[Learning Cocoa Qs] View Hierarchy & Pointers to Cocoa data structures
[Learning Cocoa Qs] View Hierarchy & Pointers to Cocoa data structures
- Subject: [Learning Cocoa Qs] View Hierarchy & Pointers to Cocoa data structures
- From: Dale Gillard <email@hidden>
- Date: Sun, 8 Jul 2001 22:37:03 +1000
Hi all
I have 2 questions from the Learning Cocoa book I'm hoping people can
help me with:
QUESTION 1
Page 127 shows figure 8-3. It depicts the view hierarchy of a window
with 3 views: A, B and C. A is the window view containing views B and C.
What I don't understand is that the hierarchy has 2 NSWindows sitting
between the NSApplication and NSView 'A'. Shouldn't there only be 1
NSWindow?
QUESTION 2
OK. My second question relates to the Dot View project on pages 133 -
138. Page 135 contains example 8-1. It's code declaring a header file
for DotView, including these 2 variables:
NSPoint center;
NSColor *color;
My question is: why is one a variable, and the other a pointer to a
variable? Is this because the NSPoint class always returns an object of
NSPoint when it's created? And that the NSColor class returns a pointer
to a NSColour object when it is instantiated?
I've had a look in the Cocoa Help but can't find any info for NSPoint
(Objective C version). (There is a Java version of the help info in
Cocoa Help.) I've also had a look for and found the NSColor Cocoa Help
info. But I can't find where is says what is returned when an object of
this type is instantiated. That is, whether it's a pointer or a variable.
Am I missing something in the help documentation? Am I missingn
something in my knowledge of C (I've done some C++ at university). If
not, how do others know whether to declare a variable or a pointer to a
variable?
Many thanks for any help
Dale