如何释放手动保留的类对象

Question

I am working on a Tab Bar based application I have a class A with its .xib and a class B with its .xib

On class A i am loading multiple instances of class B.

ie In class A ,i am doing.

in .m file

   -(void)renderData:(NSArray *)Data
    {
         for(int i=0;i<[Data count];i++)
            {
               B *grid=[[B alloc]initWithNibName:@"Beta" bundle:[NSBundle mainBundle]];
               .
               .
               . //do something with the grid object i.e assign new image etc..)
               [self.myGrid addObject:grid]; //i have a NSMutableArray myGrid declared in .h
               [grid release];  
            }
    }

now in the myGrid Array i have all the objects of the grid saved.

Now i am adding them to the class Aplha view.

    for(int i=0;i<[myGrid count];i++)
      {
        B *grid1=[[myGrid objectAtIndex:i]retain]; //i have done this retain because when i try to come back to this tab or try to call the same function it crashes by saying message send to deallocated instance.
        [self.view addSubview:grid1.view];
       }

now my problem is that how to release the grid1 object that i have retained.

Answer 1

You are approaching this wrong. The problem here isn't how to release the grid1 object, it's why you are retaining them in the first place. You most likely shouldn't be; you need to investigate the original crash more thoroughly.

If your grid1 objects are stored in self.myGrid then they are retained by that array. Are you releasing myGrid anywhere? As long as that is retained, your grid1 objects should be.

In addition, there are some conceptual issues here. Loading a view controller from a nib and adding it's view as a sub-view of another view controller's view is generally not correct. It's hard to recommend the correct approach without knowing exactly what you are trying to achieve though.

You do not need to pass in [NSBundle mainBundle] to initWithNibName:bundle: - you can simply pass in nil as the default behaviour is to use the main bundle.

Your comment says you have "assigned" an NSMutableArray in your header. You don't assign anything in your header, you just declare things. Have you actually initialised the NSMutableArray somewhere in your implementation?

Answer 2

• You own any object you create when

You create an object using a method whose name begins with “alloc”, “new”, “copy”, or “mutableCopy” (for example, alloc, newObject, or mutableCopy).

• When you no longer need it, you must relinquish ownership of an object you own

You relinquish ownership of an object by sending it a release message or an autorelease message. In Cocoa terminology, relinquishing ownership of an object is therefore typically referred to as “releasing” an object.

To release grid1 use [grid1 release];

---

Note: There is no reason to retain/release your grid1 object in cycle. Just

B *grid1 = (B*)[myGrid objectAtIndex:i];
[self.view addSubview:grid1.view];

I don't know what happened with your rest code but it looks like you have some memory leaks in another place.