[core] fix incorrect conversion of valid url

packages/expo-modules-core/CHANGELOG.md

@@ -9,6 +9,7 @@
 ### 🐛 Bug fixes
 
 - Fix the `View cannot be cast to ViewGroup` exception on Android. ([#23264](https://github.com/expo/expo/pull/23264) by [@lukmccall](https://github.com/lukmccall))
+- [iOS] Fix conversion to `URL` type that failed despite receiving a string that contained a valid URL. ([#23331](https://github.com/expo/expo/pull/23331) by [@alanhughes](https://github.com/alanjhughes))
 
 ### 💡 Others
 

packages/expo-modules-core/ios/Swift/Arguments/Convertibles.swift

@@ -17,10 +17,9 @@ extension URL: Convertible {
       throw Conversions.ConvertingException<URL>(value)
     }
 
-    // Try to construct the URL object from the string as it came in.
-    if let url = URL(string: value) {
-      // If it has no scheme, we assume it was the file path which needs to be recreated to be recognized as the file url.
-      return url.scheme != nil ? url : URL(fileURLWithPath: value)
+    // First we try to create a URL without extra encoding, as it came.
+    if let url = convertToUrl(string: value) {
+      return url
     }
 
     // File path doesn't need to be percent-encoded.
@@ -29,8 +28,8 @@ extension URL: Convertible {
     }
 
     // If we get here, the string is not the file url and may require percent-encoding characters that are not URL-safe according to RFC 3986.
-    if let encodedValue = percentEncodeUrlString(value), let url = URL(string: encodedValue) {
-      return url.scheme != nil ? url : URL(fileURLWithPath: value)
+    if let encodedValue = percentEncodeUrlString(value), let url = convertToUrl(string: encodedValue) {
+      return url
     }
 
     // If it still fails to create the URL object, the string possibly contains characters that must be explicitly percent-encoded beforehand.

packages/expo-modules-core/ios/Swift/Utilities.swift

@@ -58,3 +58,13 @@ internal func isFileUrlPath(_ path: String) -> Bool {
   }
   return URL(string: encodedPath)?.scheme == nil
 }
+
+internal func convertToUrl(string value: String) -> URL? {
+  // URLComponents parses and constructs URLs according to RFC 3986.
+  // For some unusual urls URL(string:) will fail incorrectly
+  guard let url = URLComponents(string: value)?.url ?? URL(string: value) else {
+    return nil
+  }
+  // If it has no scheme, we assume it was the file path which needs to be recreated to be recognized as the file url.
+  return url.scheme != nil ? url : URL(fileURLWithPath: value)
+}

packages/expo-modules-core/ios/Tests/ConvertiblesSpec.swift

@@ -71,13 +71,6 @@ class ConvertiblesSpec: ExpoSpec {
         }
       }
 
-      it("throws when url contains percent alone") {
-        // The percent character alone must be percent-encoded to `%25` beforehand, otherwise it should throw an exception.
-        let urlString = "https://expo.dev/?param=%"
-
-        expect({ try URL.convert(from: urlString, appContext: appContext) }).to(throwError(errorType: UrlContainsInvalidCharactersException.self))
-      }
-
       it("converts from url containing the anchor") {
         // The hash is not allowed in the query (requires percent-encoding),
         // but we want it to be recognized as the beginning of the fragment,