UPDATED 2009-04-30: WARNING: this method will not always give the correct result. +[NSURL URLWithString:] requires it’s argument to have unicode characters %-escaped UTF8. But stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding will convert # to %23, so http://example.com/index.html#s1 would become http://example.com/index.html%23s1. Unfortunately, the two URLs are not equivalent. The un-%-escaped one refers to section #s1 in the file index.html, and the other tries to fetch the file index.html#s1 (“index dot html#s1”). I have not yet implemented a workaround, although I suspect one is possible, by building the NSURL out of bits of the JavaScript location object, rather then trying to convert the whole string.
UIWebView/WebView does not provide a way to find the URL of the webpage it is showing. But there’s a simple (and neat) way to get it using embedded JavaScript.
- (NSString *)stringByEvaluatingJavaScriptFromString:(NSString *)script
Is a deceptively powerful method that can execute dynamically constructed JavaScript, and lets you embed JavaScript snippets in Cocoa programs. We can use it to embed one line of JavaScript to ask a UIWebView for the URL it’s showing.
@interface UIWebView (CurrentURLInfo) - (NSURL*) locationURL; @end
@implementation UIWebView (CurrentURLInfo) - (NSURL*) locationURL; { NSString *rawLocationString = [self stringByEvaluatingJavaScriptFromString:@"location.href;"]; if(!rawLocationString) return nil; //URLWithString: needs percent escapes added or it will fail with, eg. a file:// URL with spaces or any URL with unicode. locationString = [locationString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]; return [NSURL URLWithString:locationString] } @end
With the CurrentURLInfo category, you can do aWebView.locationURL to get the URL of the page a WebView is showing.
One last note, the
if(!rawLocationString) return nil;
special-case was only necessary, because [NSURL URLWithString:nil] throws an exception (rdar://6810626). But Apple has decided that this is correct behavior.
Wow!This could be used with UIWebView classes in finding the Url’s of the web pages,its very useful.Nice post.
Comment by Jim Eric — April 23, 2009 @ 1:53 pm
Very clever! Using this method in an app. Just a heads up, you mixed up the use of “rawLocationString” and “locationString” in the locationURL method. You also forgot a semicolon after the return at the end. Seriously, really clever method of getting the current URL
Comment by Hunter Bridges — October 23, 2010 @ 3:19 pm
Thanks for these information,also I want to ask something,what is your wordpress blog theme name ?I really like it…
Comment by Prefabrik — February 17, 2011 @ 2:15 pm
Thank you :-), it’s actually just the old WordPress Classic theme, with little tweaks over the years. I wish I could be more helpful than that, but that’s really all there is to it, and unfortunately it’s not really clean enough to share (I’ve had it break a few times during upgrades).
Comment by Vincent Gable — February 17, 2011 @ 3:17 pm
clever hack :) stringByEvaluatingJavaScriptFromString is magic
Comment by Nur Nachman Eytan — November 3, 2011 @ 12:20 pm