Replacement for stringByAddingPercentEscapesUsingEncoding in ios9?

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`?

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.

`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;
}
}

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.

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)

Objective-C

this code work for me :

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

> 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:

[To see links please register here]

?redirectme=xxxxx

Where `xxxxx` is a fully encoded URL.

`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 "#%/:<>?@[\]^`

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!