How do I get red green blue (RGB) and alpha back from a UIColor object?

The reason for the crash when accessing SelectedColor.CGColor could be that you do not retain the result from getColor, perhaps what you need is:

SelectedColor = [[(ColorPickerView *)alertView getColor] retain];

You can only get the RGB color component from a UIColor that is using the RGB color space, since you are using colorWithRed:green:blue:alpha: that is not a problem, but be vary of this if your code changes.

With this is mind getting the color components is really easy:

const CGFloat* components = CGColorGetComponents(SelectedColor.CGColor);
NSLog(@"Red: %f", components[0]);
NSLog(@"Green: %f", components[1]); 
NSLog(@"Blue: %f", components[2]);
NSLog(@"Alpha: %f", CGColorGetAlpha(SelectedColor.CGColor));