Find the highest repeated character

gistfile1.m

int array[255] = {0};
NSString *test = @"Test string.";
    
int i = 0;
for(i = 0; i < test.length; i++)
{
    ++array[[test characterAtIndex:i]];
}
    
int max = array[0];
int index = 0;
for(i = 0; i < 255; i++)
{
    if( array[i] > max)
    {
        max = array[i];
        index = i;
    }
}
    
NSLog(@"The highest repeated character is: %c", index);