Question

Using ARC, is it now OK to assign a string value like this:

 self.userName = [[NSString alloc] initWithString:self.currentParsedCharacterData];

Or does that still cause a memory leak, thus requiring me to assign it like this:

NSString *tmpString = [[NSString alloc] initWithString:self.currentParsedCharacterData];
self.userName = tmpString;

Answer 1

The first snippet is just fine under ARC, and is the better of the two ways. Apple has an example like this in the Transitioning to ARC guide:

- (void)contrived {
    Person *aPerson = [[Person alloc] init];
    [aPerson setFirstName:@"William"];
    [aPerson setLastName:@"Dudney"];
    [aPerson setYearOfBirth:[[NSNumber alloc] initWithInteger:2011]];
    NSLog(@"aPerson: %@", aPerson);
}

and says:

ARC takes care of memory management so that neither the Person nor the NSNumber objects are leaked.

The setYearOfBirth: message with an alloced NSNumber corresponds to your snippet.

The compiler understands that, in the first case, aPerson is going out of scope and needs to be released before that happens, and, in the second case, that there is no explicit reference to the NSNumber object and that it must be either released or put into the autorelease pool. It takes care of both these requirements on your behalf.