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copied!<p>(1) You're accessing it correctly.</p> <p>(2) In objective-c 2.0, the assignments have identical affect. </p> <p>Design wise, you would want to make:</p> <pre><code>-(void) setPosX:(int) inPosX andPosY:(int) inPosY; </code></pre> <p>...into a method of Position. This encapsulates both the data and the methods related to into one object. So you could have calls like:</p> <pre><code>coord = [[Position alloc] initWithX:inPosX andY:inPosY]; </code></pre> <p>or [coord setPosX:inPosX andPosY:inPosY];</p> <p>all much cleaner and easier to maintain.</p> <hr> <p>Edit O1</p> <blockquote> <p>Do I then call -(id)initWithX:andY: from the Rectangle object when I init it?</p> </blockquote> <p>That depends on your design. If the <code>coord</code> property is absolutely vital to the <code>Rectangle</code> instance, then you should call it when you initialize a <code>Rectangle</code> instance. You might even write an initializers for <code>Rectangle</code> that takes a position or x and y as input. eg:</p> <pre><code>-(id) initWithPosition:(Position *) aPos { self = [super init]; if (self) { NSLog(@"_init: %@", self); coord = aPos; // Released in dealloc (not shown) } return self; } </code></pre> <p>You should also write a connivence initializer for the Position class:</p> <pre><code>-(id) initWithX:(NSInteger) x andY:(NSInteger) y{ self=[super init]; self.posX=x; self.posY=y; return self; } </code></pre> <p>You would then call like:</p> <pre><code>Position *aPos=[[Position alloc] initWithX:100 andY:50]; Rectangle *aRec=[[Rectangle alloc] initWithPosition:aPos]; </code></pre> <p>Or you could write another combination initializer for Rectangle:</p> <pre><code>-(id) initWithXCoordinate:(NSInteger) x andYCoordinate:(NSInteger) y{ self=[super init]; Position *aPos=[[Position alloc] initWithX:x andY:y]; self.coord=aPos; return self; } </code></pre> <p>and call it like:</p> <pre><code>Rectangle *aRec=[[Rectangle alloc] initWithXCoordinate:100 andYCoordinate:50]; </code></pre> <p>These are rough examples but you get the idea. Objective-c gives you a lot of flexibility in setting up initializer so you can create any initializers you find convenient. </p> <p>You do generally want to avoid using actual functions instead of methods inside classes. </p>

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