How do I parse a NSString? - ios

Question

I have a string
https://gdata.youtube.com/feeds/api/videos?q=4s-PbMuNooo
I want to get string 4s-PbMuNooo. How do I parse a NSString?

Answer 1

Short answer :
NSString *myString = #"https://gdata.youtube.com/feeds/api/videos?q=4s-PbMuNooo";
NSArray *components = [myString componentsSeparatedByString:#"="];
NSString *query = [components lastObject];
Problems :
1) What if the bit after the q= contains another =
2) What if the q= bit is missing?
A better answer is for you to read the documentation - there are lots of helper methods on NSString that will get you substrings. Look for rangeOfString to find out where the equals would be and subStringWithRange to get the bit you want.
EDIT: Thomas has raised a fair point about URL parsing - see his answer here

Answer 2

A slightly longer but more complete answer. Hope this helps:
NSURL *url = [NSURL URLWithString: #"https://gdata.youtube.com/feeds/api/videos?param1=yeah&param2="];
NSArray *listItems = [[url query] componentsSeparatedByString:#"&"];
NSMutableDictionary *keyValues = [NSMutableDictionary dictionaryWithCapacity:listItems.count];
for (NSString *item in listItems) {
NSArray *keyValue = [item componentsSeparatedByString:#"="];
NSAssert(keyValue.count == 2, #"Key value pair mismatch");
[keyValues setObject:[keyValue objectAtIndex:1] forKey:[keyValue objectAtIndex:0]];
}
NSLog(#"1: %#", [keyValues objectForKey:#"param1"]);
NSLog(#"2: %#", [keyValues objectForKey:#"param2"]);

Answer 3

Like this:
NSArray *listItems = [yourString componentsSeparatedByString:#"="];
NSString *myFinalString=[NSString stringWithString:[listItems objectAtIndex:1]];

Answer 4

I wanted to try this a bit, so here is my code that handles more than one parameters:
NSURL *url = [NSURL URLWithString:#"https://gdata.youtube.com/feeds/api/videos?p=123123&q=234"];
NSArray *queryArray = [[url query] componentsSeparatedByString:#"&"];
for (NSString *queryString in queryArray) {
NSArray *queryComponents = [queryString componentsSeparatedByString:#"="];
if ([[queryComponents objectAtIndex:0] isEqualToString:#"q"]) {
NSLog(#"Found q: %#", [queryString substringFromIndex:2]);
} else {
NSLog(#"Did not find q.");
}
}

Answer 5

The question and its title are badly chosen - the answers are generally right for the more general task of splitting ANY string up, but bad for splitting up URLs as this question is actually about.
Here's how to properly get the values from a URL:
To break up a URL string, first do this:
NSURL *url = [NSURL URLWithString:urlString];
Then retrieve the parameters (the part past the "?") like this:
NSString *query = [url query];
Now you can go ahead and split that query string up using componentsSeparatedByString:#"&" as shown in the other answers.