如何在iOS中将变量从JavaScript传递到目标C，将目标C传递给Javasctipt

Question

I am a iOS Developer, am new to javascript.

I wants to create a communication between Javascript to Objective C and Objective C to Javascript.

How to pass a variable from javascript to objective C and Objective C to Javasctipt in ios.

If any one have references please let us know about this?

Answer 1

I program JavaScript when using Parse CloudCode. In my case, I use CloudCode to call the Stripe API.

For example:

Objective-C

NSDictionary *parameters = @{
                                 @"customerId": stripeCustomerId,
                                 @"amount": @(100),      
                            };

[PFCloud callFunctionInBackground:@"chargeCustomer" withParameters:parameters block:block];

JavaScript

Parse.Cloud.define("chargeCustomer", function(request, response) {
  Stripe.Charges.create({
      amount: request.params.amount, // in cents
      currency: "usd",
      customer: request.params.customerId,
    },{
    success: function (httpResponse) {
        console.log(httpResponse);
        response.success(httpResponse);
    },
    error: function (httpResponse) {
        console.error(httpResponse.message);
        response.error(httpResponse.message);
    }
  });
});

As you can see, to pass on the variable from objective-c to javascript in this case, you use request.params.

Answer 2

You can use native iOS objects to do this.

From Obj-C to JS

- (NSString *)stringByEvaluatingJavaScriptFromString:(NSString *)script

It injects or calls pre-existing method/object in the page loaded in the UIWebview. It returns the value that JS return to you

UIWebView Class Reference

From JS to Obj-C

Implementing UIWebView protocol you can handle the request before it will start:

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest (NSURLRequest *)request navigationType (UIWebViewNavigationType)navigationType

So, from JS you have to call a URL with a custom schema http such as test:// . Then you will parse the request in the delegate method I wrote before.

Answer 3

If you are targeting iOS8, you could consider to use WKWebView rather than UIWebView , which has considerably improved in this regard. Good starting points are the the WKWebView reference docs and this NSHipster article .