Fixing an issue with WK not loading referenced resources. (#320)

* Fixing an issue with WK not loading referenced resources.

* Switching to use NSURL to load html content

Author: milos1290

Leanplum-SDK/Classes/Features/Actions/LPActionContext.m

@@ -243,7 +243,7 @@ - (NSString *)fillTemplate:(NSString *)value
     return value;
 }
 
-- (NSString *)htmlWithTemplateNamed:(NSString *)templateName
+- (NSURL *)htmlWithTemplateNamed:(NSString *)templateName
 {
     if ([LPUtils isNullOrEmpty:templateName]) {
         [Leanplum throwError:@"[LPActionContext htmlWithTemplateNamed:] "
@@ -298,9 +298,19 @@ - (NSString *)htmlWithTemplateNamed:(NSString *)templateName
     }
     htmlString = [htmlString stringByReplacingOccurrencesOfString:@"##Vars##"
                                                        withString:jsonString];
-    return [self fillTemplate:htmlString];
+
+    htmlString = [self fillTemplate:htmlString];
+
+    // Save filled template to temp file which will be used by WebKit
+    NSString *randomUUID = [[[NSUUID UUID] UUIDString] lowercaseString];
+    NSString *tmpPath = [LPFileManager fileRelativeToDocuments:randomUUID createMissingDirectories:YES];
+    NSURL *tmpURL = [[NSURL fileURLWithPath:tmpPath] URLByAppendingPathExtension:@"html"];
+
+    [htmlString writeToURL:tmpURL atomically:YES encoding:NSUTF8StringEncoding error:nil];
+
+    return tmpURL;
     LP_END_TRY
-    return @"";
+    return nil;
 }
 
 - (NSString *)getDefaultValue:(NSString *)name

Leanplum-SDK/Classes/LPActionContext.h

@@ -35,7 +35,7 @@
 - (NSDictionary *)dictionaryNamed:(NSString *)name;
 - (NSArray *)arrayNamed:(NSString *)name;
 - (UIColor *)colorNamed:(NSString *)name;
-- (NSString *)htmlWithTemplateNamed:(NSString *)templateName;
+- (NSURL *)htmlWithTemplateNamed:(NSString *)templateName;
 
 /**
  * Runs the action given by the "name" key.

Leanplum-SDK/Classes/LPMessageTemplates.m

@@ -1219,8 +1219,20 @@ - (void)refreshPopupContent
                     [webView loadRequest:[NSURLRequest requestWithURL:
                                         [NSURL URLWithString:[context stringNamed:LPMT_ARG_URL]]]];
                 } else {
-                    NSString *html = [context htmlWithTemplateNamed:LPMT_ARG_HTML_TEMPLATE];
-                    [webView loadHTMLString:html baseURL:nil];
+                    if (@available(iOS 9.0, *))
+                    {
+                        NSURL *htmlURL = [context htmlWithTemplateNamed:LPMT_ARG_HTML_TEMPLATE];
+                        // Allow access to base folder.
+                        NSString *path = [LPFileManager documentsPath];
+                        NSURL* baseURL = [NSURL fileURLWithPath:path isDirectory:YES];
+
+                        [webView loadFileURL:htmlURL allowingReadAccessToURL:baseURL];
+                    }
+                    else
+                    {
+                        NSURL *htmlURL = [context htmlWithTemplateNamed:LPMT_ARG_HTML_TEMPLATE];
+                        [webView loadRequest:[NSURLRequest requestWithURL:htmlURL]];
+                    }
                 }
             }
         }