TicTacToe board check - xcode

Question

I'm creating a TicTacToe game using command line in Xcode. I've got everything working properly except I can't figure out how to avoid a player from taking another players spot. So if player one chooses spot [1][1], if either player enters spot [1][1] throughout the game they will get "Invalid entry, please try again" and they will have to choose another spot. Any suggestions?
- (void) getChoice1
{
do
{
if (player == 1 && winner == 0 && turns < 9)
{
do {
//player 1's input
NSLog(#"Player 1, please choose a cell.");
NSLog(#"Enter row number(1, 2, or 3).");
scanf("%ld", &row);
} while ((row != 1 && row != 2 && row != 3));
do{
NSLog(#"Enter column number(1, 2, or 3).");
scanf("%ld", &column);
} while ((column != 1 && column != 2 && column != 3));
//decrement players input -1
row--;
column--;
//ensure spot is unselected
if (arr[row][column] == 1 || arr[row][column] == 2) {
NSLog(#"Invalid entry, try another spot");
[self getChoice1];
}
else
{
//add input to board
arr [row][column] = 1;
//display updated board
[self showBoard];
//switch players
player = 2;
//add a turn
turns++;
//check for winner
[self checkWinner];
}
}
} while (turns < 9 && winner == 0 );
}

Answer 1

You have to make userInteraction disabled for that block.
For example if block1 is touched, make :
block1.userInteractionEnabled = NO;
Once, game is complete, make userInteractionEnabled fro all blocks again to YES.
This will work as I have also made one similar game.
In case of command line , you can set some variables for example if for x set 1, for 0 set 2, for no play set 0.
Then, once someone new press there check for 1 and 2 and do the required

Answer 2

With the help of a friend I realized I have to restructure the method completely. Here's my working answer.
do
{
if (winner == 0 && turns < 9)
{
do {
//player 1's input
if (player == 1) {
NSLog(#"Player 1, please choose a cell.");
} else {
NSLog(#"Player 2, please choose a cell.");
}
NSLog(#"Enter row number(1, 2, or 3).");
scanf("%ld", &row);
} while ((row != 1 && row != 2 && row != 3));
do{
NSLog(#"Enter column number(1, 2, or 3).");
scanf("%ld", &column);
} while ((column != 1 && column != 2 && column != 3));
//decrement players input -1
row--;
column--;
//add input to board
if (arr [row][column] == 0) {
arr [row][column] = player;
if (player == 1) {
player = 2;
} else {
player = 1;
}
//display updated board
[self showBoard];
//add a turn
turns++;
} else {
NSLog (#"Cell already used pick a different cell.");
}
//check for winner
[self checkWinner];
}
} while (turns < 9 && winner == 0 );
}