Unable to convert string to URL in Swift iOS

Question

In order to make HTTP request call using URLSession,I need to convert string to URL first so I have tried everything but just can’t convert this piece of string to URL(string: ). This is the string: “http://api-aws-eu-qa-1.abc-cde.com/v1/car-types/manufacturer?page=0&pageSize=10&wa_key=abc-cde-efg-44ccd99”

I can’t share the exact Url but format is all same. The actual url with same format works fine in browser but no way in Swift, also that works fine in POSTMAN I have also tried URLComponents which hepls me create the URL from components to URL but that fails with 400 status code response error. I really appreciate the help, I am completely bogged down with this isuue and can’t proceed with my assignment.

Update: Tested with fiddler and request was not going through with this URL - "“http://api-aws-eu-qa-1.abc-cde.com%E2%80%8B/v1/car-types/manufacturer?page=0&pageSize=10&wa_key=abc-cde-efg-44ccd99”"

But when removed this %E2%80%8B in fiddler and resend it worked. Any thoughts ..?

Have you tried addingPercentEncoding or urlHostAlloqed or urlQuery allowed? — Rob, Jan 24 '22 at 15:51
If you don't print your api response all you can do is guessing. `print(Data(data: data, encoding: .utf8) ?? "")` — Leo Dabus, Jan 24 '22 at 16:08
`URL(string: "http://api-aws-eu-qa-1.abc-cde.com/v1/car-types/manufacturer?page=0&pageSize=10&wa_key=abc-cde-efg-44ccd99")` seems to create an URL without trouble. Do you have an example of a URL that actually fails? — Rob Napier, Jan 24 '22 at 16:13
I tried addingPercentEncoding with URLQuery, fragments and other ytpes but nothing worked, and when create URL using URLComponents it adds some special characters next to http://api-aws-eu-qa-1.abc-cde.com — gagan sharma, Jan 24 '22 at 16:13
Check your POSTMAN headers configuration. Are you doing a post or a get? — Leo Dabus, Jan 24 '22 at 16:13
What special characters does it add next to the host? When I try `URLComponents(string: "http://api-aws-eu-qa-1.abc-cde.com/v1/car-types/manufacturer?page=0&pageSize=10&wa_key=abc-cde-efg-44ccd99")`, it creates an URLComponents without trouble. Can you post code that demonstrates your problem? (You can't just call `addingPercentEncoding` to random parts of a String. It generally is not the right tool unless you know precisely what you're doing.) — Rob Napier, Jan 24 '22 at 16:15
@LeoDabus I am doing Get and used the Swift code snippet given by postman but that also crashes where URL is forming — gagan sharma, Jan 24 '22 at 16:16
Are you saying that it is returning `nil` from `URL(string:)` initializer? — Leo Dabus, Jan 24 '22 at 16:17
What happen when you compose your string using `URLComponents`? — Leo Dabus, Jan 24 '22 at 16:17
@RobNapier when I use print(urlComponents.url?.absoluteString) it shows this "http://api-aws-eu-qa-1.abc-cde.com%E2%80%8B/v1/car-types/manufacturer?page=0&pageSize=10&wa_key=abc-cde-efg-44ccd99" — gagan sharma, Jan 24 '22 at 16:18
special characters added by `URLComponents` shouldn't be an issue — Leo Dabus, Jan 24 '22 at 16:18
That looks like you called `addingPercentEncoding` blindly on the string. Don't do that. See Euan Traynor's answer for an example of how to use URLComponents. (But I expect the problem is in the specific URL you're trying to encode. You need to show us something that actually fails. I expect your string is just not a legal URL in the first place.) — Rob Napier, Jan 24 '22 at 16:19
@LeoDabus but in that case request fails with 400 status response but show json response when used in browser — gagan sharma, Jan 24 '22 at 16:20
As already stated by Rob make sure to pass the string to URLComponents without any percent encoding — Leo Dabus, Jan 24 '22 at 16:21
@gagansharma it doesnt mean anything. Safari does what you are not doing under the hood. — Leo Dabus, Jan 24 '22 at 16:21
@LeoDabus I am using URLComponents without any percent encoding — gagan sharma, Jan 24 '22 at 16:23
Show your code, how you construct the URL, even if you obfuscate some keys, base URL, etc. But at least try to keep "special characters" if there is... Like `http://myURL.com/path1/path2/query?key1=value_1&key2=value2`, etc. — Larme, Jan 24 '22 at 16:51
As Leo notes, the Safari address bar accepts a wide variety of strings that are not valid URLs. It has various ad hoc rules for deciding what to do with those strings. The string "example.com" is not a valid URL (it has no scheme), but if you type it into the Safari address bar, it will turn it into `http://example.com` and navigate to it. On the other hand, if I type just "example" (also not an URL), it will convert that to an URL for a web search. You cannot use the Safari address bar to determine if something is an URL. — Rob Napier, Jan 24 '22 at 17:02
If you cannot show us the specific string that fails, you need to show us *some* string that fails in a similar way. If you just say "I send a string to URL and it doesn't work," the answer is "that string isn't a valid URL." We can't help you beyond that without an example. You can read the rules at [RFC 3986 section 3](https://datatracker.ietf.org/doc/html/rfc3986#section-3) — Rob Napier, Jan 24 '22 at 17:04
"But when removed this %E2%80%8B in fiddler and resend it worked." Yes, because that's not part of a valid HTTP URL. When you connected to a host that didn't exist, it failed. When you edited the URL to connect to a host that does exist, it works. Where did you get this string from? — Rob Napier, Jan 24 '22 at 19:32

score 1 · Answer 1 · answered Jan 24 '22 at 16:02

1

String to URL

let url = URL(string: "the url string goes here")

URL to String

let url = URL(string: "the url string goes here")
let urlString = url.absoluteString

Creating URL from URLComponents

var url: URL? {
    var components = URLComponents()
    components.scheme = "https"
    components.host = "domain goes here" //example: twitter.com
    components.path = "/path/goes/here"
    components.queryItems = [
        URLQueryItem(name: "item1", value: string1),
        URLQueryItem(name: "item2", value: string2)
    ]

    return components.url
}

answered Jan 24 '22 at 16:02

Euan Traynor

420
2
11

OP have already tried using URLComponents – Leo Dabus Jan 24 '22 at 16:11
@LeoDabus It's not clear that the OP has used URLComponents correctly, however (and very likely has not). Demonstrating its use is very helpful. – Rob Napier Jan 24 '22 at 16:17
I am already using the same way but it adds %E2%80%8B symbols in Url, then fail – gagan sharma Jan 24 '22 at 18:44
You have an invisible character in your URL string. %E2%80%8B refers to the character "Zero Width Space" (Code point: U+200B). Try manually retyping in the URL string completely from scratch... or use the following method. `extension Character { static let zeroWidthSpace = Self(.init(0x200B)!) var isZeroWidthSpace: Bool { self == .zeroWidthSpace } }` and `extension Bool { var negated: Bool { !self }}` and finally call it `let filteredStringURL = str.filter(\.isZeroWidthSpace.negated)` – Euan Traynor Jan 24 '22 at 19:23

score 0 · Answer 2 · answered Jan 24 '22 at 16:01

0

try to add HEADER to you request:

let url = URL(string : urlString)
var request = URLRequest(url : url)
request.setValue("Application/json", forHTTPHeaderField : "Content-Type")

answered Jan 24 '22 at 16:01

AdR

572
1
4
13

this is irrelevant if OP is not posting anything – Leo Dabus Jan 24 '22 at 16:11
Correct setValue will have no effect here. – gagan sharma Jan 24 '22 at 18:45

Rob Napier · Answer 3 · 2022-01-24T19:30:51.223

Your URL is:

http://api-aws-eu-qa-1.abc-cde.com%E2%80%8B/v1/car-types/manufacturer?page=0&pageSize=10&wa_key=abc-cde-efg-44ccd99`

The "host" portion is:

api-aws-eu-qa-1.abc-cde.com%E2%80%8B

%E2%80%8B encodes a ZERO WIDTH SPACE. This is a perfectly valid URL:

URL(string: "http://api-aws-eu-qa-1.abc-cde.com%E2%80%8B/v1/car-types/manufacturer?page=0&pageSize=10&wa_key=abc-cde-efg-44ccd99")
=> Optional(http://api-aws-eu-qa-1.abc-cde.com%E2%80%8B/v1/car-types/manufacturer?page=0&pageSize=10&wa_key=abc-cde-efg-44ccd99)

However, there is no such host as api-aws-eu-qa-1.abc-cde.com%E2%80%8B, so you should expect the actual connection to fail.

I expect that whatever is generating your URL strings has a bug.

If you are having trouble creating the URL itself (if URL(string:) return nil, then I expect this is not your actual URL string.

If you construct an URLComponents, the results are correct but may be slightly misleading:

URLComponents(string: "http://api-aws-eu-qa-1.abc-cde.com%E2%80%8B/v1/car-types/manufacturer?page=0&pageSize=10&wa_key=abc-cde-efg-44ccd99")?.host
Optional("api-aws-eu-qa-1.abc-cde.com")

While this looks like "api-aws-eu-qa-1.abc-cde.com", the string actually has a ZERO WIDTH SPACE at the end, which is invisible (but still part of the host field, which will correctly fail if you try to connect to it).

Unable to convert string to URL in Swift iOS

3 Answers3