Best way to parse URL string to get values for keys?

Question

I need to parse a URL string like this one:

&ad_eurl=http://www.youtube.com/video/4bL4FI1Gz6s&hl=it_IT&iv_logging_level=3&ad_flags=0&ends         


        

Answer 1

Since iOS 8 you can directly use properties name and value on NSURLQueryItem.

Example, how to parse URL and get specific values for a key in parsed pairs.

NSURLComponents *urlComponents = [NSURLComponents componentsWithURL:@"someURL" resolvingAgainstBaseURL:false];
NSArray *queryItems = urlComponents.queryItems;
NSMutableArray *someIDs = [NSMutableArray new];
for (NSURLQueryItem *item in queryItems) {
    if ([item.name isEqualToString:@"someKey"]) {
        [someIDs addObject:item.value];
    }
}
NSLog(@"%@", someIDs);

Answer 2

To get query parameters as a dict:

extension URL {
    var parameters: [String: String] {
        var parameters = [String: String]()
        if let urlComponents = URLComponents(url: self, resolvingAgainstBaseURL: false),
            let queryItems = urlComponents.queryItems {
            for queryItem in queryItems where queryItem.value != nil {
                parameters[queryItem.name] = queryItem.value
            }
        }
        return parameters
    }
}

or return Optional if this more convenient in your case.

Answer 3

I also answered this at https://stackoverflow.com/a/26406478/215748.

You can use queryItems in URLComponents.

When you get this property’s value, the NSURLComponents class parses the query string and returns an array of NSURLQueryItem objects, each of which represents a single key-value pair, in the order in which they appear in the original query string.

let url = "http://example.com?param1=value1&param2=param2"
let queryItems = URLComponents(string: url)?.queryItems
let param1 = queryItems?.filter({$0.name == "param1"}).first
print(param1?.value)

Alternatively, you can add an extension on URL to make things easier.

extension URL {
    var queryParameters: QueryParameters { return QueryParameters(url: self) }
}

class QueryParameters {
    let queryItems: [URLQueryItem]
    init(url: URL?) {
        queryItems = URLComponents(string: url?.absoluteString ?? "")?.queryItems ?? []
        print(queryItems)
    }
    subscript(name: String) -> String? {
        return queryItems.first(where: { $0.name == name })?.value
    }
}

You can then access the parameter by its name.

let url = URL(string: "http://example.com?param1=value1&param2=param2")!
print(url.queryParameters["param1"])

Answer 4

A Swift 2 approach:

extension NSURL {

  var queryDictionary: [String: String] {
    var queryDictionary = [String: String]()
    guard let components = NSURLComponents(URL: self, resolvingAgainstBaseURL: false), queryItems = components.queryItems else { return queryDictionary }
    queryItems.forEach { queryDictionary[$0.name] = $0.value }
    return queryDictionary
  }

}

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