UIWebView stringByEvaluatingJavaScriptFromString in background

Question

In an iOS app, I\'m running a fairly large script on a UIWebView using stringByEvaluatingJavaScriptFromString (large in terms of the length of the java

Answer 1

No, Webviews and the Webkit JavaScript engine are both single-threaded and cannot be used on a background thread.

A better option is to split up your JavaScript into discrete execution blocks and pipeline them using a JavaScript timer, like this (JS code, not Obj-C):

var i = 0;
var operation = function() {

    switch (i) {
    case 0:
       //do first part of code
       break;
    case 1:
       //do second part of code
       break;
    case 2:
       //do third part of code
       break;
    etc...
    }

    //prepare to execute next block
    i++;
    if (i < TOTAL_PARTS) {
        setTimeout(operation, 0);
    }
};
operation();

That will prevent your script from blocking user interaction while it executes