NSString memory management question

• Rick Mann NSString memory management question Apr 23 2008, 00:25
  I wrote a routine that creates a CFStringRef from some USB calls. I
  use it like this:
  
  NSString* s = (NSString*) createStringDescriptor(dev, stringIndex);
  [mSerialNumberDisplay setStringValue: [s lowercaseString]];
  [s release];
  
  Two main questions: am I right to release the bridged NSString* s?
  and, what happens in -lowercaseString? How does that get released?
  
  TIA,
  --
  Rick
• Shawn Erickson Re: NSString memory management question Apr 23 2008, 00:51
  On Tue, Apr 22, 2008 at 3:25 PM, Rick Mann <rmann...> wrote:
  

  > I wrote a routine that creates a CFStringRef from some USB calls. I use it
  > like this:
  >
  > NSString* s = (NSString*) createStringDescriptor(dev, stringIndex);
  > [mSerialNumberDisplay setStringValue: [s lowercaseString]];
  > [s release];
  >
  >
  > Two main questions: am I right to release the bridged NSString* s? and,
  

  
  We don't know how you created the CFStringRef so we cannot say. The
  answer depends on the create/get rule of the Core Foundation method
  you used. Additionally it depends on the contract you want to present
  to clients for the createStringDescriptor.
  
  

  > what happens in -lowercaseString? How does that get released?
  

  
  Review...
  
  <http://developer.apple.com/documentation/Cocoa/Conceptual/MemoryMgmt/Tasks/
  MemoryManagementRules.html>
  
  -Shawn
• Rick Mann Re: NSString memory management question Apr 23 2008, 01:08
  On Apr 22, 2008, at 3:51 PM, Shawn Erickson wrote:
  
  

  > We don't know how you created the CFStringRef so we cannot say. The
  > answer depends on the create/get rule of the Core Foundation method
  > you used. Additionally it depends on the contract you want to present
  > to clients for the createStringDescriptor.
  

  
  Sorry, I thought saying "created" was clear. I actually call a
  CreateXXX function.
  
  

  >> what happens in -lowercaseString? How does that get released?
  >
  > Review...
  >
  > <http://developer.apple.com/documentation/Cocoa/Conceptual/MemoryMgmt/Tasks/
  MemoryManagementRules.html
  

  > >
  
  Okay, I think from that, the string is automagically freed. Thanks!
  
  --
  Rick
• Uli Kusterer Re: NSString memory management question Apr 23 2008, 02:46
  Am 23.04.2008 um 00:25 schrieb Rick Mann:
  
  

  > I wrote a routine that creates a CFStringRef from some USB calls. I
  > use it like this:
  >
  > NSString* s = (NSString*) createStringDescriptor(dev, stringIndex);
  > [mSerialNumberDisplay setStringValue: [s lowercaseString]];
  > [s release];
  >
  > Two main questions: am I right to release the bridged NSString* s?
  > and, what happens in -lowercaseString? How does that get released?
  

  
    Calling release on a CFString follows the same rules as calling it
  on an NSString*, and is equivalent to calling CFRelease(). Be careful,
  though, if you get a CFString or OSString from IOKit ... someone there
  apparently wasn't told about the rules in the rest of
  CoreFoundation... they don't follow the Create/Copy naming scheme
  consistently, and instead have weird phrases in the docs about
  "consuming a refcount" and things like that.
  
    But apart from that, the rules in the CoreFoundation docs apply, so
  assuming you're using a CFStringCreateXXX call, yes, you should
  release this string.
  
  Cheers,
  -- Uli Kusterer
  "The Witnesses of TeachText are everywhere..."
  http://www.zathras.de
• Rick Mann Re: NSString memory management question Apr 23 2008, 02:50
  On Apr 22, 2008, at 5:46 PM, Uli Kusterer wrote:
  
  

  > But apart from that, the rules in the CoreFoundation docs apply, so
  > assuming you're using a CFStringCreateXXX call, yes, you should
  > release this string.
  

  
  Yeah, I was fairly sure about that one, it was the NSString -
  lowercaseString I wasn't sure about.
  
  --
  Rick