I am using a UIWebView in my app and I am overriding the shouldStartLoadWithRequest message to detect what kind of link is being clicked. If it's a "special" link, I push a UIViewController onto the stack and return NO from this method. This works just dandy most of the time.
Sometimes, however, I click on a link and my shouldStartLoadWithRequest never gets called. Now what's weird is that the UIViewController which houses the UIWebView is in a UITabBarController and when I click on another tab, the UIWebView finally gets its shouldStartLoadWithRequest called. Until I click this other tab, I do NOT get a call to shouldStartLoadWithRequest. The other interesting bit is that the failure case never happens the first time I click on a link; it's always on a subsequent time.
Has anyone seen this? To me, this sounds like the UIWebView is, sometimes, not getting a touchEnded event and by switching tabs, the underlying framework is forcing a touchEnded event which in turn causes my shouldStartLoadWithRequest to get called.
Are you implementing the
– webView:didFailLoadWithError:
method from the UIWebViewDelegate? Perhaps you're getting an error on the request and then you're never seeing it? This delegate should get thrown when you have issue such as timeouts and other things.
Related
I have a UIWebView in my view controller and have set its delegate to the view controller via code (i.e. not through IB). I have also setup the appropriate delegate methods: shouldStartLoadWithRequest, webViewDidStartLoad, webViewDidFinishLoad and didFailLoadWithError.
In my view controller's viewDidLoad method I load an appropriate URL with this code:
[self.webView loadRequest:reqURL];
95% of the time everything works great and the page loads in the UIWebView object and displays as expected. Occasionally, however, the page doesn't load.
After stepping through my code I realized that on the times that it doesn't work the shouldStartLoadWithRequest delegate method fires, but webViewDidStartLoad doesn't.
Does anyone have any idea what's going on here? I couldn't find anything on Stack Overflow that specifically addressed this unique issue I'm having and am slowly reaching my breaking point. Thanks in advance!
You should make sure that your shouldStartLoadWithRequest implementation returns YES for all conditions at which you need your webView to load.
In my project I show an Alert to the user to indicate an 'empty list'.
Right now, I show it in AppDelegate>applicationDidBecomeActive.
I'm doing this because I want the alert to show if the list is empty
at app startup and when coming out of the background (iOS 4.2 through 5.x).
EDIT:
I use a method in the AppDelegate, and call it with a slight delay, and I still get this notice.
[self performSelector:#selector(checkForNoMessages) withObject:nil afterDelay:1.0];
However, this causes a "wait_fences" notice in the debugger and I'd prefer not to submit to Apple with this notice.
Where is the proper place to put a popup Alert so that it appears:
1) At App startup
AND
2) When the App is coming out of the background?
Do I need the Alert in more than one place?
I recommend writing a method in your AppDelegate or better in your root view controller which shows the message. Maybe with some arguments, so you can reuse it but that's up to you.
If you are following the MVC architecture ask your model about existing entries and trigger the Alert message if necessary. But encapsulate this behavior in a controller as well.
application:didFinishLaunchingWithOptions: and applicationDidBecomeActive: are the places where you want to delegate this task to your controller.
More about iOS Multitasking: https://developer.apple.com/library/ios/#documentation/iphone/conceptual/iphoneosprogrammingguide/ManagingYourApplicationsFlow/ManagingYourApplicationsFlow.html
Edit:
Don't forget that you have to call the methods from the main thread.
And do all startup stuff first.
OK - the problem wasn't where I called the alert, it was because it was in a method. Once I moved the code from a method into applicationDidBecomeActive, all is well.
I'm attempting create a spinning reload button, such as the one found in the new Path app.
It's for a UIWebView, and should behave in the following way:
upon touchupinside, it should reload the webview and spin while it reloads.
while it's spinning, another touchupinside should stop the reloading of the webview.
upon completion of the reload, it should stop spinning
it should be a subview of UINagivationController
Can a kind individual point me in the right direction or link me to a tutorial on something like this? I've searched around and there doesn't seem to be anything similar. Thanks!
The UIActivityIndicator class will give you the functionality you need. Use startAnimating and stopAnimating along with hidesWhenStopped. Documentation is here: http://developer.apple.com/library/IOs/#documentation/UIKit/Reference/UIActivityIndicatorView_Class/Reference/UIActivityIndicatorView.html
To use this with your UIWebView, you can place the calls to the UIActivityIndicator in the UIWebViewDelegate methods.
In webView:shouldStartLoadWithRequest:navigationType: you should return YES, and start the activity indicator. In didFailLoad and didFinishLoad you can then stop the activity indicator.
Finally, for your touchUpInside behaviour, you can send the following messages to your UIWebView, reload and stopLoading.
An alternative would be to call the UIActivityIndicator's methods at the same time as calling reload and stopLoading.
I have an application that uses UIWebViews in several view controllers. The UIWebViews are used to render locally generated html, no slow network access required.
To save memory I only load these on demand as prompted by the viewcontroller viewWillAppear callback. (And unload offscreen instances in response to didReceiveMemoryWarning messages.)
The problem is that the user gets to see the html being rendered, sometimes accompanied by flashes of styling and other assorted unpleasant artifacts. I would much rather the rendering be done offscreen, and reveal the fully rendered view when its ready.
It would be very tidy to be able to have the viewWillAppear not return until the UIWebView is fully rendered. But how?
I tell the UIWebView what to render by sending it a loadHTMLString:baseURL: message. This is asynchronous, and some time (soon) later the webview's delegate gets called back webViewDidFinishLoad.
I experimented with running a runloop inside viewWillAppear, running either the NSDefaultRunLoopMode or UITrackingRunLoopMode. This works in the simulator (it complains to the log
[CATransaction synchronize] called within transaction
but does work) but on a device it deadlocks, with webViewDidFinishLoad never being called.
(Also, it seems like the UIWebView loading property doesn't work. At least, after I call loadHTMLString:baseURL: and before getting the callback it's not true.)
Lots of solutions here I think. A quick one is to load your UIWebView with it's hidden property set to YES. Then set your UIViewController as the UIWebViews delegate and implement:
- (void)webViewDidFinishLoad:(UIWebView *)webView
where you set the property back to NO.
A thing to note is that webViewDidFinishLoad will fire more than once if you have framed/embedded content. So you have to keep track of this. Shouldn't really be a problem if you are loading local content.
I like monowerker's solution best, but another solution would be to hold onto the already-rendered UIWebView all the time (in some more permanent object than the view controller). I'd only do that if the look of monowerker's solution is too disruptive.
I can't find any documentation to confirm this, but it appears that you can only call the method stringByEvaluatingJavaScriptFromString in overridden methods from a UIWebView delegate. Can anyone confirm this?
Here's what I've tried. I setup a button on a view, link it to a method on my viewcontroller, and make sure it works fine. My view has a UIWebView control on it as well. If I run the project on the simulator or on the iPhone, there are no issues. Then I add this code to the button's method.
[theWebView stringByEvaluatingJavaScriptFromString:#"alert('Hi there!');"];
When I run the project, I can click the button and see the 'Hi there' prompt and I can click OK to dismiss it. Usually 4-5 seconds later the simulator crashes. I occasionally see the "__TERMINATING_DUE_TO_UNCAUGHT_EXCEPTION__" error, but not consistently; sometimes there's no error. It also doesn't always crash the first time. Sometimes I go to another page, and then try it again, and it crashes.
If I put the same code in the webPageDidFinishLoad event it works fine. But I'd like the code to be called when the user demands it so that event doesn't suit my needs.
I'm open to a workaround if you have any ideas? Thanks in advance!
I still don't know the exact reason this didn't work, but I found I could rewrite my code to get called during the UIWebView delegate methods instead.