I am trying to set the brightness of the backlight, but it\'s acting very strangely. I am using the private API:

[(id)[UIApplication sharedApplication] setBacklightL

Answer 1

The problem is that the compiler doesn't know a method takes a float unless you declare it. So the float you pass in is getting converted to another type when you pass it and then that new bit pattern being reinterpreted as a float by the method. You just need to have the method declared in a header that file knows about and the float will be passed unaltered.