SpiralMatrix

#import <Foundation/Foundation.h>

void printMatrix(NSMutableArray *dataArray, int size){
    NSMutableString *output = [[NSMutableString alloc] init];
    for (int i = 0; i < size; i++){
        for (int j = 0; j < size; j++){
            [output appendFormat:@"%4d", [dataArray[i][j] intValue]];
        }
        [output appendString:@"\n"];
    }
    NSLog(@"\n%@", output);
}

void fillMatrix(NSMutableArray *arrayMatrix, int size){
    int counter = 1;
    int y = 0;
    int x = 0;
    int newX = -1;
    int newY = 0;
    int direction = 1;
    while(counter <= size*size){
        switch(direction%4){
            case 0: newY--; break;
            case 1: newX++; break;
            case 2: newY++; break;
            case 3: newX--; break;
        }

        if(0 <= newX && newX < size && 0 <= newY && newY < size && [arrayMatrix[newY][newX] intValue] == 0){
            y = newY;
            x = newX;
            arrayMatrix[y][x] = [NSNumber numberWithInt: counter];
        } else{
            newX = x;
            newY = y;
            ++direction;
            continue;
        }
        ++counter;
    }
}

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        int size = 5;
        NSMutableArray *dataArray = [[NSMutableArray alloc] initWithCapacity: size];
        for(int i = 0; i < size; i++){
            NSMutableArray *row = [[NSMutableArray alloc] init];
            for(int j = 0; j < size; j++){
                [row addObject: @0];
            }
            [dataArray insertObject:row atIndex:i];
        }
        fillMatrix(dataArray,size);
        printMatrix(dataArray,size);
    }
    return 0;
}