Parse NSURL query property

Question

I have a URL like myApp://action/1?parameter=2&secondparameter=3

With the property query I get following part of my URL

parameter=2&secondparameter=3

Is there any way easy to put this in a NSDictionary or an Array?

Thx a lot

Answer 1

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.

Swift

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

Answer 2

I had reason to write some extensions for this behavior that might come in handy. First the header:

#import <Foundation/Foundation.h>

@interface NSString (XQueryComponents)
- (NSString *)stringByDecodingURLFormat;
- (NSString *)stringByEncodingURLFormat;
- (NSMutableDictionary *)dictionaryFromQueryComponents;
@end

@interface NSURL (XQueryComponents)
- (NSMutableDictionary *)queryComponents;
@end

@interface NSDictionary (XQueryComponents)
- (NSString *)stringFromQueryComponents;
@end

These methods extend NSString, NSURL, and NSDictionary, to allow you to convert to and from query components strings and dictionary objects containing the results.

Now the related .m code:

#import "XQueryComponents.h"

@implementation NSString (XQueryComponents)
- (NSString *)stringByDecodingURLFormat
{
    NSString *result = [self stringByReplacingOccurrencesOfString:@"+" withString:@" "];
    result = [result stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    return result;
}

- (NSString *)stringByEncodingURLFormat
{
    NSString *result = [self stringByReplacingOccurrencesOfString:@" " withString:@"+"];
    result = [result stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    return result;
}

- (NSMutableDictionary *)dictionaryFromQueryComponents
{
    NSMutableDictionary *queryComponents = [NSMutableDictionary dictionary];
    for(NSString *keyValuePairString in [self componentsSeparatedByString:@"&"])
    {
        NSArray *keyValuePairArray = [keyValuePairString componentsSeparatedByString:@"="];
        if ([keyValuePairArray count] < 2) continue; // Verify that there is at least one key, and at least one value.  Ignore extra = signs
        NSString *key = [[keyValuePairArray objectAtIndex:0] stringByDecodingURLFormat];
        NSString *value = [[keyValuePairArray objectAtIndex:1] stringByDecodingURLFormat];
        NSMutableArray *results = [queryComponents objectForKey:key]; // URL spec says that multiple values are allowed per key
        if(!results) // First object
        {
            results = [NSMutableArray arrayWithCapacity:1];
            [queryComponents setObject:results forKey:key];
        }
        [results addObject:value];
    }
    return queryComponents;
}
@end

@implementation NSURL (XQueryComponents)
- (NSMutableDictionary *)queryComponents
{
    return [[self query] dictionaryFromQueryComponents];
}
@end

@implementation NSDictionary (XQueryComponents)
- (NSString *)stringFromQueryComponents
{
    NSString *result = nil;
    for(__strong NSString *key in [self allKeys])
    {
        key = [key stringByEncodingURLFormat];
        NSArray *allValues = [self objectForKey:key];
        if([allValues isKindOfClass:[NSArray class]])
            for(__strong NSString *value in allValues)
            {
                value = [[value description] stringByEncodingURLFormat];
                if(!result)
                    result = [NSString stringWithFormat:@"%@=%@",key,value];
                else 
                    result = [result stringByAppendingFormat:@"&%@=%@",key,value];
            }
        else {
            NSString *value = [[allValues description] stringByEncodingURLFormat];
            if(!result)
                result = [NSString stringWithFormat:@"%@=%@",key,value];
            else 
                result = [result stringByAppendingFormat:@"&%@=%@",key,value];
        }
    }
    return result;
}
@end

Answer 3

Something like that:

NSMutableDictionary *params = [[NSMutableDictionary alloc] init];
for (NSString *param in [url componentsSeparatedByString:@"&"]) {
  NSArray *elts = [param componentsSeparatedByString:@"="];
  if([elts count] < 2) continue;
  [params setObject:[elts lastObject] forKey:[elts firstObject]];
}

Note : This is sample code. All error cases are not managed.

Answer 4

Try this ;)!

NSString *query = @"parameter=2&secondparameter=3"; // replace this with [url query];
NSArray *components = [query componentsSeparatedByString:@"&"];
NSMutableDictionary *parameters = [[NSMutableDictionary alloc] init];
for (NSString *component in components) {
    NSArray *subcomponents = [component componentsSeparatedByString:@"="];
    [parameters setObject:[[subcomponents objectAtIndex:1] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding]
                   forKey:[[subcomponents objectAtIndex:0] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
}

Answer 5

All previous posts do not do the url encoding properly. I would suggest the following methods:

+(NSString*)concatenateQuery:(NSDictionary*)parameters {
    if([parameters count]==0) return nil;
    NSMutableString* query = [NSMutableString string];
    for(NSString* parameter in [parameters allKeys])
        [query appendFormat:@"&%@=%@",[parameter stringByAddingPercentEncodingWithAllowedCharacters:NSCharacterSet.URLQueryAllowedCharacterSet],[[parameters objectForKey:parameter] stringByAddingPercentEncodingWithAllowedCharacters:NSCharacterSet.URLQueryAllowedCharacterSet]];
    return [[query substringFromIndex:1] copy];
}
+(NSDictionary*)splitQuery:(NSString*)query {
    if([query length]==0) return nil;
    NSMutableDictionary* parameters = [NSMutableDictionary dictionary];
    for(NSString* parameter in [query componentsSeparatedByString:@"&"]) {
        NSRange range = [parameter rangeOfString:@"="];
        if(range.location!=NSNotFound)
            [parameters setObject:[[parameter substringFromIndex:range.location+range.length] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding] forKey:[[parameter substringToIndex:range.location] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
        else [parameters setObject:[[NSString alloc] init] forKey:[parameter stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
    }
    return [parameters copy];
}

Answer 6

According to the already very clean answer of Onato I wrote an extension for NSURL in Swift where you can get a query param like this:

e.g. the URL contains the pair param=some_value

let queryItem = url.queryItemForKey("param")
let value = queryItem.value // would get String "someValue"

The extension looks like:

extension NSURL {

  var allQueryItems: [NSURLQueryItem] {
      get {
          let components = NSURLComponents(URL: self, resolvingAgainstBaseURL: false)!
          let allQueryItems = components.queryItems!
          return allQueryItems as [NSURLQueryItem]
      }
  }

  func queryItemForKey(key: String) -> NSURLQueryItem? {

      let predicate = NSPredicate(format: "name=%@", key)!
      return (allQueryItems as NSArray).filteredArrayUsingPredicate(predicate).first as? NSURLQueryItem

  }
}

Answer 7

Here is the extension in swift:

extension NSURL{
        func queryParams() -> [String:AnyObject] {
            var info : [String:AnyObject] = [String:AnyObject]()
            if let queryString = self.query{
                for parameter in queryString.componentsSeparatedByString("&"){
                    let parts = parameter.componentsSeparatedByString("=")
                    if parts.count > 1{
                        let key = (parts[0] as String).stringByReplacingPercentEscapesUsingEncoding(NSUTF8StringEncoding)
                        let value = (parts[1] as String).stringByReplacingPercentEscapesUsingEncoding(NSUTF8StringEncoding)
                        if key != nil && value != nil{
                            info[key!] = value
                        }
                    }
                }
            }
            return info
        }
    }

Answer 8

The preferred way to deal with URLs is now NSURLComponents. In particular the queryItems property which returns an NSArray of params.

If you want the params in a NSDictionary, here's a method:

+(NSDictionary<NSString *, NSString *>*)queryParamsFromURL:(NSURL*)url
{
    NSURLComponents* urlComponents = [NSURLComponents componentsWithURL:url resolvingAgainstBaseURL:NO];

    NSMutableDictionary<NSString *, NSString *>* queryParams = [NSMutableDictionary<NSString *, NSString *> new];
    for (NSURLQueryItem* queryItem in [urlComponents queryItems])
    {
        if (queryItem.value == nil)
        {
            continue;
        }
        [queryParams setObject:queryItem.value forKey:queryItem.name];
    }
    return queryParams;
}

Caveat: URLs can have repeated params, but the dictionary will only contain the last value of any duplicated param. If that is undesirable, use the queryItems array directly.

Answer 9

For those using Bolts Framework you can use:

NSDictionary *parameters = [BFURL URLWithURL:yourURL].inputQueryParameters;

Remember to import:

#import <Bolts/BFURL.h>

If you happen to have Facebook SDK in your project, you also have Bolts. Facebook is using this framework as a dependency.

Answer 10

Swift 2.1

Oneliner:

"p1=v1&p2=v2".componentsSeparatedByString("&").map {
    $0.componentsSeparatedByString("=") 
}.reduce([:]) {
    (var dict: [String:String], p) in
    dict[p[0]] = p[1]
    return dict
}

// ["p1": "v1", "p2": "v2"]

Used as an extension on NSURL:

extension NSURL {

    /**
     * URL query string as dictionary. Empty dictionary if query string is nil.
     */
    public var queryValues : [String:String] {
        get {
            if let q = self.query {
                return q.componentsSeparatedByString("&").map {
                    $0.componentsSeparatedByString("=") 
                }.reduce([:]) {
                    (var dict: [String:String], p) in
                    dict[p[0]] = p[1]
                    return dict
                }
            } else {
                return [:]
            }
        }
    }

}

Example:

let url = NSURL(string: "http://example.com?p1=v1&p2=v2")!
let queryDict = url.queryValues

// ["p1": "v1", "p2": "v2"]

Please note, if using OS X 10.10 or iOS 8 (or later), it's probably better to use NSURLComponents and the queryItems property and create the dictionary from the NSURLQueryItems directly.

Here's a NSURLComponents based NSURL extension solution:

extension NSURL {

    /// URL query string as a dictionary. Empty dictionary if query string is nil.
    public var queryValues : [String:String] {
        get {
            guard let components = NSURLComponents(URL: self, resolvingAgainstBaseURL: false) else {
                return [:]
            }

            guard let queryItems = components.queryItems else {
                return [:]
            }

            var result:[String:String] = [:]
            for q in queryItems {
                result[q.name] = q.value
            }
            return result
        }
    }

}

A footnote to the NSURL extension is that it's actually possible in Swift to give the property the same name as the existing string property—query. I didn't know until I tried it, but the polymorphism in Swift lets you differ only on the return type. So if the extended NSURL property is public var query: [String:String] it works. I didn't use this in the example as I find it a little bit crazy, but it does work ...

Answer 11

I published a simple class doing the job under MIT:

https://github.com/anegmawad/URLQueryToCocoa

With it you can have arrays and objects in the query, which are collected and glued together

For Example

users[0][firstName]=Amin&users[0][lastName]=Negm&name=Devs&users[1][lastName]=Kienle&users[1][firstName]=Christian

will become:

@{
   name : @"Devs",
   users :
   @[
      @{
         firstName = @"Amin",
         lastName = @"Negm"
      },
      @{
         firstName = @"Christian",
         lastName = @"Kienle"
      }
   ]
 }

You can think of it as a URL query counterpart of NSJSONSerializer.

Answer 12

It looks that you are using it to process incoming data from another iOS application. If so, this is what I use for the same purpose.

Initial call (e.g. in external application):

UIApplication *application = [UIApplication sharedApplication];
NSURL *url = [NSURL URLWithString:@"myApp://action/1?parameter=2&secondparameter=3"];
if ([application canOpenURL:url]) {
    [application openURL:url];
    NSLog(@"myApp is installed");
} else {
    NSLog(@"myApp is not installed");
}

Method to extract QueryString data from NSURL and save as NSDictionary:

-(NSDictionary *) getNSDictionaryFromQueryString:(NSURL *)url {
   NSMutableDictionary *result = [[NSMutableDictionary alloc] init];
   NSRange needle = [url.absoluteString rangeOfString:@"?" options:NSCaseInsensitiveSearch];
   NSString *data = nil;

   if(needle.location != NSNotFound) {
       NSUInteger start = needle.location + 1;
       NSUInteger end = [url.absoluteString length] - start;
       data = [url.absoluteString substringWithRange:NSMakeRange(start, end)];
   }

   for (NSString *param in [data componentsSeparatedByString:@"&"]) {
       NSArray *keyvalue = [param componentsSeparatedByString:@"="];
       if([keyvalue count] == 2){
           [result setObject:[keyvalue objectAtIndex:1] forKey:[keyvalue objectAtIndex:0]];
       }
   }

  return result;
}

Usage:

NSDictionary *result = [self getNSDictionaryFromQueryString:url];

Answer 13

This class is a nice solution for url parsing.

.h file

@interface URLParser : NSObject {
    NSArray *variables;
}

@property (nonatomic, retain) NSArray *variables;

- (id)initWithURLString:(NSString *)url;
- (NSString *)valueForVariable:(NSString *)varName;

@end

.m file

#import "URLParser.h"

@implementation URLParser
@synthesize variables;

- (id) initWithURLString:(NSString *)url{
    self = [super init];
    if (self != nil) {
        NSString *string = url;
        NSScanner *scanner = [NSScanner scannerWithString:string];
        [scanner setCharactersToBeSkipped:[NSCharacterSet characterSetWithCharactersInString:@"&?"]];
        NSString *tempString;
        NSMutableArray *vars = [NSMutableArray new];
        [scanner scanUpToString:@"?" intoString:nil];       //ignore the beginning of the string and skip to the vars
        while ([scanner scanUpToString:@"&" intoString:&tempString]) {
            [vars addObject:[tempString copy]];
        }
        self.variables = vars;
    }
    return self;
}

- (NSString *)valueForVariable:(NSString *)varName {
    for (NSString *var in self.variables) {
        if ([var length] > [varName length]+1 && [[var substringWithRange:NSMakeRange(0, [varName length]+1)] isEqualToString:[varName stringByAppendingString:@"="]]) {
            NSString *varValue = [var substringFromIndex:[varName length]+1];
            return varValue;
        }
    }
    return nil;
}

@end

Answer 14

Hendrik wrote a nice example for extension in this question, however I had to re-write it to not use any objective-c library methods. Using NSArray in swift is not the correct approach.

This is the result, all swift and a bit more safe. The usage example will be less lines of code with Swift 1.2.

public extension NSURL {
    /*
    Set an array with all the query items
    */
    var allQueryItems: [NSURLQueryItem] {
        get {
            let components = NSURLComponents(URL: self, resolvingAgainstBaseURL: false)!
            if let allQueryItems = components.queryItems {
                return allQueryItems as [NSURLQueryItem]
            } else {
                return []
            }
        }
    }

    /**
    Get a query item form the URL query

    :param: key The parameter to fetch from the URL query

    :returns: `NSURLQueryItem` the query item
    */
    public func queryItemForKey(key: String) -> NSURLQueryItem? {
        let filteredArray = filter(allQueryItems) { $0.name == key }

        if filteredArray.count > 0 {
            return filteredArray.first
        } else {
            return nil
        }
    }
}

Usage:

let queryItem = url.queryItemForKey("myItem")

Or, more detailed usage:

if let url = NSURL(string: "http://www.domain.com/?myItem=something") {
    if let queryItem = url.queryItemForKey("myItem") {
        if let value = queryItem.value {
            println("The value of 'myItem' is: \(value)")
        }
    }
}

Answer 15

try this:

-(NSDictionary *)getUrlParameters:(NSString *)url{
    NSArray *justParamsArr = [url componentsSeparatedByString:@"?"];
    url = [justParamsArr lastObject];
    NSMutableDictionary *params = [[NSMutableDictionary alloc] init];
    for (NSString *param in [url componentsSeparatedByString:@"&"]) {
        NSArray *elts = [param componentsSeparatedByString:@"="];
        if([elts count] < 2) continue;
        [params setObject:[elts lastObject] forKey:[elts firstObject]];
    }
    return params;
}

Answer 16

Fairly compact approach:

    func stringParamsToDict(query: String) -> [String: String] {
        let params = query.components(separatedBy: "&").map {
            $0.components(separatedBy: "=")
        }.reduce(into: [String: String]()) { dict, pair in
            if pair.count == 2 {
                dict[pair[0]] = pair[1]
            }
        }
        return params
    }

Answer 17

Most robust solution if you are using a URL to pass data from the web app to the phone and you want to pass arrays, numbers, strings, ...

JSON encode your object in PHP

header("Location: myAppAction://".urlencode(json_encode($YOUROBJECT)));

And JSON decode the result in iOS

NSData *data = [[[request URL] host] dataUsingEncoding:NSUTF8StringEncoding];
NSDictionary *packed = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];