How to Convert NSInteger to a binary (string) value

Question

I am trying to figure out how to convert an NSInteger, say 56, to an NSString that is a binary representation of the original (int) value. Perhaps someone knows a formatting technique that can accept 56 and return "111000" within Objective C. Thanks All.

Answer 1

There's no built-in formatting operator to do that. If you wanted to convert it to a hexadecimal string, you could do:

NSString *str = [NSString stringWithFormat:"%x", theNumber];

To convert it to a binary string, you'll have to build it yourself:

NSMutableString *str = @"";
for(NSInteger numberCopy = theNumber; numberCopy > 0; numberCopy >>= 1)
{
    // Prepend "0" or "1", depending on the bit
    [str insertString:((numberCopy & 1) ? @"1" : @"0") atIndex:0];
}

Answer 2

Roughly:

-(void)someFunction
{
  NSLog([self toBinary:input]);
}

-(NSString *)toBinary:(NSInteger)input
{
  if (input == 1 || input == 0)
    return [NSString stringWithFormat:@"%d", input];
  [NSString stringWithFormat:@"%@%d", [self toBinary:input / 2], input % 2];
}