Re: Synthesize NSMutableString retain count question
Re: Synthesize NSMutableString retain count question
- Subject: Re: Synthesize NSMutableString retain count question
- From: Jens Alfke <email@hidden>
- Date: Wed, 3 Feb 2010 09:37:38 -0800
On Feb 3, 2010, at 3:55 AM, Philip Vallone wrote:
currentSection = @"Some value";
The retain count goes to 1
This assigns a new value to the pointer variable 'currentSection'. It
now points to the immutable string literal @"Some value".
However if I assign a value with
[currentSection setString:@"Some value"];
The retain count is still zero.
This tells the mutable string object that 'currentSection' currently
points to, to replace its contents with the characters in the string
@"Some value".
If you find the retain count is zero after this, it's probably because
the value of 'currentSection' is nil, i.e. it doesn't point to any
object. In that case the -setString: message is a no-op since messages
to nil are ignored, and -retainCount will return zero because messages
to nil always return 0/nil.
In general, it sounds as though you're unclear on the distinction
between an object and a pointer to an object. It's the same as structs
vs. pointers to structs in C, or for objects in C++; the difference is
that Objective-C objects can only be referred to by pointers (you
can't have a variable of type "NSString", only "NSString*".)
—Jens_______________________________________________
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