如何对字符串进行URL编码？

Unfortunately, stringByAddingPercentEscapesUsingEncoding doesn't always work 100%. It encodes non-URL characters but leaves the reserved characters (like slash / and ampersand &) alone. Apparently this is a bug that Apple is aware of, but since they have not fixed it yet, I have been using this category to url-encode a string:

@implementation NSString (NSString_Extended)


- (NSString *)urlencode {
NSMutableString *output = [NSMutableString string];
const unsigned char *source = (const unsigned char *)[self UTF8String];
int sourceLen = strlen((const char *)source);
for (int i = 0; i < sourceLen; ++i) {
const unsigned char thisChar = source[i];
if (thisChar == ' '){
[output appendString:@"+"];
} else if (thisChar == '.' || thisChar == '-' || thisChar == '_' || thisChar == '~' ||
(thisChar >= 'a' && thisChar <= 'z') ||
(thisChar >= 'A' && thisChar <= 'Z') ||
(thisChar >= '0' && thisChar <= '9')) {
[output appendFormat:@"%c", thisChar];
} else {
[output appendFormat:@"%%%02X", thisChar];
}
}
return output;
}

Used like this:

NSString *urlEncodedString = [@"SOME_URL_GOES_HERE" urlencode];


// Or, with an already existing string:
NSString *someUrlString = @"someURL";
NSString *encodedUrlStr = [someUrlString urlencode];

This also works:

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

Some good reading about the subject:

Objective-c iPhone percent encode a string?
Objective-C and Swift URL encoding

http://cybersam.com/programming/proper-url-percent-encoding-in-ios
https://devforums.apple.com/message/15674#15674 http://simonwoodside.com/weblog/2009/4/22/how_to_really_url_encode/

I opted to use the CFURLCreateStringByAddingPercentEscapes call as given by accepted answer, however in newest version of XCode (and IOS), it resulted in an error, so used the following instead:

NSString *apiKeyRaw = @"79b|7Qd.jW=])(fv|M&W0O|3CENnrbNh4}2E|-)J*BCjCMrWy%dSfGs#A6N38Fo~";


NSString *apiKey = (NSString *)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(NULL, (CFStringRef)apiKeyRaw, NULL, (CFStringRef)@"!*'();:@&=+$,/?%#[]", kCFStringEncodingUTF8));

This might be helpful

NSString *sampleUrl = @"http://www.google.com/search.jsp?params=Java Developer";
NSString* encodedUrl = [sampleUrl stringByAddingPercentEscapesUsingEncoding:
NSUTF8StringEncoding];

For iOS 7+, the recommended way is:

NSString* encodedUrl = [sampleUrl stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];

You can choose the allowed character set as per the requirement of the URL component.

New APIs have been added since the answer was selected; You can now use NSURLUtilities. Since different parts of URLs allow different characters, use the applicable character set. The following example encodes for inclusion in the query string:

encodedString = [myString stringByAddingPercentEncodingWithAllowedCharacters:NSCharacterSet.URLQueryAllowedCharacterSet];

To specifically convert '&', you'll need to remove it from the url query set or use a different set, as '&' is allowed in a URL query:

NSMutableCharacterSet *chars = NSCharacterSet.URLQueryAllowedCharacterSet.mutableCopy;
[chars removeCharactersInRange:NSMakeRange('&', 1)]; // %26
encodedString = [myString stringByAddingPercentEncodingWithAllowedCharacters:chars];

swift code based on chown's objc answer in this thread.

extension String {
func urlEncode() -> String {
return CFURLCreateStringByAddingPercentEscapes(
nil,
self,
nil,
"!*'();:@&=+$,/?%#[]",
CFStringBuiltInEncodings.UTF8.rawValue
)
}
}

For individual www form-encoded query parameters, I made a category on NSString:

- (NSString*)WWWFormEncoded{
NSMutableCharacterSet *chars = NSCharacterSet.alphanumericCharacterSet.mutableCopy;
[chars addCharactersInString:@" "];
NSString* encodedString = [self stringByAddingPercentEncodingWithAllowedCharacters:chars];
encodedString = [encodedString stringByReplacingOccurrencesOfString:@" " withString:@"+"];
return encodedString;
}

ios 7 update

NSString *encode = [string stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];


NSString *decode = [encode stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

//This is without test

NSMutableCharacterSet* set = [[NSCharacterSet alphanumericCharacterSet] mutableCopy];
[set addCharactersInString:@"-_.~"];
NSString *encode = [test stringByAddingPercentEncodingWithAllowedCharacters:set];

Swift 2.0 Example (iOS 9 Compatiable)

extension String {


func stringByURLEncoding() -> String? {


let characters = NSCharacterSet.URLQueryAllowedCharacterSet().mutableCopy() as! NSMutableCharacterSet


characters.removeCharactersInString("&")


guard let encodedString = self.stringByAddingPercentEncodingWithAllowedCharacters(characters) else {
return nil
}


return encodedString


}


}

Use NSURLComponents to encode HTTP GET parameters:

    var urlComponents = NSURLComponents(string: "https://www.google.de/maps/")!
urlComponents.queryItems = [
NSURLQueryItem(name: "q", value: String(51.500833)+","+String(-0.141944)),
NSURLQueryItem(name: "z", value: String(6))
]
urlComponents.URL     // returns https://www.google.de/maps/?q=51.500833,-0.141944&z=6

http://www.ralfebert.de/snippets/ios/encoding-nsurl-get-parameters/

I faced a similar problem passing complex strings as a POST parameter. My strings can contain Asian characters, spaces, quotes and all sorts of special characters. The solution I eventually found was to convert my string into the matching series of unicodes, e.g. "Hu0040Hu0020Hu03f5...." using [NSString stringWithFormat:@"Hu%04x",[string characterAtIndex:i]] to get the Unicode from each character in the original string. The same can be done in Java.

This string can be safely passed as a POST parameter.

On the server side (PHP), I change all the "H" to "\" and I pass the resulting string to json_decode. Final step is to escape single quotes before storing the string into MySQL.

This way I can store any UTF8 string on my server.

Try to use stringByAddingPercentEncodingWithAllowedCharacters method with [NSCharacterSet URLUserAllowedCharacterSet] it will cover all the cases

Objective C

NSString *value = @"Test / Test";
value = [value stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLUserAllowedCharacterSet]];

swift

var value = "Test / Test"
value.stringByAddingPercentEncodingWithAllowedCharacters(NSCharacterSet.URLUserAllowedCharacterSet())

Output

Test%20%2F%20Test

-(NSString *)encodeUrlString:(NSString *)string {
return CFBridgingRelease(
CFURLCreateStringByAddingPercentEscapes(
kCFAllocatorDefault,
(__bridge CFStringRef)string,
NULL,
CFSTR("!*'();:@&=+$,/?%#[]"),
kCFStringEncodingUTF8)
);
}

according to the following blog

In my case where the last component was Arabic letters I did the following in 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;
}
}

usage:

let stringURL = "http://xxx.dev.com/endpoint/nonLatinCharacters"


if let encodedStringURL = stringURL.encodeUTF8() {


if let url = NSURL(string: encodedStringURL) {


...
}


}

This one is working for me.

func stringByAddingPercentEncodingForFormData(plusForSpace: Bool=false) -> String? {
let unreserved = "*-._"
let allowed = NSMutableCharacterSet.alphanumericCharacterSet()
allowed.addCharactersInString(unreserved)


if plusForSpace {
allowed.addCharactersInString(" ")
}


var encoded = stringByAddingPercentEncodingWithAllowedCharacters(allowed)
if plusForSpace {
encoded = encoded?.stringByReplacingOccurrencesOfString(" ",
withString: "+")
}
return encoded
}

I found the above function from this link: http://useyourloaf.com/blog/how-to-percent-encode-a-url-string/

You can also use this function with swift extension. Please let me know if there is any issue.

In Swift 3, please try out below:

let stringURL = "YOUR URL TO BE ENCODE";
let encodedURLString = stringURL.addingPercentEncoding(withAllowedCharacters: .urlHostAllowed)
print(encodedURLString)

Since, stringByAddingPercentEscapesUsingEncoding encodes non URL characters but leaves the reserved characters (like !*'();:@&=+$,/?%#[]), You can encode the url like the following code:

let stringURL = "YOUR URL TO BE ENCODE";
let characterSetTobeAllowed = (CharacterSet(charactersIn: "!*'();:@&=+$,/?%#[] ").inverted)
if let encodedURLString = stringURL.addingPercentEncoding(withAllowedCharacters: characterSetTobeAllowed) {
print(encodedURLString)
}

In swift 3:

// exclude alpha and numeric == "full" encoding
stringUrl = stringUrl.addingPercentEncoding(withAllowedCharacters: .alphanumerics)!;


// exclude hostname and symbols &,/ and etc
stringUrl = stringUrl.addingPercentEncoding(withAllowedCharacters: .urlHostAllowed)!;

After reading all the answers for this topic and the (wrong) accepted one, I want to add my contribution.

IF the target is iOS7+, and in 2017 it should since XCode makes really hard to deliver compatibility under iOS8, the best way, thread safe, fast, amd will full UTF-8 support to do this is:

(Objective C code)

@implementation NSString (NSString_urlencoding)


- (NSString *)urlencode {
static NSMutableCharacterSet *chars = nil;
static dispatch_once_t pred;


if (chars)
return [self stringByAddingPercentEncodingWithAllowedCharacters:chars];


// to be thread safe
dispatch_once(&pred, ^{
chars = NSCharacterSet.URLQueryAllowedCharacterSet.mutableCopy;
[chars removeCharactersInString:@"!*'();:@&=+$,/?%#[]"];
});
return [self stringByAddingPercentEncodingWithAllowedCharacters:chars];
}
@end

This will extend NSString, will exclude RFC forbidden characters, support UTF-8 characters, and let you use things like:

NSString *myusername = "I'm[evil]&want(to)break!!!$->àéìòù";
NSLog(@"Source: %@ -> Dest: %@", myusername, [myusername urlencode]);

That will print on your debug console:

Source: I'm[evil]&want(to)break!!!$->àéìòù -> Dest: I%27m%5Bevil%5D%26want%28to%29break%21%21%21%24-%3E%C3%A0%C3%A9%C3%AC%C3%B2%C3%B9

... note also the use of dispatch_once to avoid multiple initializations in multithread environments.

This code helped me for encoding special characters

NSString* encPassword = [password stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet alphanumericCharacterSet]];

Here's a production-ready flexible approach in Swift 5.x:

public extension CharacterSet {


static let urlQueryParameterAllowed = CharacterSet.urlQueryAllowed.subtracting(CharacterSet(charactersIn: "&?"))


static let urlQueryDenied           = CharacterSet.urlQueryAllowed.inverted()
static let urlQueryKeyValueDenied   = CharacterSet.urlQueryParameterAllowed.inverted()
static let urlPathDenied            = CharacterSet.urlPathAllowed.inverted()
static let urlFragmentDenied        = CharacterSet.urlFragmentAllowed.inverted()
static let urlHostDenied            = CharacterSet.urlHostAllowed.inverted()


static let urlDenied                = CharacterSet.urlQueryDenied
.union(.urlQueryKeyValueDenied)
.union(.urlPathDenied)
.union(.urlFragmentDenied)
.union(.urlHostDenied)




func inverted() -> CharacterSet {
var copy = self
copy.invert()
return copy
}
}






public extension String {
func urlEncoded(denying deniedCharacters: CharacterSet = .urlDenied) -> String? {
return addingPercentEncoding(withAllowedCharacters: deniedCharacters.inverted())
}
}

Example usage:

print("Hello, World!".urlEncoded()!)
print("You&Me?".urlEncoded()!)
print("#Blessed 100%".urlEncoded()!)
print("Pride and Prejudice".urlEncoded(denying: .uppercaseLetters)!)

Output:

Hello,%20World!
You%26Me%3F
%23Blessed%20100%25
%50ride and %50rejudice

Apple's advice, in the 10.11 release notes, is:

If you need to percent-encode an entire URL string, you can use this code to encode a NSString intended to be a URL (in urlStringToEncode):

NSString *percentEncodedURLString =
[[NSURL URLWithDataRepresentation:[urlStringToEncode dataUsingEncoding:NSUTF8StringEncoding] relativeToURL:nil] relativeString];

So many answers but didn't work for me, so I tried the following:

fun simpleServiceCall(for serviceUrl: String, appendToUrl: String) {
let urlString: String = serviceUrl + appendToUrl.addingPercentEncoding(withAllowedCharacters: .urlPathAllowed)!


let finalUrl = URL(string: urlString)!


//continue to execute your service call...
}

Hopefully it'll help someone. thanks

For the php function urlencode encoding a NSString to a cString with UTF8Encode, like [NSString UTF8String] was not working.

Here is my custom objective c NSString+ASCIIencode Category with works with all ASCII values 0..255

Header

#import <Cocoa/Cocoa.h>


@interface NSString (ASCIIEncode)


- (const char*)ASCIIEncode;


@end

Implementation

#import "NSString+ASCIIEncode.h"


@implementation NSString (ASCIIEncode)


- (const char*)ASCIIEncode {
    

static char output[1024];
    

// https://tools.piex.at/ascii-tabelle/
// https://www.ionos.de/digitalguide/server/knowhow/ascii-american-standard-code-for-information-interchange/
    

NSMutableArray *ascii = [NSMutableArray new];
// Hex
// 000                          Dez Hex
[ascii addObject:@"\0"]; // 000 000 NUL
[ascii addObject:@( 1)]; // 001 001 SOH
[ascii addObject:@( 2)]; // 002 002 STX
[ascii addObject:@( 3)]; // 003 003 ETX
[ascii addObject:@( 4)]; // 004 004 EOT
[ascii addObject:@( 5)]; // 005 005 ENQ
[ascii addObject:@( 6)]; // 006 006 ACK
[ascii addObject:@"\a"]; // 007 007 BEL
[ascii addObject:@"\b"]; // 008 008 BS
[ascii addObject:@( 9)]; // 009 009 TAB
[ascii addObject:@"\n"]; // 010 00A LF
[ascii addObject:@(11)]; // 011 00B VT
[ascii addObject:@(12)]; // 012 00C FF
[ascii addObject:@"\r"]; // 013 00D CR
[ascii addObject:@(14)]; // 014 00E SO
[ascii addObject:@(15)]; // 015 00F NAK
// 010
[ascii addObject:@(16)]; // 016 010 DLE
[ascii addObject:@(17)]; // 017 011 DC1
[ascii addObject:@(18)]; // 018 012 DC2
[ascii addObject:@(19)]; // 019 013 DC3
[ascii addObject:@(20)]; // 020 014 DC4
[ascii addObject:@(21)]; // 021 015 NAK
[ascii addObject:@(22)]; // 022 016 SYN
[ascii addObject:@(23)]; // 023 017 ETB
[ascii addObject:@(24)]; // 024 018 CAN
[ascii addObject:@(25)]; // 025 019 EM
[ascii addObject:@(26)]; // 026 01A SUB
[ascii addObject:@(27)]; // 027 01B ESC
[ascii addObject:@(28)]; // 028 01C FS
[ascii addObject:@(29)]; // 029 01D GS
[ascii addObject:@(30)]; // 030 01E RS
[ascii addObject:@(31)]; // 031 01F US
// 020
[ascii addObject:@" "];  // 032 020 Space
[ascii addObject:@"!"];  // 033 021
[ascii addObject:@"\""]; // 034 022
[ascii addObject:@"#"];  // 035 023
[ascii addObject:@"$"];  // 036 024
[ascii addObject:@"%"];  // 037 025
[ascii addObject:@"&"];  // 038 026
[ascii addObject:@"'"];  // 039 027
[ascii addObject:@"("];  // 040 028
[ascii addObject:@")"];  // 041 029
[ascii addObject:@"*"];  // 042 02A
[ascii addObject:@"+"];  // 043 02B
[ascii addObject:@","];  // 044 02C
[ascii addObject:@"-"];  // 045 02D
[ascii addObject:@"."];  // 046 02E
[ascii addObject:@"/"];  // 047 02F
// 030
[ascii addObject:@"0"];  // 048 030
[ascii addObject:@"1"];  // 049 031
[ascii addObject:@"2"];  // 050 032
[ascii addObject:@"3"];  // 051 033
[ascii addObject:@"4"];  // 052 034
[ascii addObject:@"5"];  // 053 035
[ascii addObject:@"6"];  // 054 036
[ascii addObject:@"7"];  // 055 037
[ascii addObject:@"8"];  // 056 038
[ascii addObject:@"9"];  // 057 039
[ascii addObject:@":"];  // 058 03A
[ascii addObject:@";"];  // 059 03B
[ascii addObject:@"<"];  // 060 03C
[ascii addObject:@"="];  // 061 03D
[ascii addObject:@">"];  // 062 03E
[ascii addObject:@"?"];  // 063 03F
// 040
[ascii addObject:@"@"];  // 064 040
[ascii addObject:@"A"];  // 065 041
[ascii addObject:@"B"];  // 066 042
[ascii addObject:@"C"];  // 067 043
[ascii addObject:@"D"];  // 068 044
[ascii addObject:@"E"];  // 069 045
[ascii addObject:@"F"];  // 070 046
[ascii addObject:@"G"];  // 071 047
[ascii addObject:@"H"];  // 072 048
[ascii addObject:@"I"];  // 073 049
[ascii addObject:@"J"];  // 074 04A
[ascii addObject:@"K"];  // 075 04B
[ascii addObject:@"L"];  // 076 04C
[ascii addObject:@"M"];  // 077 04D
[ascii addObject:@"N"];  // 078 04E
[ascii addObject:@"O"];  // 079 04F
// 050
[ascii addObject:@"P"];  // 080 050
[ascii addObject:@"Q"];  // 081 051
[ascii addObject:@"R"];  // 082 052
[ascii addObject:@"S"];  // 083 053
[ascii addObject:@"T"];  // 084 054
[ascii addObject:@"U"];  // 085 055
[ascii addObject:@"V"];  // 086 056
[ascii addObject:@"W"];  // 087 057
[ascii addObject:@"X"];  // 088 058
[ascii addObject:@"Y"];  // 089 059
[ascii addObject:@"Z"];  // 090 05A
[ascii addObject:@"["];  // 091 05B
[ascii addObject:@"\\"]; // 092 05C
[ascii addObject:@"]"];  // 093 05D
[ascii addObject:@"^"];  // 094 05E
[ascii addObject:@"_"];  // 095 05F
// 060
[ascii addObject:@"`"];  // 096 060
[ascii addObject:@"a"];  // 097 061
[ascii addObject:@"b"];  // 098 062
[ascii addObject:@"c"];  // 099 063
[ascii addObject:@"d"];  // 100 064
[ascii addObject:@"e"];  // 101 065
[ascii addObject:@"f"];  // 102 066
[ascii addObject:@"g"];  // 103 067
[ascii addObject:@"h"];  // 104 068
[ascii addObject:@"i"];  // 105 069
[ascii addObject:@"j"];  // 106 06A
[ascii addObject:@"k"];  // 107 06B
[ascii addObject:@"l"];  // 108 06C
[ascii addObject:@"m"];  // 109 06D
[ascii addObject:@"n"];  // 110 06E
[ascii addObject:@"o"];  // 111 06F
// 070
[ascii addObject:@"p"];  // 112 070
[ascii addObject:@"q"];  // 113 071
[ascii addObject:@"r"];  // 114 072
[ascii addObject:@"s"];  // 115 073
[ascii addObject:@"t"];  // 116 074
[ascii addObject:@"u"];  // 117 075
[ascii addObject:@"v"];  // 118 076
[ascii addObject:@"w"];  // 119 077
[ascii addObject:@"x"];  // 120 078
[ascii addObject:@"y"];  // 121 079
[ascii addObject:@"z"];  // 122 07A
[ascii addObject:@"{"];  // 123 07B
[ascii addObject:@"|"];  // 124 07C
[ascii addObject:@"}"];  // 125 07D
[ascii addObject:@"~"];  // 126 07E
[ascii addObject:@(127)];// 127 07F DEL
// 080
[ascii addObject:@"€"];  // 128 080
[ascii addObject:@(129)];// 129 081
[ascii addObject:@"‚"];  // 130 082
[ascii addObject:@"ƒ"];  // 131 083
[ascii addObject:@"„"];  // 132 084
[ascii addObject:@"…"];  // 133 085
[ascii addObject:@"†"];  // 134 086
[ascii addObject:@"‡"];  // 135 087
[ascii addObject:@"ˆ"];  // 136 088
[ascii addObject:@"‰"];  // 137 089
[ascii addObject:@"Š"];  // 138 08A
[ascii addObject:@"‹"];  // 139 08B
[ascii addObject:@"Œ"];  // 140 08C
[ascii addObject:@(141)];// 141 08D
[ascii addObject:@"Ž"];  // 142 08E
[ascii addObject:@(143)];  // 143 08F
// 090
[ascii addObject:@(144)];// 144 090
[ascii addObject:@"‘"];  // 145 091
[ascii addObject:@"’"];  // 146 092
[ascii addObject:@"“"];  // 147 093
[ascii addObject:@"”"];  // 148 094
[ascii addObject:@"•"];  // 149 095
[ascii addObject:@"–"];  // 150 096
[ascii addObject:@"—"];  // 151 097
[ascii addObject:@"˜"];  // 152 098
[ascii addObject:@"™"];  // 153 099
[ascii addObject:@"š"];  // 154 09A
[ascii addObject:@"›"];  // 155 09B
[ascii addObject:@"œ"];  // 156 09C
[ascii addObject:@(157)];// 157 09D
[ascii addObject:@"ž"];  // 158 09E
[ascii addObject:@"Ÿ"];  // 159 09F
// 0A0
[ascii addObject:@(160)];// 160 0A0
[ascii addObject:@"¡"];  // 161 0A1
[ascii addObject:@"¢"];  // 162 0A2
[ascii addObject:@"£"];  // 163 0A3
[ascii addObject:@"¤"];  // 164 0A4
[ascii addObject:@"¥"];  // 165 0A5
[ascii addObject:@"¦"];  // 166 0A6
[ascii addObject:@"§"];  // 167 0A7
[ascii addObject:@"¨"];  // 168 0A8
[ascii addObject:@"©"];  // 169 0A9
[ascii addObject:@"ª"];  // 170 0AA
[ascii addObject:@"«"];  // 171 0AB
[ascii addObject:@"¬"];  // 172 0AC
[ascii addObject:@(173)];// 173 0AD
[ascii addObject:@"®"];  // 174 0AE
[ascii addObject:@"¯"];  // 175 0AF
// 0B0
[ascii addObject:@"°"];  // 176 0B0
[ascii addObject:@"±"];  // 177 0B1
[ascii addObject:@"²"];  // 178 0B2
[ascii addObject:@"³"];  // 179 0B3
[ascii addObject:@"´"];  // 180 0B4
[ascii addObject:@"µ"];  // 181 0B5
[ascii addObject:@"¶"];  // 182 0B6
[ascii addObject:@"·"];  // 183 0B7
[ascii addObject:@"¸"];  // 184 0B8
[ascii addObject:@"¹"];  // 185 0B9
[ascii addObject:@"º"];  // 186 0BA
[ascii addObject:@"»"];  // 187 0BB
[ascii addObject:@"¼"];  // 188 0BC
[ascii addObject:@"½"];  // 189 0BD
[ascii addObject:@"¾"];  // 190 0BE
[ascii addObject:@"¿"];  // 191 0BF
// 0C0
[ascii addObject:@"À"];  // 192 0C0
[ascii addObject:@"Á"];  // 193 0C1
[ascii addObject:@"Â"];  // 194 0C2
[ascii addObject:@"Ã"];  // 195 0C3
[ascii addObject:@"Ä"];  // 196 0C4
[ascii addObject:@"Å"];  // 197 0C5
[ascii addObject:@"Æ"];  // 198 0C6
[ascii addObject:@"Ç"];  // 199 0C7
[ascii addObject:@"È"];  // 200 0C8
[ascii addObject:@"É"];  // 201 0C9
[ascii addObject:@"Ê"];  // 202 0CA
[ascii addObject:@"Ë"];  // 203 0CB
[ascii addObject:@"Ì"];  // 204 0CC
[ascii addObject:@"Í"];  // 205 0CD
[ascii addObject:@"Î"];  // 206 0CE
[ascii addObject:@"Ï"];  // 207 0CF
// 0D0
[ascii addObject:@"Ð"];  // 208 0D0
[ascii addObject:@"Ñ"];  // 209 0D1
[ascii addObject:@"Ò"];  // 210 0D2
[ascii addObject:@"Ó"];  // 211 0D3
[ascii addObject:@"Ô"];  // 212 0D4
[ascii addObject:@"Õ"];  // 213 0D5
[ascii addObject:@"Ö"];  // 214 0D6
[ascii addObject:@"×"];  // 215 0D7
[ascii addObject:@"Ø"];  // 216 0D8
[ascii addObject:@"Ù"];  // 217 0D9
[ascii addObject:@"Ú"];  // 218 0DA
[ascii addObject:@"Û"];  // 219 0DB
[ascii addObject:@"Ü"];  // 220 0DC
[ascii addObject:@"Ý"];  // 221 0DD
[ascii addObject:@"Þ"];  // 222 0DE
[ascii addObject:@"ß"];  // 223 0DF
// 0E0
[ascii addObject:@"à"];  // 224 0E0
[ascii addObject:@"á"];  // 225 0E1
[ascii addObject:@"â"];  // 226 0E2
[ascii addObject:@"ã"];  // 227 0E3
[ascii addObject:@"ä"];  // 228 0E4
[ascii addObject:@"å"];  // 229 0E5
[ascii addObject:@"æ"];  // 230 0E6
[ascii addObject:@"ç"];  // 231 0E7
[ascii addObject:@"è"];  // 232 0E8
[ascii addObject:@"é"];  // 233 0E9
[ascii addObject:@"ê"];  // 234 0EA
[ascii addObject:@"ë"];  // 235 0EB
[ascii addObject:@"ì"];  // 236 0EC
[ascii addObject:@"í"];  // 237 0ED
[ascii addObject:@"î"];  // 238 0EE
[ascii addObject:@"ï"];  // 239 0EF
// 0F0
[ascii addObject:@"ð"];  // 240 0F0
[ascii addObject:@"ñ"];  // 241 0F1
[ascii addObject:@"ò"];  // 242 0F2
[ascii addObject:@"ó"];  // 243 0F3
[ascii addObject:@"ô"];  // 244 0F4
[ascii addObject:@"õ"];  // 245 0F5
[ascii addObject:@"ö"];  // 246 0F6
[ascii addObject:@"÷"];  // 247 0F7
[ascii addObject:@"ø"];  // 248 0F8
[ascii addObject:@"ù"];  // 249 0F9
[ascii addObject:@"ú"];  // 250 0FA
[ascii addObject:@"û"];  // 251 0FB
[ascii addObject:@"ü"];  // 252 0FC
[ascii addObject:@"ý"];  // 253 0FD
[ascii addObject:@"þ"];  // 254 0FE
[ascii addObject:@"ÿ"];  // 255 0FF
    

NSInteger i;
    

for (i=0; i < self.length; i++) {
        

NSRange range;
range.location = i;
range.length = 1;
        

NSString *charString = [self substringWithRange:range];
        

for (NSInteger asciiIdx=0; asciiIdx < ascii.count; asciiIdx++) {
            

if ([charString isEqualToString:ascii[asciiIdx]]) {
unsigned char c = (unsigned char)asciiIdx;
output[i] = c;
break;
}
            

}
}
    

// Don't forget string termination
output[i] = 0;


return (const char*)&output[0];
}


@end

This is what I did using Swift 5:

func formatPassword() -> String {
    

var output = "";


for ch in self {


let char = String(ch)


switch ch {


case " ":
output.append("+")


break


case ".", "-", "_", "~", "a"..."z", "A"..."Z", "0"..."9":


output.append(char)


break


default:


print(ch)


let unicode = char.unicodeScalars.first?.value ?? 0


let unicodeValue = NSNumber(value: unicode).intValue


let hexValue = String(format: "%02X", arguments: [unicodeValue])


output = output.appendingFormat("%%%@", hexValue)


}


}
    

return output as String
}

Then I called this function where I defined my password.