AppCode warning about a C-style array in an Objective-C class

Question

@implementation MonthView {
    DayView *dayViews[6][7];
}

Xcode does not complain about this code, but AppCode gives a warning:

Pointer to non-const type 'DayView * * const * ' with no explicit lifetime

My intention was to create a 6x7 block of DayView pointers that will be part of the memory layout of any MonthView instance.

Is this code doing what I want, and how can I fix this warning?

On the second line of the snippet, beginning with DayView... — titaniumdecoy, Dec 23 '11 at 23:38
The construct looks legitimate. My guess is that it's a bug in the AppCode. I tried a 2D array of `id` objects with `dealloc`, and verified that ARC handles them correctly. — Sergey Kalinichenko, Dec 24 '11 at 01:10
`NSArray` would be an improvement in most scenarios… I can't think of one instance of this form in my codebase (that still exists). — justin, Jan 06 '12 at 05:01
This is indeed a bug, please follow and vote for http://youtrack.jetbrains.com/issue/OC-3244 — Anton Makeev, Mar 09 '12 at 11:50
@AntonMakeev: Thanks for the verification. As your response is the correct answer, I would be happy to give you credit if you post it as an answer to this question. — titaniumdecoy, Mar 09 '12 at 18:30

Rabbit · Answer 1 · 2012-01-06T03:40:54.150

What you're attempting to do is valid, but if the comments above are correct and this is due to a bug in AppCode and the warning you receive throws a wrench into the works (such as when using -Werror) or it just bothers you to receive it, you can get around it by just allocating the array inside -init.

Fair warning: This code is off the top of my head and I don't guarantee it to work as written.

@implementation MonthView { 
     DayView ***dayViews;
}

@interface MonthView
     - (id)init {
          if ((self = [super init])) {
               int i;

               // do stuff here

               // Create the array
               dayViews = malloc(sizeof(id) * 6);
               dayViews[0] = malloc(sizeof(DayView *) * 6 * 7);

               for (i = 1; i < 6; i++) {
                    dayViews[i] = dayViews[0] + (i * 7);
               }
          }

          return self;
     }
@end

This code should produce a two-dimensional array that you can access as normal, while minimizing the number of calls to malloc needed.

AppCode warning about a C-style array in an Objective-C class

1 Answers1