Is this the right way to create / destroy string in loop?

Question

Just curious if this is the way to do this, just want to make sure its not leaking, although I would think I am only modifying the string contents.

NSMutableString *newPath = [[NSMutableString alloc] init];

for(fileName in [manager enumeratorAtPath:rootPath]){
    if ([[fileName pathExtension] isEqual:@"exr"]) {
        [fileArray addObject:fileName];

        // THIS BIT 
        [newPath setString:rootPath];
        [newPath appendString:@"/"];
        [newPath appendString:fileName];
        // HERE
        attrDir = [manager attributesOfItemAtPath:newPath error:&myError];

        fileSize = [attrDir objectForKey: @"NSFileSize"];
        NSLog(@"File: /%@ Size: %@", fileName, fileSize);
    }
}
[newPath release];

gary

Answer 1

This looks fine leak-wise. If you're running Xcode 3.2 you can Build->Build & Analyzer to get Clang to check this sort of thing.

Remember you only have to release things you alloc, new, copy or retain.

Consider using stringByAppendingPathComponent, rather than hardcoding the @"/" path separator. NSString has a number of methods like this specifically for working with paths.

NSString* fullPath = [rootPath stringByAppendingPathComponent:fileName];

Answer 2

There's nothing wrong with it, although it could be better to use initWithFormat and release:

NSString *newPath = [[NSString alloc] initWithFormat:@"%@/%@",rootPath,fileName];

// do your thing

[newPath release];

Answer 3

There is absolutely nothing wrong with your code, it is correct memory management.

But it can be done with even less code and memory management needed:

for(fileName in [manager enumeratorAtPath:rootPath]){
  if ([[fileName pathExtension] isEqualToString:@"exr"]) {
    [fileArray addObject:fileName];

    NSString* newPath = [rootPath stringByAppendingPathComponent:fileName];
    attrDir = [manager attributesOfItemAtPath:newPath error:&myError];

    fileSize = [attrDir objectForKey: @"NSFileSize"];
    NSLog(@"File: /%@ Size: %@", fileName, fileSize);
  }
}