Strange problem comparing floats in objective-C

Question

At some point in an algorithm I need to compare the float value of a property of a class to a float. So I do this:

if (self.scroller.currentValue <= 0.1)          


        

Answer 1

0.1 is actually a very dificult value to store binary. In base 2, 1/10 is the infinitely repeating fraction

0.0001100110011001100110011001100110011001100110011...

As several has pointed out, the comparison has to made with a constant of the exact same precision.