Objective-C: How to add query parameter to NSURL?

Question

Let's say I have an NSURL? Whether or not it already has an empty query string, how do I add one or more parameters to the query of the NSURL? I.e., does anyone know of an implementation of this function?

- (NSURL *)URLByAppendingQueryString:(NSString *)queryString 

So that it satisfies this NSURL+AdditionsSpec.h file:

#import "NSURL+Additions.h" #import "Kiwi.h"  SPEC_BEGIN(NSURL_AdditionsSpec)  describe(@"NSURL+Additions", ^{     __block NSURL *aURL;      beforeEach(^{         aURL = [[NSURL alloc] initWithString:@"http://www.example.com"];         aURLWithQuery = [[NSURL alloc] initWithString:@"http://www.example.com?key=value"];     });      afterEach(^{         [aURL release];         [aURLWithQuery release];     });      describe(@"-URLByAppendingQueryString:", ^{         it(@"adds to plain URL", ^{             [[[[aURL URLByAppendingQueryString:@"key=value&key2=value2"] query] should]              equal:@"key=value&key2=value2"];         });          it(@"appends to the existing query sting", ^{             [[[[aURLWithQuery URLByAppendingQueryString:@"key2=value2&key3=value3"] query] should]              equal:@"key=value&key2=value2&key3=value3"];         });     }); });  SPEC_END 

Answer 1

Since iOS 7 you can use NSURLComponents that is very simple to use. Take a look on these examples:

Example 1

NSString *urlString = @"https://mail.google.com/mail/u/0/?shva=1#inbox"; NSURLComponents *components = [[NSURLComponents alloc] initWithString:urlString];  NSLog(@"%@ - %@ - %@ - %@", components.scheme, components.host, components.query, components.fragment); 

Example 2

NSString *urlString = @"https://mail.google.com/mail/u/0/?shva=1#inbox"; NSURLComponents *components = [[NSURLComponents alloc] initWithString:urlString];  if (components) {     //good URL } else {     //bad URL } 

Example 3

NSURLComponents *components = [NSURLComponents new]; [components setScheme:@"https"]; [components setHost:@"mail.google.com"]; [components setQuery:@"shva=1"]; [components setFragment:@"inbox"]; [components setPath:@"/mail/u/0/"];  [self.webview loadRequest:[[NSURLRequest alloc] initWithURL:[components URL]]]; 

But you can do many other things with NSURLComponents take a look on NSURLComponents class reference on Apple documentation or on this link: http://nshipster.com/nsurl/

Answer 2

Here's an implementation that passes your specs:

@implementation NSURL (Additions)  - (NSURL *)URLByAppendingQueryString:(NSString *)queryString {     if (![queryString length]) {         return self;     }      NSString *URLString = [[NSString alloc] initWithFormat:@"%@%@%@", [self absoluteString],                            [self query] ? @"&" : @"?", queryString];     NSURL *theURL = [NSURL URLWithString:URLString];     [URLString release];     return theURL; }  @end 

And here is an implementation for NSString:

@implementation NSString (Additions)  - (NSURL *)URLByAppendingQueryString:(NSString *)queryString {     if (![queryString length]) {         return [NSURL URLWithString:self];     }      NSString *URLString = [[NSString alloc] initWithFormat:@"%@%@%@", self,                            [self rangeOfString:@"?"].length > 0 ? @"&" : @"?", queryString];     NSURL *theURL = [NSURL URLWithString:URLString];     [URLString release];     return theURL; }  // Or:  - (NSString *)URLStringByAppendingQueryString:(NSString *)queryString {     if (![queryString length]) {         return self;     }     return [NSString stringWithFormat:@"%@%@%@", self,             [self rangeOfString:@"?"].length > 0 ? @"&" : @"?", queryString]; }  @end