Replacement for stringByAddingPercentEscapesUsingEncoding in ios9?

Question

In iOS8 and prior I can use:

NSString *str = ...; // some URL
NSString *result = [str stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

in iOS9 stringByAddingPercentEscapesUsingEncoding has been replaced with stringByAddingPercentEncodingWithAllowedCharacters:

NSString *str = ...; // some URL
NSCharacterSet *set = ???; // where to find set for NSUTF8StringEncoding?
NSString *result = [str stringByAddingPercentEncodingWithAllowedCharacters:set];

and my question is: where to find needed NSCharacterSet (NSUTF8StringEncoding) for proper replacement of stringByAddingPercentEscapesUsingEncoding?

Antonio Favata · Accepted Answer · 2016-09-27T23:38:04.247

134

The deprecation message says (emphasis mine):

Use stringByAddingPercentEncodingWithAllowedCharacters(_:) instead, which always uses the recommended UTF-8 encoding, and which encodes for a specific URL component or subcomponent since each URL component or subcomponent has different rules for what characters are valid.

So you only need to supply an adequate NSCharacterSet as argument. Luckily, for URLs there's a very handy class method called URLHostAllowedCharacterSet that you can use like this:

let encodedHost = unencodedHost.stringByAddingPercentEncodingWithAllowedCharacters(.URLHostAllowedCharacterSet())

Update for Swift 3 -- the method becomes the static property urlHostAllowed:

let encodedHost = unencodedHost.addingPercentEncoding(withAllowedCharacters: .urlHostAllowed)

Be aware, though, that:

This method is intended to percent-encode an URL component or subcomponent string, NOT an entire URL string.

edited Sep 27 '16 at 23:38

answered Sep 02 '15 at 10:13

Antonio Favata

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6

Also, I would strongly suggest using `NSURLComponents`, which can handle percent-encoding for you. – Antonio Favata Sep 02 '15 at 10:40
1

Any suggestions for what to use for the entire URL string? – ajeetdl Sep 20 '15 at 22:26
1

@SkillM2 I think `NSURLComponents` (with each component percent-encoded with the corresponding `NSCharacterSet`) is the right way to go. – Antonio Favata Sep 30 '15 at 11:34
2

You should never, ever, never attempt to encode an entire URL string. It can cause unexpected bugs, and in some cases, security holes. The only guaranteed correct way to encode a URL is to do it one piece at a time. – dgatwood May 08 '16 at 05:41
how do you do this for swift 3? – Joseph Astrahan Sep 27 '16 at 08:08
@JosephAstrahan In Swift 3 it becomes `let encodedHost = unencodedHost.addingPercentEncoding(withAllowedCharacters: .urlHostAllowed)` – Antonio Favata Sep 27 '16 at 14:37

ChenYilong · Answer 2 · 2016-03-10T12:22:38.050

For Objective-C：

NSString *str = ...; // some URL
NSCharacterSet *set = [NSCharacterSet URLHostAllowedCharacterSet]; 
NSString *result = [str stringByAddingPercentEncodingWithAllowedCharacters:set];

where to find set for NSUTF8StringEncoding?

There are predefined character sets for the six URL components and subcomponents which allow percent encoding. These character sets are passed to -stringByAddingPercentEncodingWithAllowedCharacters: .

 // Predefined character sets for the six URL components and subcomponents which allow percent encoding. These character sets are passed to -stringByAddingPercentEncodingWithAllowedCharacters:.
@interface NSCharacterSet (NSURLUtilities)
+ (NSCharacterSet *)URLUserAllowedCharacterSet;
+ (NSCharacterSet *)URLPasswordAllowedCharacterSet;
+ (NSCharacterSet *)URLHostAllowedCharacterSet;
+ (NSCharacterSet *)URLPathAllowedCharacterSet;
+ (NSCharacterSet *)URLQueryAllowedCharacterSet;
+ (NSCharacterSet *)URLFragmentAllowedCharacterSet;
@end

The deprecation message says (emphasis mine):

Use stringByAddingPercentEncodingWithAllowedCharacters(_:) instead, which always uses the recommended UTF-8 encoding, and which encodes for a specific URL component or subcomponent since each URL component or subcomponent has different rules for what characters are valid.

So you only need to supply an adequate NSCharacterSet as argument. Luckily, for URLs there's a very handy class method called URLHostAllowedCharacterSet that you can use like this:

NSCharacterSet *set = [NSCharacterSet URLHostAllowedCharacterSet];

Be aware, though, that:

This method is intended to percent-encode an URL component or subcomponent string, NOT an entire URL string.

What is the meaning of "This method is intended to percent-encode an URL component or subcomponent string, NOT an entire URL string." ? — GeneCode, Sep 01 '16 at 08:30
URLHostAllowedCharacterSet was giving error "Unsupported URL", I used URLFragmentAllowedCharacterSet and its working fine. — anoop4real, Sep 15 '16 at 11:52
this does not work with + it will not encode it and it will be replaced by space on server side as by specification. — Torge, May 03 '17 at 11:52

Lal Krishna · Answer 3 · 2018-01-18T09:16:45.677

51

URLHostAllowedCharacterSet is NOT WORKING FOR ME. I use URLFragmentAllowedCharacterSet instead.

OBJECTIVE -C

NSCharacterSet *set = [NSCharacterSet URLFragmentAllowedCharacterSet];
NSString * encodedString = [@"url string" stringByAddingPercentEncodingWithAllowedCharacters:set];

SWIFT - 4

"url string".addingPercentEncoding(withAllowedCharacters: .urlHostAllowed)

The following are useful (inverted) character sets:

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

edited Jan 18 '18 at 09:16

answered Jun 20 '17 at 04:33

Lal Krishna

15,485
6
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Thanks and same to you also – Arpit B Parekh Sep 14 '17 at 05:16
Worth noticing that none of these sets include `+`. So plus signs in the string will be messed up if passed on in query parameters - treated as space ` ` on the server side. – Asmo Soinio Feb 06 '20 at 07:35
Actually, the `+` sign will be encoded to `%2B`. So no worries. It will work. @AsmoSoinio – Lal Krishna Dec 08 '20 at 04:44

score 22 · Answer 4 · answered Mar 03 '17 at 16:34

22

Objective-C

this code work for me :

urlString = [urlString stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLFragmentAllowedCharacterSet]];

answered Mar 03 '17 at 16:34

Bilal L

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score 4 · Answer 5 · answered Mar 21 '16 at 19:44

Swift 2.2:

extension String {
 func encodeUTF8() -> String? {
//If I can create an NSURL out of the string nothing is wrong with it
if let _ = NSURL(string: self) {

    return self
}

//Get the last component from the string this will return subSequence
let optionalLastComponent = self.characters.split { $0 == "/" }.last


if let lastComponent = optionalLastComponent {

    //Get the string from the sub sequence by mapping the characters to [String] then reduce the array to String
    let lastComponentAsString = lastComponent.map { String($0) }.reduce("", combine: +)


    //Get the range of the last component
    if let rangeOfLastComponent = self.rangeOfString(lastComponentAsString) {
        //Get the string without its last component
        let stringWithoutLastComponent = self.substringToIndex(rangeOfLastComponent.startIndex)


        //Encode the last component
        if let lastComponentEncoded = lastComponentAsString.stringByAddingPercentEncodingWithAllowedCharacters(NSCharacterSet.alphanumericCharacterSet()) {


        //Finally append the original string (without its last component) to the encoded part (encoded last component)
        let encodedString = stringWithoutLastComponent + lastComponentEncoded

            //Return the string (original string/encoded string)
            return encodedString
        }
    }
}

return nil;
}
}

score 2 · Answer 6 · answered Oct 21 '16 at 06:21

For Swift 3.0

You can use urlHostAllowed characterSet.

/// Returns the character set for characters allowed in a host URL subcomponent.

public static var urlHostAllowed: CharacterSet { get }

WebserviceCalls.getParamValueStringForURLFromDictionary(settingsDict as! Dictionary<String, AnyObject>).addingPercentEncoding(withAllowedCharacters: CharacterSet.urlHostAllowed)

score 1 · Answer 7 · edited Jun 08 '17 at 08:59

What is the meaning of "This method is intended to percent-encode an URL component or subcomponent string, NOT an entire URL string." ? – GeneCode Sep 1 '16 at 8:30

It means that you are not supposed to encode the https://xpto.example.com/path/subpath of the url, but only what goes after the ?.

Supposed, because there are use-cases for doing it in cases like:

https://example.com?redirectme=xxxxx

Where xxxxx is a fully encoded URL.

score 0 · Answer 8 · answered Oct 29 '18 at 07:04

Adding to the accepted answer. Taking into consideration this note

This method is intended to percent-encode an URL component or subcomponent string, NOT an entire URL string.

the whole URL should not be encoded:

let param = "=color:green|\(latitude),\(longitude)&\("zoom=13&size=\(width)x\(height)")&sensor=true&key=\(staticMapKey)".addingPercentEncoding(withAllowedCharacters: .urlHostAllowed) 
let url = "https://maps.google.com/maps/api/staticmap?markers" + param!

Replacement for stringByAddingPercentEscapesUsingEncoding in ios9?

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