Question

Basic question here.

Say in my .h, I define a NSString:

@interface MyGreatClass
@property (nonatomic, retain) NSString *myAwesomeString;
@end

And then in my .m, I have the following code:

@implementation MyGreatClass
@synthesize myAwesomeString
-(void)dealloc{
    [myAwesomeString release];
}
-(void)viewDidLoad{
    self.myAwesomeString = [[NSString alloc] initWithString:@"Yay"];
}
@end

1. Did I leak? I know, I know, whenever you call retain or alloc
   on a method, it increases the counter in memory by one and you need
   to have a release statement for each retain and alloc, so I
   suspect I do, but I am just making sure because if this is true, I
   have to do this for a crapload of variables in my app. Also if you
   do have to call release twice, where do I call the second release?
   Can I call both of them in dealloc, one right after the other?

2. How nesesarry is the self. in front of variables when referring to properties of the class
   you are in? What happens if you don’t have it and when exactly is it
   necesarry?

Answer 1

Yes, that will leak because it’s overretained. The four standard correct solutions are:

// Solution 1:
NSString *stringToBeAwesome = [[NSString alloc] initWithString:@"Yay"];
self.myAwesomeString = stringToBeAwesome;
[stringToBeAwesome release];

//Solution 2:
self.myAwesomeString = [[[NSString alloc] initWithString:@"Yay"] autorelease];

// Solution 3:
self.myAwesomeString = [NSString stringWithString:@"Yay"];

// Solution 4:
myAwesomeString = [[NSString alloc] initWithString:@"Yay"];

You’ll notice the last one doesn’t start with self., which brings us to your second question. If you don’t write self., you are not accessing a property. That myAwesomeStirng in Solution 4 is an instance variable, accessed directly. It won’t go through the property accessors, so it won’t retain the value you assign and it won’t release any value that the variable held before.