how to capture the required values from a URL - iphone

Question

I need to extract a variable's value from a string, which happens to be a URL. The string/url is loaded as part of a separate php query, not the url in the browser.
The url's will look like:
http://gmail.com?access_token=ab8w4azq2xv3dr4ab37vvzmh&token_type=bearer&expires_in=3600
How can I capture the value of the access_token which in this example is ab8w4azq2xv3dr4ab37vvzmh?

Answer 1

This code should do it:
- (NSString *)extractToken:(NSURL *)URL
{
NSString *urlString = [URL absoluteString];
NSRange start = [urlString rangeOfString:#"access_token="];
if (start.location != NSNotFound)
{
NSString *token = [urlString substringFromIndex:start.location+start.length];
NSRange end = [token rangeOfString:#"&"];
if (end.location != NSNotFound)
{
//trim off other parameters
token = [token substringToIndex:end.location];
}
return token;
}
//not found
return nil;
}
Alternatively, here is a more general solution that will extract all the query parameters into a dictionary:
- (NSDictionary *)URLQueryParameters:(NSURL *)URL
{
NSString *queryString = [URL query];
NSMutableDictionary *result = [NSMutableDictionary dictionary];
NSArray *parameters = [queryString componentsSeparatedByString:#"&"];
for (NSString *parameter in parameters)
{
NSArray *parts = [parameter componentsSeparatedByString:#"="];
NSString *key = [[parts objectAtIndex:0] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
if ([parts count] > 1)
{
id value = [[parts objectAtIndex:1] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
[result setObject:value forKey:key];
}
}
return result;
}

Answer 2

Good Category for NSDictionary:
#import "NSDictionary+URL.h"
#implementation NSDictionary (URL)
+ (NSDictionary *)dictionaryWithUrlString:(NSString *)urlString{
NSRange urlRange = [urlString rangeOfString:#"?"];
if(urlRange.length>0){
urlString = [urlString substringFromIndex:urlRange.length+urlRange.location];
}
NSArray *pairsArray = [urlString componentsSeparatedByString:#"&"];
NSMutableDictionary *parametersDictionary = [[NSMutableDictionary alloc] initWithCapacity:[pairsArray count]];
for(NSString *pairString in pairsArray){
NSArray *valuesArray = [pairString componentsSeparatedByString:#"="];
if([valuesArray count]==2){
[parametersDictionary setValue:[valuesArray objectAtIndex:1] forKey:[valuesArray objectAtIndex:0]];
}
}
return [parametersDictionary autorelease];
}
#end

Answer 3

NSMutableDictionary *querycomponent = [[NSMutableDictionary alloc] init];
if (![query isEqualToString:#""]){
NSArray *queryArray = [query componentsSeparatedByString:#"&"];
for (NSString *subquery in queryArray){
NSArray *subqueryArray = [subquery componentsSeparatedByString:#"="];
NSString *key = [subqueryArray objectAtIndex:0];
NSString *val = [subqueryArray objectAtIndex:1];
[querycomponent setObject:val forKey:key];
}
NSLog(#"querycomponent %#",querycomponent);
}