Objective-C and Swift URL encoding

Question

I have a NSString like this   http   www    but I want to transform it to   http 3A 2F 2Fwww    How can I do this

User · Accepted Answer

To escape the characters you want is a little more work.

Example code

iOS7 and above:

NSString *unescaped = @"http://www";
NSString *escapedString = [unescaped stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLHostAllowedCharacterSet]];
NSLog(@"escapedString: %@", escapedString);

NSLog output:

escapedString: http%3A%2F%2Fwww

The following are useful URL encoding character sets:

URLFragmentAllowedCharacterSet  "#%<>[\]^`{|}
URLHostAllowedCharacterSet      "#%/<>?@\^`{|}
URLPasswordAllowedCharacterSet  "#%/:<>?@[\]^`{|}
URLPathAllowedCharacterSet      "#%;<>?[\]^`{|}
URLQueryAllowedCharacterSet     "#%<>[\]^`{|}
URLUserAllowedCharacterSet      "#%/:<>?@[\]^`

Creating a characterset combining all of the above:

NSCharacterSet *URLCombinedCharacterSet = [[NSCharacterSet characterSetWithCharactersInString:@" \"#%/:<>?@[\\]^`{|}"] invertedSet];

Creating a Base64

In the case of Base64 characterset:

NSCharacterSet *URLBase64CharacterSet = [[NSCharacterSet characterSetWithCharactersInString:@"/+=\n"] invertedSet];

For Swift 3.0:

var escapedString = originalString.addingPercentEncoding(withAllowedCharacters:.urlHostAllowed)

For Swift 2.x:

var escapedString = originalString.stringByAddingPercentEncodingWithAllowedCharacters(NSCharacterSet.URLHostAllowedCharacterSet())

Note: stringByAddingPercentEncodingWithAllowedCharacters will also encode UTF-8 characters needing encoding.

Pre iOS7 use Core Foundation
Using Core Foundation With ARC:

NSString *escapedString = (NSString *)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(
    NULL,
   (__bridge CFStringRef) unescaped,
    NULL,
    CFSTR("!*'();:@&=+$,/?%#[]\" "),
    kCFStringEncodingUTF8));

Using Core Foundation Without ARC:

NSString *escapedString = (NSString *)CFURLCreateStringByAddingPercentEscapes(
    NULL,
   (CFStringRef)unescaped,
    NULL,
    CFSTR("!*'();:@&=+$,/?%#[]\" "),
    kCFStringEncodingUTF8);

Note: -stringByAddingPercentEscapesUsingEncoding will not produce the correct encoding, in this case it will not encode anything returning the same string.

stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding encodes 14 characrters:

`#%^{}[]|\"<> plus the space character as percent escaped.

testString:

" `~!@#$%^&*()_+-={}[]|\\:;\"'<,>.?/AZaz"

encodedString:

"%20%60~!@%23$%25%5E&*()_+-=%7B%7D%5B%5D%7C%5C:;%22'%3C,%3E.?/AZaz"

Note: consider if this set of characters meet your needs, if not change them as needed.

RFC 3986 characters requiring encoding (% added since it is the encoding prefix character):

"!#$&'()*+,/:;=?@[]%"

Some "unreserved characters" are additionally encoded:

"\n\r \"%-.<>\^_`{|}~"

User · Answer

This can work in Objective C ARC Use CFBridgingRelease to cast a Core Foundation-style object as an Objective-C object and transfer ownership of the object to ARC  See Function CFBridgingRelease here      NSString   encodeUrlString  NSString   string   return CFBridgingRelease CFURLCreateStringByAddingPercentEscapes                           kCFAllocatorDefault                               bridge CFStringRef string                            NULL                            CFSTR           amp                                         kCFStringEncodingUTF8

User · Answer

Swift iOS   Just For Information   I have used this   extension String        func urlEncode   - gt  CFString           return CFURLCreateStringByAddingPercentEscapes              nil              self              nil                        amp                          CFStringBuiltInEncodings UTF8 rawValue                      end extension String

User · Answer

It s called URL encoding   More here   - NSString   urlEncodeUsingEncoding  NSStringEncoding encoding       return  NSString   CFURLCreateStringByAddingPercentEscapes NULL              CFStringRef self             NULL              CFStringRef              amp                           CFStringConvertNSStringEncodingToEncoding encoding

User · Answer

use NSString instance method like this      NSString   encodeURIComponent  NSString   string   NSString  s    string stringByAddingPercentEscapesUsingEncoding NSUTF8StringEncoding   return s        NSString   decodeURIComponent  NSString   string   NSString  s    string stringByReplacingPercentEscapesUsingEncoding NSUTF8StringEncoding   return s      remember you should only do encode or decode for your parameter value  not all the url you request

User · Answer

NSString  str    NSString   CFURLCreateStringByAddingPercentEscapes                               NULL                                CFStringRef yourString                                NULL                                CFSTR                                      kCFStringEncodingUTF8     You will need to release or autorelease str yourself

User · Answer

NSString   encodedString    NSString   CFURLCreateStringByAddingPercentEscapes NUL  CFStringRef   parameter  NULL  CFStringRef           amp             -    kCFStringEncodingUTF8     NSURL   url     NSURL alloc  initWithString    address here  stringByAppendingFormat    cid     encodedString  nil

User · Answer

Here s what I use  Note you have to use the  autoreleasepool feature or the program might crash or lockup the IDE  I had to restart my IDE three times until I realized the fix  It appears that this code is ARC compliant   This question has been asked many times  and many answers given  but sadly all of the ones selected  and a few others suggested  are wrong   Here s the test string that I used  This is my 123  test  amp  test2  Got it    These are my Objective C   class methods   static NSString   urlDecode NSString  stringToDecode        NSString  result    stringToDecode stringByReplacingOccurrencesOfString      withString            result    result stringByReplacingPercentEscapesUsingEncoding NSUTF8StringEncoding       return result     static NSString   urlEncode NSString  stringToEncode         autoreleasepool           NSString  result    NSString   CFBridgingRelease CFURLCreateStringByAddingPercentEscapes                  NULL                   CFStringRef stringToEncode                  NULL                   CFStringRef              amp                                kCFStringEncodingUTF8                         result    result stringByReplacingOccurrencesOfString    20  withString                return result

User · Answer

int strLength   0  NSString  urlStr     http   www   NSLog    urlStr        urlStr    NSMutableString  mutableUrlStr    urlStr mutableCopy   NSLog    mutableUrlStr        mutableUrlStr    strLength    mutableUrlStr length    mutableUrlStr replaceOccurrencesOfString      withString    3A  options NSCaseInsensitiveSearch range NSMakeRange 0  strLength    NSLog    mutableUrlStr        mutableUrlStr    strLength    mutableUrlStr length    mutableUrlStr replaceOccurrencesOfString      withString    2F  options NSCaseInsensitiveSearch range NSMakeRange 0  strLength    NSLog    mutableUrlStr        mutableUrlStr

User · Answer

Google implements this in their Google Toolbox for Mac  So that s a good place to peak how they re doing it  Another option is to include the Toolbox and use their implementation    Checkout the implementation here   Which comes down to exactly what people have been posting here

User · Answer

This is how I am doing this in swift   extension String       func encodeURIComponent   - gt  String           return self stringByAddingPercentEncodingWithAllowedCharacters NSCharacterSet URLQueryAllowedCharacterSet                func decodeURIComponent   - gt  String           return self componentsSeparatedByString      joinWithSeparator      stringByRemovingPercentEncoding

User · Answer

This is not my solution  Someone else wrote in stackoverflow but I have forgotten how   Somehow this solution works  well   It handles diacritic  chinese characters  and pretty much anything else   -  NSString    URLEncodedString       NSMutableString   output    NSMutableString string       const char   source    self UTF8String       int sourceLen   strlen source       for  int i   0  i  lt  sourceLen    i            const unsigned char thisChar    const unsigned char source i           if  false  amp  amp  thisChar                       output appendString                  else if  thisChar           thisChar     -     thisChar           thisChar                               thisChar  gt    a   amp  amp  thisChar  lt    z                          thisChar  gt    A   amp  amp  thisChar  lt    Z                          thisChar  gt    0   amp  amp  thisChar  lt    9                   output appendFormat    c   thisChar             else                output appendFormat      02X   thisChar                       return output      If someone would tell me who wrote this code  I ll really appreciate it  Basically he has some explanation why this encoded string will decode exactly as it wish   I modified his solution a little  I like space to be represented with  20 rather than    That s all

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