Question

NSArray     *path                   = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString    *documentsDirectory     = [path objectAtIndex:0];

NSString    *databasePath           = [documentsDirectory stringByAppendingPathComponent:@"DB"];
NSString    *fileName               = [newWordbookName stringByAppendingString:@".csv"];
NSString    *fullPath               = [databasePath stringByAppendingPathComponent:fileName];

[[NSFileManager defaultManager] createFileAtPath:fullPath contents:nil attributes:nil]; 

[databasePath release];
//[fileName release]; Error!
//[fullPath release]; Error!

//NSLog(@"#1 :databasePath: %d",[databasePath retainCount]);
//NSLog(@"#1 :fileName: %d",[fileName retainCount]);
//NSLog(@"#1 :fullPath: %d",[fullPath retainCount]);

I’m using this code and want to release NSString* ..
so, I declare fileName, fullPath, and databasePath of NSString.
database is released but fileName, fullpath doesn’t release. I don’t know why it happens.

I know that NSArray is Autoreleased. But is documentsDirectory autoreleased?
(newWordbookName is nsstring type)

I hope that I look through a document about iPhone memory management.

Answer 1

By convention the only two cases when a method returns a retained object are constructors i.e. alloc, new etc. and object-copying methods (containing copy in their name).

In all other cases the object is expected to be autoreleased, unless explicitly stated otherwise in the documentation.

This is the complete memory management documentation:
Cocoa Memory Management