Every array in Objective-C is one-dimensional. To simulate a two-dimensional array, we create an array of arrays. The following app simulates a 4 × 3 array of strings with four rows and three columns. As usual, the numbers are zero-based.
objectAtIndex:id,
and any message
(in this case,
count)
can be sent without a cast
to an
id.
But the
count
property of an
id
would have required a cast.
I used
printf
instead of
NSLog
because
NSLog
always outputs a newline.
The first argument of
printf
must be a string without a
@.
Within this string,
printf
does not know about the
@%
format.
2011-12-08 13:12:03.942 Twod[58127:207] a.count == 4 2011-12-08 13:12:03.944 Twod[58127:207] [[a objectAtIndex: 0] count] == 3 2011-12-08 13:12:03.944 Twod[58127:207] [[a objectAtIndex: 1] count] == 3 2011-12-08 13:12:03.944 Twod[58127:207] [[a objectAtIndex: 2] count] == 3 2011-12-08 13:12:03.945 Twod[58127:207] [[a objectAtIndex: 3] count] == 3 (row 0, col 0) (row 0, col 1) (row 0, col 2) (row 1, col 0) (row 1, col 1) (row 1, col 2) (row 2, col 0) (row 2, col 1) (row 2, col 2) (row 3, col 0) (row 3, col 1) (row 3, col 2)