March 2013
Intermediate to advanced
1000 pages
34h 51m
English
Content preview from Programming iOS 6, 3rd EditionBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Communicating with a Web View
Having loaded a web view with content, you don’t so much configure or command the web view as communicate with it. There are two modes of communication with a web view and its content:
- Load requests
When a web view is asked to load content, possibly because the user has tapped a link within it, its delegate is sent the message
webView:shouldStartLoadWithRequest:navigationType:. This is your opportunity to interfere with the web view’s loading behavior; if you return NO, the content won’t load.The second argument is an NSURLRequest, whose
URLproperty you can analyze (very easily, because it’s an NSURL). The third argument is a constant describing the type of navigation involved, whose value will be one of the following:-
UIWebViewNavigationTypeLinkClicked -
UIWebViewNavigationTypeFormSubmitted -
UIWebViewNavigationTypeBackForward -
UIWebViewNavigationTypeReload -
UIWebViewNavigationTypeFormResubmitted -
UIWebViewNavigationTypeOther(includes loading the web view with content initially)
-
- JavaScript execution
-
You can speak JavaScript to a web view’s content by sending it the
stringByEvaluatingJavaScriptFromString:message. Thus you can enquire as to the nature and details of that content, and you can alter the content dynamically.
The TidBITS News app uses webView:shouldStartLoadWithRequest:navigationType: to distinguish between the user tapping an ordinary link and tapping the Listen button (shown in Figure 24-2). The onclick script for the <a> tag surrounding ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.