I've posted about this before but have been struggling to come up with a solution.
Basically I have a HTML5/jQuery app within my iPad app. Every time I load an image into the UIWebView (HTML App) the overall allocations in the profiler increases by about 2MB each time. This sounds about right because the image is approx 2MB's. I am using the data notation in the tag to load a Base64 image.
i.e.
When I load a certain number of images (page turns) the app will crash.
The app is an ebook viewer, so when I turn to a new (not previously loaded in current session) the allocations increase. But, if I turn back to a previiously loaded page the allocations don't increase and the page loads quicker than a new one. Every page turn sends a request to the database so i'm beginning to think the leak isn't in the iOS and that it could be in the HTML5 app.
Any ideas on this? I guess there could just as easily be a leak in the HTML app as there could be in iOS. How do I go about debugging this?
Any ideas greatly appreciated.
Thanks
HTTP and WebKit likes to keep a local copy of resources, just in case you will need it again. This may be what you encounter.
Check the answers to this question: Is it possible to prevent an NSURLRequest from caching data or remove cached data following a request?
This was die an unfixable issue with iOS 4.
Issue resolved itself after upgrading to iOS5.
Related
I've added some video app previews for my app on App Store Connect and when I set the video poster frame, it never saves the image that I want, it always reverts back to the one that Apple defaults to initially. Does anyone know a work around?
UPDATE: I did get in contact with App Store Connect and they told me it's a recent bug that they're actively working on fixing. I'm going to touch base with them early next week.
Issue is still happening. But if you want to be able to upload without problems try this:
Upload the screenshots of one complete language
Don't touch anything for 2-4 min once pictures are uploaded.
Then you can refresh the webpage and check if the screenshots are well uploaded.
I have a component which consists of a FlatList and a Modal-component. This modal component has several Image-components. The images are set by the source-attribute to an external url.
I switch die visibility of the modal-component by changing the visible attribute.
The problem:
Everytime I open the modal (at the beginning or after closing it) the images are loaded from the server. So there are no images for maybe 1 second.
Are the images deleted from the cache if I set the visible of the modal to false??
Caching of images can be related to multiple things. The most effective one is probably the Cache-Control header sent from the server when you request the image. You can check the headers to see if the request has a low time on cache.
The other thing is that, while development process, building or hot-reloading of the app can result in clearing the cache for the app.
Another reason can be the low storage in device might be triggering the OS to delete cached images.
In iOS you can control caching. More info can be find here.
Its hard to tell without any sample code but, if you are mounting and then unmounting Modal when you set the visibility of it, you can try to prefetch images before mounting the Modal. If the caching control is right when you mount the Modal they should be served from the cache. If the images you are trying to show are large it might be a performance issue or they might be taking long time to load from the disk. You can debug this with a less number of item in modal with smaller images.
Hope the information above is going to be enough.
you can use react-native-img-cache
or react-native-cached-image to cash your images
and yes the images in react native are not cached by default
also to preload images you can use react-native-fast-image
I'm building a Windows Phone application that does video capture in a page and has a custom player in another page. I'm using my own custom codec so the player needs a lot of DispatcherTimer to keep track of several behaviors on the UI part and serve the movie at the good framerate in the codec part.
I'm trying to release all DispatcherTimer as I know they are CPU intensive, but even when stopping them my app is still very slow. If I press back-back then follow the flow, the speed divides by two each time. If I don't use my player, eveything is ok. And my player is only made of 3 DispatcherTimer, a FileStream and an Image box.
I feel that DispatcherTimer are still running in memory and are double-instantiated even if they are instantiated as private on the page directly.
Can I force the page to release all this stuff?
Actually I don't understand yet what is the difference between navigating to a page next to current page, or navigating back. I don't know i.e. how the page is shown again without calling InitializeComponents, so I'm mixed up about which resources to release, and which resources to keep intact.
My execution speed problem was really caused by some running DispatcherTimer, so I'll answer it to have it archived.
The solution:
Ensuring that all DispatcherTimer has been instantiated directly on the page so that we can nullify them from anywhere in the code.
In OnNavigatedFrom, I kill the DispatcherTimer and in OnNavigatedTo, I recreate them with myDispatcherX = new DispatcherTimer();
No "temporary" timers, like "DispatcherTimer myTempTimer = new DispatcherTimer; with ((DispatcherTimer)send).Stop() in callback, as chances are that it remains in memory in an application where we navigate.
strong textI am new to Sencha and I am evaluating it.
Every time I try to open a browser and visit the API page at docs.sencha.com/whatever ... it takes forever to load up.
I mean, what the hell is it doing at the back end? Is it taking that long to load up all the necessary extjs app files? Or is it loading me the whole API library while I am only try to see one page?
So far, I have gone through a couple of examples, and I like Sencha a lot . However, I have a concern about the loading speed in production, because the speed they load up the API scares me.
If you are experienced with Sencha, could you tell me what is going on at the back? Please don't say "API is 20MB big, takes time to load ...", because I only want to see one page per visit, i believe it is wrong to load me the whole API to initialize a page.
UPDATE ------------------------------------
I face this loading screen for 20-30 seconds everytime when I open the browser. IE only. Chrome and FF are fast??
UPDATE 2 ----------------------------------
I did a profiling for IE. Btween http://projects.sencha.com/auth/session?... and /architect/2guides/intro/README.js?... IE went to sleep for over 20 seconds blank doing nothing (as u can see from the highlighted blank gap in between the 2 rows in the picture), then suddenly came back and finish loading the rest of the page!
I copied those links 1 by 1 and load them up in a new IE window. They all individually came up in milliseconds, so there is no speed issue. It is just that, IE went to sleep for 20+ seconds (CPU monitor shows no activity) StranGe!
Since you're starting up, you should definitely start building your application using sencha cmd. This allows you to build a version of the extjs file that uses only the components that you use.
But as a side note. I use the full sencha api and it takes me less than 2 sec to load the whole API. I use the production version ext-all.js and ext-all.css and gzip everything. After the zipping, I get a file size of less than 500KB, which is like nothing actually.
EDIT:
I checked the API docs page. The total download size is less than 1 MB and that too cause there are a lot of icons which aren't combined as sprites. Hence the browser takes a lot of time in requesting the icons. That's why the page is slow.
For IE, well sencha can't do much about it. The browser itself is slow. Any webpage you load will suffer from the same problem. Not just sencha's. The page speed will improve if you do some optimizations. The size of the API isn't the problem.
I need a UIWebView to show a html page. if internet is not available it will show the last downloaded version. if has internet then it downloads the most current version and replaces and shows the version just downloaded. how can I do this? Thanks
You could implement you webViews delegate webViewDidFinishLoad: method to grab the request and load it again. Since it was just finished loading, we can assume that it is cached and load it with synchronous networking. Store the result. When network is unavailable load that result into the webView using loadData:MIMEType:textEncodingName:baseURL:. When network comes available agin just call loadRequest: to refresh.
Another option is to use stringByEvaluatingJavaScriptFromString: with a javascript around:
document.getElementsByTagName('html')[0].outerHTML;
and inserting the content with loadHTMLString:baseURL:
But these two only work for pure HTML without images, sounds, etc.
A third option would be to use the NSURLRequestReturnCacheDataDontLoad when network is not available. see NSURLRequest
You migth also have a look at the NSURLCache