Instead of encoding a space as “%20,” you can use the plus sign reserved character to represent a space. For example, the URL “http://www.example.com/products%20and%20services.html” can also be encoded as http://www.example.com/products+and+services.html.
URL encoding converts characters into a format that can be transmitted over the Internet. - w3Schools. So, "/" is actually a seperator, but "%2f" becomes an ordinary character that simply represents "/" character in element of your url. Follow this answer to receive notifications.
In Python 3+, You can URL encode any string using the quote() function provided by urllib. parse package. The quote() function by default uses UTF-8 encoding scheme.
So you can test if the string contains a colon, if not, urldecode it, and if that string contains a colon, the original string was url encoded, if not, check if the strings are different and if so, urldecode again and if not, it is not a valid URI.
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/
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 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
}
}
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