I'm seeing an issue where I'm running the below multiple times with different URLs, and I'm getting the same data back 'sometimes' (it seems random). I'm wondering if iOS is caching some pages and giving me back the same data and not actually going to the URL.
Is there a cache? If so, is there a way to clear it before each call?
if let dataString = try? Data(contentsOf: url!) {
let pageContent = String(data: dataString, encoding: String.Encoding.utf8)
}
Take a look at init(contentsOf:options:) which provides an option called NSData.ReadingUncached. That's evidence that the simple form is cached and an answer to how you can control whether its cached.
A better approach with even more control is via URLSession
There are some cached files in the cache directory - print FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask).first!
After loading an image from a remote url, I added an extension .jpg to the cached file name. And I could see the image.
I have a webView in my ViewController. I have created a BullsEye.html file in my project and I want to show that html file in my web view. Following is my code
if let url = Bundle.main.url(forResource: "BullsEye",
withExtension: "html") {
if let htmlData = try? Data(contentsOf: url) {
let baseURL = URL(fileURLWithPath: Bundle.main.bundlePath)
webView.load(htmlData, mimeType: "text/html",
textEncodingName: "UTF-8", baseURL: baseURL)
}
}
The above code is written in viewDidLoad. What am I missing?
I ran your code as is and was able to make things work as seen here after changing the webView loader code. This tells me you likely have a UIWebView lurking somewhere, likely your view in storyboard.
I would recommend you make sure that you are consistently using WKWebView throughout:
Import WebKit in your class file
Have a valid output link to it if you are using a storyboard
If using a storyboard, ensure that you are using WKWebView and not the deprecated UIWebView
There is no problem with your source code itself, I think.
But maybe does Bundle.main.url(forResource: "BullsEye", withExtension: "html") return nil?
If so, you should check for the two things below:
Whether the file to be read is included in Copy Bundle Resources
Files to be included in the project are registered in TARGETS> Build Phases> Copy Bundle Resources.
Whether the file to be read exists in the project directory
Open the project directory in the Finder and check if the file you are trying to load actually exists.
Hope this helps!
Below code will help you.
func loadHtmlFile() {
if let fileurl = Bundle.main.url(forResource: "BullsEye", withExtension: "html") {
let request = URLRequest(url: fileurl!)
webView.loadRequest(request)
}
}
See - swiftdeveloperblog
Also if the code don't seem to work for you, make sure to open html file in any browser and check if it's a valid html file.
Apple's recommendation:
In apps that run in iOS 8 and later, use the WKWebView class instead of using UIWebView.
Thus, I have replaced my good old UIWebView with a shiny new WKWebView. But what I thought to be an easy exercise (simply swapping the classes and replacing the delegate methods) turned out to be a real mess.
The Problem
When I load an HTML string using
loadHTMLString(String, baseURL: URL?)
the web view loads and renders the pure HTML but it doesn't load any images or CSS files referenced inside the htmlString.
This happens only on a real device!
In Simultor all referenced resources are loaded correctly.
Example
I have defined a simple htmlString in my view controller class:
let imageName = "image.png"
let libraryURL: URL // The default Library URL
var htmlString: String {
return "<html> ... <img src=\"\(imageName)\" /> ... </html>"
// "..." represents more valid HTML code incl. header and body tags
}
The image is stored in the root Library folder so its URL is:
let imageURL = libraryURL.appendingPathComponent(imageName)
Now I load the htmlString into the web view:
webView.loadHTMLString(htmlString, baseURL: libraryURL)
and it doesn't load the image even though the baseURL is set correctly.
Ideas for a Solution
Maybe WKWebView has a problem with resolving relative paths so my first idea was to use absolute paths inside the HTML string instead.
→ ❌ Doesn't work.
Two answers to another SO post suggested that using
loadFileURL(URL, allowingReadAccessTo: URL)
instead of loadHTMLString(...) works in iOS 9+.
→ ✅ That works.
However, I cannot use solution 2 because my HTML files are encrypted and the decrypted files must not be stored on the disk.
Question
Is there any way to load local resources like images and styles using the WKWebView's
loadHTMLString(String, baseURL: URL?)
function? Or is still a bug in iOS 9+?
(I just cannot believe that Apple provides and recommends using a web view that cannot load any local web content from inside an HTML string?!)
Without taking a look at your actual project it's difficult to give some hundreed percent sure advices.
However:
class ViewController: UIViewController {
var webView = WKWebView()
override func viewDidLoad() {
super.viewDidLoad()
webView.translatesAutoresizingMaskIntoConstraints = false
let views = [
"webView" : webView
]
view.addSubview(webView)
var constraints = NSLayoutConstraint.constraintsWithVisualFormat("H:|[webView]|", options: [.AlignAllLeading, .AlignAllTrailing], metrics: nil, views: views)
constraints.appendContentsOf(NSLayoutConstraint.constraintsWithVisualFormat("V:|[webView]|", options: [.AlignAllTop, .AlignAllBottom], metrics: nil, views: views))
NSLayoutConstraint.activateConstraints(constraints)
let path = NSBundle.mainBundle().pathForResource("ios - WKWebView fails to load images and CSS using loadHTMLString(_, baseURL_) - Stack Overflow", ofType: "htm")
let url = NSURL(fileURLWithPath: path!)
webView.loadHTMLString(try! String(contentsOfURL: url), baseURL: url.URLByDeletingLastPathComponent)
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
I think the key point here is baseUrl parameter, you should setup it correctly. In my case i've used html's url without last path component - e.g. containing folder. This works fine on both device & simulator - check device snapshot. I've uploaded sample project to https://github.com/soxjke/WKWebViewTest so you can take a look (i've removed codesigning info from git)
So, to recap - method is working, functionality is working, just you do something wrong with it. To help you get what's wrong with your solutions, i'll add some suggestions:
1. Remember, that simulator filesystem is case-insensitive, device filesystem is case-sensitive. So if you have your filenames in html in lowercase - this won't work on device. 8fFsD.png != 8ffsd.png
2. Remember, that when copying resources, XCode ignores your folder structure. So if your html has <img src="./img/1.png"> and your XCOde project has folder structure like
test.htm
img/
1.png
2.png
After build it will be flattened, so test.htm and 1.png and 2.png will reside on same level
test.htm
1.png
2.png
I'm almost sure, after you verify these two assumptions, you'll get this method working.
I had this problem today, I've found the solution and potentially the cause:
loadHTMLString(String, baseURL: URL?)
This function doesn't allow the rendered HTML to access local media, as far as I'm aware, this is because it would be an injection risk, this could allow rendered HTML to access and manipulate your local file system. With a html string, that could come from anywhere or anyone.
loadFileURL(URL, allowingReadAccessTo: URL)
With this function, you point the WKWebview to the html file in your FileManager, and to the containing folder with 'allowingReadAccessTo'. Because the html is stored within the FileManager, it will allow the rendered HTML to access locally stored media.
If you don't have the html file stored locally for some reason(I assume you do), You could write the html sting into a .html file, then point to the URL of that file. However, this is just subverting Apple's protection, so do it at your own peril (don't do it).
This is just the solution that worked for me and my understanding of why we're having the problem to begin with.
Edit #1: Typo.
Edit #2: I've since found another nuance, When stating the 'allowingReadAccessTo:' URL, if the HTML itself needs to access things in parent folders (ie: .css, .js files), you need to specify the parent folder, not necessarily the location of the HTML itself, this will then implicitly allow access to the child folders as required also. For me, this problem was only apparent on a physical device, this didn't seem to have an effect whilst running in simulator, likely another discrepancy between how permissions work on simulator and a physical device.
Personally, I had to switch to using XWebView as the out-of-the-box behavior of WKWebView does not allow loading of local files. XWebView tricks it by loading up a local web server in the background and directing local traffic thru it. (XWebView is based on top of WKWebView)
Seems a bit overkill, but that is what I ended up having to do.
I've been experimenting with this as well, with similar restrictions, and the problem appears to be that paths aren't resolved unless baseURL references the application bundle. It doesn't work if you, for example, have something in the application's documents.
Edit: I have filed a radar for this rdar://29130863
Well you should be able to use local images and CSS files (and JavaScript files for that matter) with WKWebViews with the function that you have already found. My guess is that the problem is with your baseURL variable.
Update 7.5.2017:
I have completely updated the code from another SO answer of mine that used to be linked to my answer here. I have a working project for loadHTMLString() and .loadFileURL()
Try to create baseURL using:
let baseURL = URL(fileURLWithPath: "#path#")
instead of:
let baseURL = URL(string: "#path#")
The main difference is that the first method adds file:// prefix before the path.
You can base64 encode the images... I know that works. Not sure if it will be appropriate for your use case though.
Kind of funny, I just ran into this problem while doing the opposite - moving from base64 encoded to image files.
When I used UIWebview, I used baseURL as,
let baseUrl = NSURL(string: Bundle.main.path(forResource: "cms", ofType: "html")!)! as URL
webView.loadHTMLString(bodyPage, baseURL: baseUrl)
But for the WKWebView, I used baseURL as
let baseUrl = Bundle.main.bundleURL
webView.loadHTMLString(bodyPage, baseURL: baseUrl)
This works for me.
I know this is quite old already, but I ran into the exact same problem and it took me hours of trials and even to find this thread with the same problem (Xamarin Forms App)
My issue was: parsing remote HTML content into a string and also adding locally saved images (also downloaded dynamically, no resource of the app). On the simulator all works well, but on acutal device the local images are not showing (also no ? or anything indicating an error, just a blank frame). The Xamarin webview also offers the "BaseURL" option which didn't help, also not to use the BaseURL on the custom iOS wkWebView.
The only working solution as pointed out by Scott above, is to write the HTML into a file and then use the "LoadFileUrl" function and allow read access to the base directory. This also works with absolute file paths for images in the HTML (not only relative to the basedir, but of course somewhere within the basedir).
My custom webview renderer to load web and local content looks like this now:
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e) {
base.OnElementPropertyChanged(sender, e);
NSUrl baseURL = new NSUrl(App.dirNews, true);
string viewFile = Path.Combine(App.dirNews, "view.html");
NSUrl fileURL = new NSUrl(viewFile, false);
switch (e.PropertyName) {
case "Url":
System.Console.WriteLine("--- Loading Web page ---");
System.Console.WriteLine("--- " + Element.Url + " ---");
NSUrlRequest myRequest = new NSUrlRequest(new NSUrl(Element.Url), NSUrlRequestCachePolicy.ReloadIgnoringLocalAndRemoteCacheData, 120);
Control.LoadRequest(myRequest);
break;
case "HTML":
System.Console.WriteLine("--- Showing HTTP content ---");
File.WriteAllText(viewFile, Element.HTML, System.Text.Encoding.UTF8);
Control.LoadFileUrl(fileURL, baseURL);
break;
}
}
I was able to reproduce a similar issue. WKWebView loads my images specially if they are located remotely, apart from my app server.
For servers that are not SSL-secured (http instead of https), you can set your info.plist as per below:
App Transport Security Settings
- Allow Arbitrary Loads in Web Content (Set to YES)
- Allow Arbitrary Loads (Set to YES)
The problem was actually in the server. The server application was either:
Changing the image src from "http://IP-or-domain/uploads/file.jpg" to "../../uploads/file.jpg"
- OR -
The image src was "http://localhost/uploads/file.jpg" or "http://127.0.0.1/uploads/file.jpg" instead of "http://YOUR-SERVER-IP-ADDRESS/uploads/file.jpg"
In these cases, the actual device wont be able to locate the image. This only works with iOS Simulator because the virtual device is the same as the server and development machine. It can read LOCALHOST and 127.0.0.1.
In my server, I was using a Rich Text Editor (TinyMCE) and it automatically removes the IP address after it detects that it's the same source.
WKWebView can load image or css file from NSTemporaryDirectory, so you can copy your files to NSTemporaryDirectory, and then load it. It works for me on iOS 14! see this issue. ios-wkwebview-loadhtmlstring-baseurl-fails-to-load-images-and-read-css
It took me a while to figure this out, but based on this answer I got it working:
https://stackoverflow.com/a/73519282/5868066
Try this:
let htmlPath = URL(fileURLWithPath: "")
let htmlDirectory = htmlPath.deletingLastPathComponent()
let htmlString = try! String(contentsOfFile: htmlPath.path, encoding: .utf8)
let baseURL = URL(fileURLWithPath: htmlDirectory)
let documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[.zero]
webView.loadFileURL(htmlPath, allowingReadAccessTo: documentsDirectory)
webView.loadHTMLString(htmlString, baseURL: baseURL)
I am using
let data = try?
NSString(contentsOfFile: "/Users/BenA**** 1/Desktop/textFile.txt",
encoding: String.Encoding.utf8.rawValue)
to access a file on my computer. When I test put the app on my phone, it obviously didn't work because it didn't have access to the file. How could I put this file on my phone and be able to access it from there? Thanks.
Include your "textFile.txt" in main bundle by drag and drop file in to xcode project, then access it by
class testViewController: UIViewController{
var data:String = ""
override func viewDidLoad() {
super.viewDidLoad()
let path = NSBundle.mainBundle().pathForResource("textFile", ofType: "txt")
data = try? NSString(contentsOfFile: path!, encoding: ENCODING)
}}
Try this way to access 'data' in rest of code.
Hope this help.
To simulate the behavior of iOS enable the sandbox on macOS.
Now you can access files only in the container of the app.
Nevertheless the predefined folders like Documents, Library etc. still exist.
To have access to that directories there a method of NSFileManager. For example one of the most important directories in iOS is the Documents directory.
let documentsFolderURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomain: .UserDomainMask).first!
You have to use that method each time you need to get the URL of that particular directory because for security reasons the absolute path will change.
I am having some issues when trying to run my app on an iPad (or any device) it runs as expected on the emulator so it is weird that it doesn't work on a device. I was wondering if some one could point me in the correct direction. I spend many hours reading all the other posts on here about the same issues, however none of the suggested solutions worked.
I have a WKWebView into which I am loading a local html file. On the emulator the file loads and everything works fine but on a device I am getting a message in the log:
Could not create a sandbox extension for '/'
Here is the code I have that loads the file into the
override func viewDidLoad() {
super.viewDidLoad()
var path = NSBundle.mainBundle().pathForResource("Login_UK",
ofType: "html")
var url = NSURL(fileURLWithPath: path!)
var request = NSURLRequest(URL: url!)
var theConfiguration = WKWebViewConfiguration()
theConfiguration.userContentController.addScriptMessageHandler(self,
name: "callbackHandler")
webView = WKWebView(frame: self.view.frame,
configuration: theConfiguration)
webView!.loadRequest(request)
self.view.addSubview(webView!)
}
Any help will be greatly appreciated
Kind Regards,
Dimitar
Thank you for any one who tried to answer my question. I have released that this is an error with the WebKit lib that Apple are trying to fix. However I have found a good workaround that required little work.
I open the local file and read its content and then send that string into a webView.loadHTMLString method that compiles the hmtl that was in the file. That way you avoid the issues with iOS not being able to find the path to the local file.
Here is an example of reading a file and then opening it for any one who has the same issues:
let path2 = NSBundle.mainBundle().pathForResource("index", ofType: "html")
var text = String(contentsOfFile: path2!, encoding: NSUTF8StringEncoding, error: nil)!
webView!.loadHTMLString(text, baseURL: url)
Kind regards,
Dimitar
Just do this:
if url.isFileURL {
webView.loadFileURL(url, allowingReadAccessTo: url)
} else {
let request = URLRequest(url: url)
webView.load(request)
}
There is a function loadFileURL on the WKWebView starting iOS 9 that apparently has to be used when reading data from a file URL.
Strange enough using the load function with an URLRequest for the file URL does work in the simulators, but not on device - the web view stays blank on the device. Using the loadFileURL works on device and the simulator.
Using loadHTMLString unfortunately introduces another problem (local anchors that jump to another position in the same web view are not working anymore) and probably should be avoided until Apple releases a fix for that issue.
Actually the problem is caused by the webView.load() function, if we test it on simulators it will work perfectly, but for the real device it may cause some problems and it will not load the webview perfectly. You may check it by calling the didFinish() function.
What you need to do is call webView.loadFileURL() rather than webView.load(). It will work in both simulators and real devices. This is very useful when you load any file from the local file directory.