NSString componentsSeparatedByString "&" but ignore "& amp;" - ios

Question

Need to separate a string on & but not on &.
Is there a more elegant way to code this up rather than just replacing it first then separating it on the &? Like this...
query = [query stringByReplacingOccurrencesOfString:#"&" withString:#"~~~"];
NSArray * kvpairs = [query componentsSeparatedByString:#"&"];
NSMutableArray *mArr = [[NSMutableArray alloc] init];
for (NSString *kvp in kvpairs) {
[mArr addObject:[kvp stringByReplacingOccurrencesOfString:#"~~~" withString:#"&"]];
}
kvpairs = [NSArray arrayWithArray:mArr];
[mArr release];

Answer 1

You could use NSRegularExpression to enumerate through the string on a regular expression that matches & but not &, e.g.: #"&(?!amp;)". This will be more cumbersome than your current method but more exact, because it will work without modifying the original string and doesn't rely on a token value.
If you control the input to this method and can guarantee that ~~~ won't appear normally, there's nothing wrong with using ~~~. However if you don't control the input then you should attempt to parse the string without modification.

Answer 2

There isn't really anything wrong with that, as long as you are 100% sure that the string ~~~ won't occur in your query.
If you are not, my next step would be to implement a method to parse the string into an array. In this method, you could find each &, then check if it is followed by amp;. If it is, move on to the next one, if it is not, cut the string there and repeat.

Answer 3

HTML entities and references are really not a good thing to have hanging around in URLs. Unless there is a very good reason that HTML entities must be used, I would recommend using '%26' in the URL encode an ampersand.
That being said, you will run into problems if '&' is not the only HTML entity or reference, so unless you are absolutely sure '&' is the only one, you will need a more robust solution.