Question

Today I read “Pro Objective-C Design Patterns for iOS” by Carlo Chung.
So I read about Adapter Pattern and saw this method declared in protocol:

-(void) command: (SetStrokeColorCommand *) command
        didRequestColorComponentsForRed: (CGFloat *) red
                                  green: (CGFloat *) green
                                   blue: (CGFloat *) blue;

You can see it on page 115 from book.
Than this method used

[delegate_ command:self didRequestColorComponentsForRed: &redValue
                                                  green: &greenValue
                                                   blue: &blueValue];

And then declaration of this method on page 118

-(void) command: (SetStrokeColorCommand *) command
        didRequestColorComponentsForRed: (CGFloat *) red
                                  green: (CGFloat *) green
                                   blue: (CGFloat *) blue
 {
  *red = [redSlider_ value];
  *green = [greenSlider_ value];
  *blue = [blueSlider_ value];
 }

What mean * in declaration (*red, *green, *blue) and what mean & (&redValue…)? I saw & with only &error in code.

Answer 1

* is the pointer declarator or dereference operator.
In a declaration, * denotes a pointer variable.

& is the address-of operator.

Side note:

You should learn the basics of a language before attempting more advanced books.