Question

Until five minutes I was sure that my understanding about Objective c reference counting is excellent, but when I started checking objects retainCount I was very surprised to see what I saw.

For example myViewController has a UITableview:

.h file

@interface RegularChatViewController : UIViewController <UITableViewDataSource, UITableViewDelegate>
{
     UITableView *_tableView;
}
@property (nonatomic, retain) IBOutlet UITableView *tableView; 

.m file

@synthesize tableView = _tableView;

- (void)loadView
{
    _tableView = [[UITableView alloc] init];  // STEP ONE
    NSLog(@"tableView retain count: %d",[_tableView retainCount]);

    self.tableView.frame = CGRectMake(0, 0, 320, tableHeight); // STEP TWO
    NSLog(@"tableView retain count: %d",[_tableView retainCount]);  

    [self.view addSubview:self.tableView]; // STEP THREE
    NSLog(@"tableView retain count: %d",[_tableView retainCount]); 
}

To my surprise the input was:

tableView retain count: 1
tableView retain count: 2
tableView retain count: 3

obviously STEP ONE increase retain count by 1 with alloc

I also know that STEP THREE increase retain count by 1 with addSubview

But whats going on in STEP TWO ??? why did it increase the retain count???
is there something to do with ARC??

Answer 1

According to Apple docs on NSObject Protocol Reference for the retainCount method:

Important This method is typically of no value in debugging memory management issues. Because any number of framework objects may have retained an object in order to hold references to it, while at the same time autorelease pools may be holding any number of deferred releases on an object, it is very unlikely that you can get useful information from this method.