How do you properly compose the #interface section? [closed] - objective-c

Question

Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
Closed 9 years ago.
Questions asking for code must demonstrate a minimal understanding of the problem being solved. Include attempted solutions, why they didn't work, and the expected results. See also: Stack Overflow question checklist
Questions concerning problems with code you've written must describe the specific problem — and include valid code to reproduce it — in the question itself. See SSCCE.org for guidance.
Improve this question
I am fairly new to Objective-C and created this basic program. It is giving me errors on the #interface section, is there any simple explanation that you could give a beginner on how to build both the #interface and #implementation sections? What is wrong with the program below?
#import <Foundation/Foundation.h>
#interface Rectangle : NSObject {
//declare methods
- (void) setWidth: (int) a;
- (void) setHieght: (int) b;
- (double) perimeter;
- (double) area;
}
#end
#implementation Rectangle
{
double area;
double perimeter;
int width;
int height;
}
- (void) setWidth: (int) a
{
width = a;
}
- (void) setHieght: (int) b
{
hieght = b;
}
#end
int main (int argc, const char * argv[])
{
NSAutoreleasePool * Rectangle = [[NSAutoreleasePool alloc] init];
int a = 4
int b = 5
int area = a * b;
int perimeter = 2 * (a +b);
NSLog(#"With width of %i and Hieght of %i", a, b);
NSLog(#"The perimeter is %i", perimeter);
NSLog(#"The Area is %i", area);
[pool drain];
return 0;
}

Answer 1

Your listing your methods where ivars are supposed to go. It should be:
#interface Rectangle : NSObject {
//instance variables here
}
// declare methods or properties here
- (void) setWidth: (int) a;
- (void) setHieght: (int) b;
- (double) perimeter;
- (double) area;
#end
You can, as has been pointed out, just simply delete the curly braces.

Answer 2

There are several problems in your code, we'll see them later, but as beginner you need to know few things:
main() is for main.m class in your project, don't mess-up with that here and there, use init() instead
you don't declare methods inside {} scope of your #implementaion
After #end of #implementation nothing that is to be execute should be written
#implementation shouldn't be bounded in {} scope as it end with #end
And some more, find it here http://www.slideshare.net/musial-bright/objective-c-for-beginners
So your should look like this:
#import <Foundation/Foundation.h>
#interface Rectangle : NSObject
//declare methods
- (void) setWidth: (int) a;
- (void) setHieght: (int) b;
- (double) perimeter;
- (double) area;
#end
#implementation Rectangle
    {
double area;
double perimeter;
int width;
int height;
    }
- (void) setWidth: (int) a {
width = a;
}
- (void) setHieght: (int) b {
height = b;
}
- (id)init
{
self = [super init];
if (self) {
// Custom initialization
int a = 4;
int b = 5;
int area = a * b;
int perimeter = 2 * (a +b);
NSLog(#"With width of %i and Hieght of %i", a, b);
NSLog(#"The perimeter is %i", perimeter);
NSLog(#"The Area is %i", area);
}
return self;
}
#end