Using NSString as an Array of NSStrings?

Question

I just came across a line of code that was written by a co-worker and I've never seen this before in Obj-C. It looks like poor form and I want to change it, but it seemingly works (the app is working as expected) and I don't even know what to change it to.

NSString **stringArray= new NSString *[numberOfStrings];

Is this OK? Would an NSArray of NSStrings make more sense?

EDIT: In order to properly free the array from memory, are any release calls needed? Currently, all I see is delete [] stringArray;.

EDIT 2: This seems to properly remove the array from memory:

for (int i=0; i < numberOfStrings; i++)
{
    [stringArray[i] release];
}
delete [] stringArray;

Let's say it's not the most beautiful solution I've seen. An NSArray of NSString makes much more sense in Objective C, and with an NSArray the code will play nicely with ARC too. — Joachim Isaksson
– Joachim Isaksson, Commented Jan 12, 2012 at 22:24
It it not Objective-C++, it's just a C-style array of NSString pointers. Nothing C++ about it. — Ben S
– Ben S, Commented Jan 12, 2012 at 22:25
@BenS What is this "new" in C or Objective-C? I must be behind the times... while the resulting type is the same, malloc/free and new/delete must be correctly paired. — user166390
– user166390, Commented Jan 12, 2012 at 22:27
This is a mix of C, C++ and Objective-C. You should ask your coworker what their reasoning was to write it like this. Some kind of strange guideline at your office, maybe? — Shaggy Frog
– Shaggy Frog, Commented Jan 12, 2012 at 22:34

Ben S · Accepted Answer · 2012-01-12 22:22:37Z

4

Using an NSArray might be more legible to someone without a C background, this is just a plain old C array filled with NSString*, perfectly valid but quite different from an NSArray instance.

Both make sense, but if the users of that array are expecting a C-style array rather than an NSArray instance, there might be a lot of refactoring involved.

answered Jan 12, 2012 at 22:22

Ben S

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Nikso · Accepted Answer · 2012-01-12 22:30:20Z

3

He is using Objective-C++ (you should be able to verify that in the 'file type' on the right panel for the file in xcode4).

the new keyword is creates a new array of (NSString *) with numberOfStrings size.

To answer your question, an NSArray would very likely be more manageable, especially if there are different developers on the code. To use a C++ array there may have been performance issues but that depends on the context of that code.

answered Jan 12, 2012 at 22:30

Nikso

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1 Comment

user166390 Over a year ago

+1 FWIW: The syntax here is: new T [count]: in this case T is NSString* so it's the same as new NSString* [numberOfStrings], which might be easier to "see", even though it has the * cuddling the braces in the post... let the style wars begin! ;-)

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