Question

Just wondering what the syntax would be to extract a CGFloat out of an NSDictionary like follows:

slider.minimumValue = [filterAttributes valueForKey:kCIAttributeSliderMin];

Answer 1

An NSDictionary only holds objects. What kind of object would wrap a primitive like CGFloat? NSNumber would make sense. Now, since CGFloat is either a float or a double, you’ll probably want to get the double value to preserve precision/range.

Therefore:

slider.minimumValue = [[filterAttributes valueForKey:kCIAttributeSliderMin] doubleValue];