Question

Say, I have an address bar which is a UITextField called textField, and a UIWebView named webView. Most of the time the follow code works:

[webView loadURL:[NSURL URLWithString:textField.text]];

When I put in some long string with special characters, URLWithString: simply returns null. The Readability bookmarklet is a good example:

javascript:(function(){readConvertLinksToFootnotes=true;readStyle='style-newspaper';readSize='size-medium';readMargin='margin-wide';_readability_script=document.createElement('script');_readability_script.type='text/javascript';_readability_script.src='http://lab.arc90.com/experiments/readability/js/readability.js?x='+(Math.random());document.documentElement.appendChild(_readability_script);_readability_css=document.createElement('link');_readability_css.rel='stylesheet';_readability_css.href='http://lab.arc90.com/experiments/readability/css/readability.css';_readability_css.type='text/css';_readability_css.media='all';document.documentElement.appendChild(_readability_css);_readability_print_css=document.createElement('link');_readability_print_css.rel='stylesheet';_readability_print_css.href='http://lab.arc90.com/experiments/readability/css/readability-print.css';_readability_print_css.media='print';_readability_print_css.type='text/css';document.getElementsByTagName('head')[0].appendChild(_readability_print_css);})();

According to this answer, I can use stringByAddingPercentEscapesUsingEncoding to escape the string, and indeed it works fine for this case.

My question is: Is this safe to always call stringByAddingPercentEscapesUsingEncoding: before passing the string to the webView? Does the following have any consequences?

[webView loadURL:[NSURL URLWithString:[textField.text stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]]]

Thanks!

EDIT: What I mean by ‘safe’ is that while this works with URLs containing Unicode characters, does it still work fine with ‘normal’ URLs?

EDIT 2: If this is ‘safe’, why isn’t it the default behaviour?

Answer 1

Since there’s no other answers to my question, I decided to use the following - (NSURL *)URLValue method instead of - (NSURL *)URLWithString: as a safe measure:

- (NSURL *)URLValue {
    NSURL *URL = [NSURL URLWithString:self];

    if (URL) return URL;

    return [NSURL URLWithString:[self stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
}