Question

In my constructor, I want to create a random color.

Therefore, I need three random 7-bit floats in the range of 0…1 that make up the red, green and blue component of the color. Instead of writing the rather long random() % 128 / 128.0 three times, I put that in a block:

CGFloat (^randFloat)() = ^(){ return random() % 128 / 128.0; };
color = CGColorCreateGenericRGB(randFloat(), randFloat(), randFloat(), .5);

Is that a valid way to use blocks?
If not, what would you use instead?

Answer 1

Are you going to return randFloat? Will randFloat use any states not separable from the nearby functions (i.e. is randFloat a closure)? If not, it’s more portable (the iPhone official SDK doesn’t support blocks yet, for example) and efficient to create a static function outside of the function:

static CGFloat randFloat() {
    return random() % 128 / 128.0;
}
...
color = CGColorCreateGenericRGB(randFloat(), randFloat(), randFloat(), .5);