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up vote -3 down vote favorite

So I am new to Objective-C but not to OOP programming. I am trying to make a class that will add "Squares" to a NSMutableArray but when I wrote the class and ran my app, it crashed. Here is the Squares.h file:

#import <Foundation/Foundation.h>
#import "Square.h"

@interface Squares : NSObject {
    NSMutableArray *squares; }

-(id) init;
-(void) addSquare: (CGPoint) pos;
-(NSMutableArray *) getSquares;
-(void) update;
-(void) render;

@end

And here is the Squares.m file:

import "Squares.h"

@implementation Squares

-(id) init{ self = [super init]; if (self != nil) { squares = [[NSMutableArray alloc] init];

[self addSquare: CGPointMake(100, 100)];
      }
  return self; }

-(void) addSquare: (CGPoint) pos{ Square *square; square = [[Square alloc] init]; [square setPosition: pos];

[squares addObject: square]; }

-(NSMutableArray *) getSquares{ return squares; }

-(void) update{ for (int i = 0; i < squares.count; i++){ Square *s; s = [squares objectAtIndex: i]; [s move];

} }

-(void) render{ for (int i = 0; i < squares.count; i++){ Square *s; s = [squares objectAtIndex: i]; [s render];

} }

@end

So is this not working just because I have programmed this wrong or not?

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closed as not constructive by H2CO3, hypercrypt, Abizern, Mehul, Gabriele Petronella Apr 13 '13 at 17:30

As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. If this question can be reworded to fit the rules in the help center, please edit the question.
2  
Pffff.... So much errors. E. g., you're confusing pointers with the memory they're point to. You don't need that lonely poor [Square alloc], you just waste your user's RAM... –  user529758 Aug 14 '12 at 17:50
    
Indeed, the [Square alloc]s in your update and render functions do nothing of value. If you've got ARC on, they're just wasted cycles (unless the compiler manages to remove them, but either way, it's a waste). If you don't have it on, you've got a memory leak. –  nil Aug 14 '12 at 17:57
    
Ok so I made some changes. The game Runs now, but the square update method isn't working. THe render method is though. –  iOS_Master Aug 14 '12 at 18:34
    
Never mind. I forgot to add one more line of code to fix it. –  iOS_Master Aug 14 '12 at 18:38
    
Well, now the code block is unreadable again.. –  nil Aug 14 '12 at 19:44

2 Answers 2

up vote 2 down vote accepted

Instead of for (int i = 0; i <= squares.count; i++

try for (int i = 0; i < squares.count; i++

share|improve this answer
    
Ok, I tried that and the other suggestions. The game now runs and the square is rendering, but not moving!? –  iOS_Master Aug 14 '12 at 18:36
    
Never mind. I forgot to add one more line of code to fix it. –  iOS_Master Aug 14 '12 at 18:37
up vote 0 down vote

As others have pointed out, Square *s = [Square alloc]; in the update and render methods is useless.

As Andrey told you, for (int i = 0; i <= squares.count; i++) will count one too far, you should use < instead of <=.

Better yet just do:

-(void) update{
    [squares makeObjectsPerformSelector:@selector(move)]; }

-(void) render{
    [squares makeObjectsPerformSelector:@selector(render)]; }
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