Memory Question?

[jonthornham]

I am trying to figure out if a step is necessary.

If I create an object which has an NSArray object as a property, and I specify a retain in the accessor methods.

Code: (Objective-C)

#import <UIKit/UIKit.h>

@interface CellsViewController : UIViewController <UITableViewDataSource, UITabeViewDelegate>
{
	NSArray *computers;
}

@property (nonatomic, retain) NSArray *computers;

@end

When I get to the viewDidLoad method I do the following.

Code: (Objective-C)

- (void)viewDidLoad 
{
    NSDictionary *row1 = [[NSDictionary alloc] initWithObjectsAndKeys: @"MacBook", @"Name", @"White", @"Color", nil];
    NSDictionary *row2 = [[NSDictionary alloc] initWithObjectsAndKeys: @"MacBook Pro", @"Name", @"Silver", @"Color", nil];
    NSDictionary *row3 = [[NSDictionary alloc] initWithObjectsAndKeys: @"iMac", @"Name", @"White", @"Color", nil];
    NSDictionary *row4 = [[NSDictionary alloc] initWithObjectsAndKeys: @"Mac Mini", @"Name", @"White", @"Color", nil];
    NSDictionary *row5 = [[NSDictionary alloc] initWithObjectsAndKeys: @"Mac Pro", @"Name", @"Silver", @"Color", nil];
    
    NSArray *array = [[NSArray alloc] initWithObjects:row1, row2, row3, row4, row5, nil];
    
    self.computers = array;
    
    [row1 release]; 
    [row2 release]; 
    [row3 release]; 
    [row4 release]; 
    [row5 release]; 
    [array release];
}

I am creating a temporary NSArray named array which I use to set the object array.

Code: (Objective-C)

self.computers = array;

When the array object is set the objects in the array and the array itself are retained which is why I can release all of them in the method. My question has to do with the temporary array. Could I do the following or am I missing something?

Code: (Objective-C)

self.computers = [[NSArray alloc] initWithObjects:row1, row2, row3, row4, row5, nil];

That way I would not have to create or release the array just the NSDictionary's. I understand the first option looks really clean I am just trying to see if I understand.

Thanks,

Jon
   
 

[rgronlie]

Jon,

Code: (Objective-C)

self.computers = [[NSArray alloc] initWithObjects:row1, row2, row3, row4, row5, nil];

I believe you'll end up with self.computers having a retain count of 2 since you did the alloc yourself (retain count 1) and then you have the retain property (retain count +1) for computers. This would mean a memory leak occurs after you try to release computers.

I would use autorelease on the array.

Code: (Objective-C)

self.computers = [[[NSArray alloc] initWithObjects:row1, row2, row3, row4, row5, nil] autorelease];

or

Code: (Objective-C)

self.computers = [NSArray arrayWithObjects:row1, row2, row3, row4, row5, nil];

Ryan

[jonthornham]

Thanks, Ryan I see exactly what you're saying.

Take care,

Jon