Question

First of all, sorry for the amount of code.
What i’m doing wrong managing memory. I can’t understand why the analyzer throws a memory leak.

@interface obj : NSObject 
{
    NSMutableArray *array;
}
@property (retain, nonatomic) NSMutableArray *array;
@end

@implementation obj
@synthesize array;

- (id)init
{
    self = [super init];
    if (self) 
    {
        // Initialization code here.
        array = [[NSMutableArray alloc] init];
    }

    return self;
}

- (void)dealloc
{
    [super dealloc];
    [array release];
}

@end

int main (int argc, const char * argv[]) 
{
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    // insert code here...
    obj *test = [[obj alloc] init];
    NSNumber *numero = [[NSNumber alloc] initWithFloat:3.4];

    NSLog(@"Número: %g \n", [numero floatValue]);

    [test.array addObject:numero];

    NSLog(@"Numero de elementos: %lu", [test.array count]);

    NSLog(@"Valor: %g", [[test.array objectAtIndex:0] floatValue]);

    NSLog(@"Numero de elementos t2: %lu", [test.array count]);

    numero = [NSNumber numberWithFloat:5.8];

    NSLog(@"Valor t2: %g", [[test.array objectAtIndex:0] floatValue]);
    NSLog(@"Número t2: %g \n", [numero floatValue]);

    [test.array addObject:numero];    

    NSLog(@"Valor: %g", [[test.array objectAtIndex:0] floatValue]);

    [numero release]; **<-- Leak of memory**
    [test release];
    [pool drain];

    return 0;
}

Answer 1

Easy fix, you forgot to release the existing value before reassigning it.

// You created an instance of NSNumber here
NSNumber *numero = [[NSNumber alloc] initWithFloat:3.4];

// Then you reassigned it here without releasing it first which caused the leak HERE
numero = [NSNumber numberWithFloat:5.8];

[numero release]; **<-- Leak of memory**

You can get around this completely by using numberWithFloat in both instances which returns an autoreleased object.

NSNumber *numero = [NSNumber numberWithFloat:3.4];

numero = [NSNumber numberWithFloat:5.8];

// Now you don't need to release it at all ;)
//[numero release]; **<-- Leak of memory**

Or you can fix your existing example by:

NSNumber *numero = [[NSNumber alloc] initWithFloat:3.4];

[numero release];

numero = [NSNumber numberWithFloat:5.8];

// Remove this one since numberWithFloat returns an autoreleased object
//[numero release]; **<-- Leak of memory**