iOS stringByEvaluatingJavaScriptFromString无法在简单代码中运行

Question

I wrote a piece of code about JS:

NSString *function1 = @"function getString(){return \"123\";}";
NSString *str = [theWebView stringByEvaluatingJavaScriptFromString:function1];
NSLog(@"str: %@", str);

but the "str" is not equal to "123", the result was

str: 

Any help is appreciated。

Answer 1

Your JavaScript code only defines the function getString , but never calls the function. Therefore the result of evaluating the script is empty.

If you actually call the function in the JavaScript

NSString *function1 = @"function getString() {return \"123\";} getString()";

you will get the expected result.

Answer 2

This method mosf often usage for running java scripts based on current page contents. You can see similar question Here

But I've found example with definition of java script here