How can I check for an empty object within an NSArray

Question

I'd like to check for an empty object (i.e. an object of an array which doesn't have a value) within an array which gets its data from a file.

As an example, if my array contains 12 objects (all NSString) and the object at index 11 doesn't return a value when its description is printed into the debug section of Xcode. I want to check if that is the case and respond accordingly. I already tried

if (!([MY_ARRAY objectAtIndex:11] == nil))
{
   //Some Stuff
}
else
{
  //Some other Stuff
}

which didn't work.

Any help is appreciated.

Answer 1

The description method is for debugging. You should not use it in your program logic. What are these objects, and what do they contain? Can you modify the objects to add an "isEmpty" property?

If you use NSNull, you'd use code like this:

NSArray *array = @{@"String", @(4), [NSNull null], @"Another string");

for (id anObject in array)
{
  if (anObject =! [NSNull null]))
  {
     //Some Stuff
  }
  else
  {
    //Some other Stuff
  }
}

Answer 2

You can check the length of the string: [string length] > 0

Answer 3

an object is an array cannot be nil, but you can use [NSNull null] which is an "object equivalent" to nil

Answer 4

As Jerome Diaz states, objects in an array can't be nil. The only option you have is to check the count property of the array if it reflects an expected value, or you can inspect the type/class of the object in the array. A safe way to include empty object into array is [NSNull null], but this is the task for the method that fills the array, not the one that reads it.

You can check the class type of an object in array with isKindOfClass or isMemberOfClass.