Encode the style URL in iOS (#2965)

platform/darwin/src/http_file_source.mm

@@ -226,8 +226,9 @@ BOOL isValidMapboxEndpoint(NSURL *url) {
 MLN_APPLE_EXPORT
 NSURL *resourceURL(const Resource& resource) {
     
-    NSURL *url = [NSURL URLWithString:@(resource.url.c_str())];
-
+    NSString *encodedUrlString = [@(resource.url.c_str()) stringByAddingPercentEncodingWithAllowedCharacters:NSCharacterSet.URLQueryAllowedCharacterSet];
+    NSURL *url = [NSURL URLWithString:encodedUrlString];
+    
 #if TARGET_OS_IPHONE || TARGET_OS_SIMULATOR
     if (isValidMapboxEndpoint(url)) {
         NSURLComponents *components = [NSURLComponents componentsWithURL:url resolvingAgainstBaseURL:NO];

platform/darwin/test/MLNResourceTests.mm

@@ -86,4 +86,15 @@ namespace mbgl {
     [self internalTestOfflineQueryParameterIsAddedForOfflineResource:testURL];
 }
 
+- (void)testResourceURL {
+    using namespace mbgl;
+
+    // Test URL with characters requiring encoding
+    Resource resource(Resource::Kind::Unknown, "https://example.com/test?param1=a|b&param2=c|d");
+    NSURL *url = resourceURL(resource);
+
+    XCTAssertNotNil(url);
+    XCTAssertEqualObjects(url.absoluteString, @"https://example.com/test?param1=a%7Cb&param2=c%7Cd");
+}
+
 @end