i try to understand initializers in obj-c and i can't - objective-c

Question

I try to understand how to work simple init funcion and I don't know where I have made a mistake. Can somebody assist?
Rectangle.h
#interface Rectangle : NSObject
{
int width;
int height;
}
-(id)initObject;
#end
Rectangle.m
#implementation Rectangle
-(id)initObject{
if (self = [super init]) {
height = 5;
width = 7;
}
return self;
}
#end
And in ViewController.h i import Rectangle.h, declare *rect object and in .m i execute(? run?) initObject.
ViewController.h
#import <UIKit/UIKit.h>
#import "Rectangle.h"
#interface ViewController : UIViewController
{
Rectangle *rect;
}
#end
ViewController.m
-(void)viewDidLoad
{
rect = [[Rectangle alloc] initObject];
NSLog(#"%#", rect);
[super viewDidLoad];
}
initObject return me:
2011-11-21 09:43:02.625 initializers[43693:f803] <Rectangle: 0x6ab1660>

Answer 1

The only problem with your code that I can see is you called your initializer -initObject for no good reason. It's not taking any parameters at all, so you really should just call it -init like every other parameterless initializer in the system.
As for the log output, I imagine your confusion lies in the fact that it says <Rectangle: 0x6ab1660>. This is perfectly normal. The default implementation of -description (the method that returns this output) is the name of the class of the object followed by the object's address. In other words, -[NSObject description] is likely to be implemented something like the following:
- (NSString *)description {
return [NSString stringWithFormat:#"<%#: %p>",
NSStringFromClass([self class]),
self];
}
This means that instance variables of your object are not going to be printed. A number of built-in classes do print their instance variables when logged, but this was implemented specifically for that class and is not a generic mechanism. If you want to verify that your Rectangle object is correct, you could implement -description like so:
- (NSString *)description {
return [NSString stringWithFormat:#"<%#: %p width=%d, height=%d>",
NSStringFromClass([self class]),
self,
width,
height];
}

Answer 2

No error! Since your Rectangle class has no description method, calling NSLog(#"%#", rect); will return the class of the object, followed by its address in memory.
If you want to print width and height of the rectangle you may use something like:
in Rectangle.h
#interface Rectangle : NSObject
{
int width;
int height;
}
-(id)initObject;
#property int width, height;
#end
in Rectangle.m
#implementation Rectangle
#synthesize width, height;
-(id)initObject{
if (self = [super init]) {
height = 5;
width = 7;
}
return self;
}
#end
and then call
NSLog(#"width=%d, height=%d", [rect width], [rect height]);