Adding objects to an NSmutableArray from a C Array

Question

I have an NSmutable array and I am adding some strings present in the C array to it. By using this method

if (!self.arrayOfVariableNames) {
        self.arrayOfVariableNames = [[NSMutableArray alloc] init];
        for (int i = 0; i< cols; i++) {
            [self.arrayOfVariableNames addObject:[NSString stringWithCString:cArrayOfVariableNames[i] encoding:NSUTF8StringEncoding ]];
        }
    }
    else{
        [self.arrayOfVariableNames removeAllObjects];
        for (int i = 0; i< cols; i++) {
        [self.arrayOfVariableNames addObject:[NSString stringWithCString:cArrayOfVariableNames[i] encoding:NSUTF8StringEncoding ]];
        }
    }   

Does this method ensure that the objects in the NSmutableArray won't be deallocated when the C array is taken out of memory?

Answer 1

if this array arrayOfVariableNames is becoming Null, then the problem is with the initialisation of the array. Please try to use Lazy loading by doing this:

- (NSArray*)arrayOfVariableNames {
    if (!_arrayOfVariableNames) {
        _arrayOfVariableNames = [[NSMutableArray alloc] init];  //initialise the array if needed
    }
    return _arrayOfVariableNames;  //else return the already initialized array
}

and please comment out this line in your code: self.arrayOfVariableNames = [[NSMutableArray alloc] init];

****EDIT****
Please find the update code in https://docs.google.com/file/d/0BybTW7Dwp2_vdHhQN1p1UzExdTA/edit?pli=1. Have a look at it.

Answer 2

Yes. NSArray retains anything in it. But you should stop chaining your NSString creation and instead creat a string a line before adding it to the array. Then check for nil. Only add it to the array if it is not nil. Do code defensively.

Answer 3

arrayOfVariableNames will not change when the C array get deallocated.

Make sure that your arrayOfVariableNames variable is strong.

@property (nonatomic, strong) NSMutableArray *arrayOfVariableNames;

    if (!self.arrayOfVariableNames) 
    {
      self.arrayOfVariableNames = [[NSMutableArray alloc] init];
    }
    else
    {
      [self.arrayOfVariableNames removeAllObjects];
    }

   for (int i = 0; i< cols; i++) 
   {
       NSString *tempString = [NSString stringWithCString:cArrayOfVariableNames[i] encoding:NSUTF8StringEncoding];

       if([tempString length] > 0)
       {
         [self.arrayOfVariableNames addObject:tempString];
       }
       else
       {
         NSLog(@"string is empty");
       }
   }