Convert a hash to NSString?

Question

Using the Evernote API, I have an object which has an NSUInteger property called hash. For the specific object I'm looking at, this is equal to:

<f5b5444b 33e740b7 f9d49a3b ddb6a39c>

I want to convert this into an NSString. Doing this:

[NSString stringWithFormat:@"%d", noteResource.hash]

Gives me this:

530049088

How could I correctly convert the hash value to an NSString?

Eeeeuuuughhhh... Are you using a 128-bit machine? Or how can an `NSInteger` occupy 16 bytes? — , Jul 11 '13 at 11:13
Do you want this : http://stackoverflow.com/q/7520615/1603072 ? — Bhavin, Jul 11 '13 at 11:15
@Vin It looks like it. The remaining problem is that it's an NSUInteger, what I have. How do I convert that to a `const void *`? — Andrew, Jul 11 '13 at 11:21
`noteResource` is an `NSData` object, and `noteResource.hash` is some hash value (NSUInteger). What do you mean by *"correctly convert the hash value to an NSString"*? Why convert to `const void *`? What result do you expect? — Martin R, Jul 11 '13 at 11:25

score 3 · Accepted Answer · answered Jul 11 '13 at 13:24

When you see something output as "<" 8 hex digits space .... ">", it's the result of logging a NSData object (NSLog(@"%@", myDataObject);). So I believe what you have is not an NSUInteger, but a NSData * object.

There is no built in method to convert between strings and data, you need to do it in code:

- (NSString *)dataToString:(NSData *)data
{
    NSUInteger len = [data length];
    NSMutableString *str = [NSMutableString stringWithCapacity:len*2];
    const uint8_t *bptr = [data bytes];

    while(len--) [str appendFormat:@"%02.2x", *bptr++];

    return str;
}

If this works, you can write your own stringToData method reversing the above, if needed.

Convert a hash to NSString?

1 Answers1