Why My Return Is Nil But If I Press the Url in Chrome/Safari, I Can Get Data

Why my return is nil but if i press the url in chrome/safari, i can get data?

The text you try to get is probably not UTF-8, try with another encoding, like this for example:

let myString = NSString(data: data, encoding: NSASCIIStringEncoding)

Update: read Martin R's answer for how to find the right encoding.

iOS NSURL returning nil on valid URL

The problem is that you need to percent-encode your values in the URL string. When it’s received by the server, it will decode this percent-encoded string in the URL into the desired value.

But rather than percent-encoding yourself, you can use NSURLComponents. For example, if you want a to have the value of @"1\\tb", you can do:

NSURLComponents *components = [NSURLComponents componentsWithString:@"http://localhost:8080"];
components.queryItems = @[
    [NSURLQueryItem queryItemWithName:@"a" value:@"1\\tb"],
    [NSURLQueryItem queryItemWithName:@"b" value:@"2"]
];
NSURL *url = components.URL;

Yielding:

http://localhost:8080?a=1%5Ctb&b=2

Or, if you wanted it to have the tab character in the value associated with a (i.e. %09):

NSURLComponents *components = [NSURLComponents componentsWithString:@"http://localhost:8080"];
components.queryItems = @[
    [NSURLQueryItem queryItemWithName:@"a" value:@"1\tb"],
    [NSURLQueryItem queryItemWithName:@"b" value:@"2"]
];
NSURL *url = components.URL;

Yielding:

http://localhost:8080?a=1%09b&b=2

It just depends upon whether your server is expecting two characters, the \ followed by t (the first example) or the single \t character (the second example). Either way, the respective use of NSURLComponents will take care of the percent-encoding for you, and your server will decode it.

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For what it’s worth, the one caveat is the + character, which NSURLComponents won’t percent-encode for you (because, technically, a + character is allowed in a URL query). The problem is that the + character is interpreted as a space character by most web servers (per the x-www-form-urlencoded spec). If you need to pass a literal + character, you might want to replace those + characters, as advised by Apple:

NSURLComponents *components = [NSURLComponents componentsWithString:@"http://localhost:8080"];
components.queryItems = @[
    [NSURLQueryItem queryItemWithName:@"q" value:@"Romeo+Juliet"]
];
components.percentEncodedQuery = [components.percentEncodedQuery stringByReplacingOccurrencesOfString:@"+" withString:@"%2B"];
NSURL *url = components.URL;

NSString encoding returns nil on url content

The problem there as already mentioned by rmaddy it is the encoding you are using. You need to use NSASCIIStringEncoding.

if let url = URL(string: "https://www.google.com") {
    URLSession.shared.dataTask(with: url) {
        data, response, error in
        guard
            let httpURLResponse = response as? HTTPURLResponse, httpURLResponse.statusCode == 200,
            let data = data, error == nil,
            let urlContent = String(data: data, encoding: .ascii)
        else { return }
        print(urlContent)
    }.resume()
}

Or taking a clue from Martin R you can detect the string encoding from the response:

extension String {
    var textEncodingToStringEncoding: Encoding {
        return Encoding(rawValue: CFStringConvertEncodingToNSStringEncoding(CFStringConvertIANACharSetNameToEncoding(self as CFString)))
    }
}

---

if let url = URL(string: "https://www.google.com") {
    URLSession.shared.dataTask(with: url) {
        data, response, error in
        guard
            let httpURLResponse = response as? HTTPURLResponse, httpURLResponse.statusCode == 200,
            let data = data, error == nil,
            let textEncoding = response?.textEncodingName,
            let urlContent = String(data: data, encoding: textEncoding.textEncodingToStringEncoding)
            else { return }
        print(urlContent)
    }.resume()
}

NSURLSession does not returns data for http/https

This is a text encoding problem. The webpage at http://www.google.com/finance/converter?a=1&from=USD&to=INR is not encoded with UTF-8 but with ISO-8859-1.

In this case, you have to use NSISOLatin1StringEncoding instead of NSUTF8StringEncoding for NSString:

let webcontent = NSString(data: url_content, encoding: NSISOLatin1StringEncoding)

XCode swift HTTPS: String(data: data!, encoding: NSUTF8StringEncoding ) return nil

in my code usually make a fall back:

 var strData = NSString(data: data, encoding: NSUTF8StringEncoding)
 if (strData == nil){
    //roll back to ASCII ...
        strData = NSString(data: data, encoding: NSASCIIStringEncoding)
    }

xcode NSURLConnection post return 200 but NSData always null?

Status code 200 shows that you have now active and successful connection with the server. But that does not mean that you will get data successfully. There are some points needs to be take care:

1. Your request should match Content-Type required on server. If it is not match you will not receive data or invalid data

2. Make sure which method you have called GET or POST.

3. Some web-services are also required specific user-agent, So if it required check for user-agent also

4. Parameter values: Even if you get success code - The datatype values required to server some time mis lead to you. Most common possible datatype mis match are bool, int and float. It is essential to check that you have pass exact datatype value. e.g. 1 is consider as int and also as a bool value.

5. Encoding Scheme: You must have to parse receive data with exactly same encoding scheme as per server specification.

Edit:

In your case you just need to change encoding:NSASCIIStringEncoding.

-(void) connection:(NSURLConnection *)connection didReceiveData: (NSData *) incomingData
{
    NSLog(@"data---%@",[[NSString alloc] initWithData: incomingData encoding:NSASCIIStringEncoding]);

}

Replace above method with your code.

Swift get HTML from URL

It seems that www.google.com sends the response using the
ISO 8859-1 encoding, the corresponding NSString encoding is NSISOLatin1StringEncoding:

html = try NSString(contentsOfURL: testUrl!, encoding: NSISOLatin1StringEncoding)

You can also detect the HTTP response encoding automatically,
see for example https://stackoverflow.com/a/32051684/1187415.

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