Search code examples
javascriptiosiphoneswiftwebview

Load local javascript in webview?

I'm making mobile browser with my own ads in Swift and I want to run script. I already inject JavaScript local file but it opens in other window and overrides webView content. Is it possible to run JavaScript code in webView page? Not in other window, only in page with page content.

Solution

  • Using WKWebView for javascript method call:

    Step 1. Import class for webkit

    Obj-C: #import <WebKit/WebKit.h>
    Swift: import WebKit

    Step 2. Create a WKWebView instance (Unfortunately it can only be done programatically)

    Obj-C @property (strong, nonatomic) WKWebView *wkWebView;

    Swift var wkWebView: WKWebView? = WKWebView()

    Step 3. Then in viewDidLoad

    Obj-C:

        WKWebViewConfiguration *configuration = [[WKWebViewConfiguration alloc] init];
    
    NSString *scriptSourceCode = @"your javascript code here";
    WKUserScript *script = [[WKUserScript alloc] initWithSource:source injectionTime:WKUserScriptInjectionTimeAtDocumentStart forMainFrameOnly:YES];

    WKUserContentController *controller = [[WKUserContentController alloc] init];
    [controller addUserScript:script];

    configuration.userContentController = controller;
    
    _wkWebView = [[WKWebView alloc] initWithFrame:self.view.frame configuration:configuration];
    
    [self.view addSubview:_wkWebView];

    Swift:

        let configuration = WKWebViewConfiguration()
    let controller = WKUserContentController()
    
    let scriptSourceCode = "your javascript code here"
    let script = WKUserScript(source: scriptSourceCode, injectionTime: WKUserScriptInjectionTime.AtDocumentStart, forMainFrameOnly: true)
    controller.addUserScript(script)

    configuration.userContentController = controller
    
    self.wkWebView = WKWebView(frame: self.view.frame, configuration: configuration)
    
    self.view.addSubview(self.wkWebView!)

    Step 4 Load a HTML string (or a loadRequest) in the wkWebView:

    Obj-C:

    [_wkWebView loadHTMLString:_desiredHTML baseURL:[[NSBundle mainBundle] bundleURL]];

    Swift:

    self.wkWebView?.loadHTMLString(_desiredHTML, baseURL: NSBundle.mainBundle().bundleURL)

    Step 5. Call a method which exists in the javascript included in the WKWebView

    Obj-C:

        NSString *callMethod = [NSString stringWithFormat:@"existingMethodWithParam(%@)", stringParam];

    [_wkWebView evaluateJavaScript:callMethod
             completionHandler:^(id obj, NSError *error) {
                 
                 if (error)
                 {
                     NSLog(@"ERROR evaluating JavaScript - %@", error);
                 }
                 else 
                 {
                     NSLog(@"Returned value - %@", obj); //if the javascript method has a return type
                 }
             }];

    Swift:

    let callMethod = "existingMethodWithParam()"
self.wkWebView?.evaluateJavaScript(callMethod) { obj, error in
    print(obj)
    print(error)
}