I have a problem with using UIWebViews in an objective-C app we're developing. It crashes any Retina iPad. Both iPad 1 and 2 behave fine.
The web view is loaded from local HTML/CSS/JS and is dynamic content that contains pricing information so needs to be essentially a mirror of a website which is pre-downloaded to the device.
The page contains lots of images so I think this is memory related. I've tried reducing the payload on the page which stops the crashes. Obviously the stupidity of Apple to choose to quadruple resolution whilst only doubling memory is a root cause of why it works fine on non-retina devices, but how can I manage memory within the page to prevent iOS from destroying the entire app?
Does iOS automatically store imagery as 2048x1536x32bpp as a bitmap (theoretically 12MB per image?) irrespective of the file format? I've tried converting to JPG / PNG but with no effect on the crashes. Only reducing the volume of images present on the page stops the crashes. It's my first foray into iOS development, so please be gentle!
iOS won't change the resolution of the original images that the page loads, but of course it will de-serialize them from .png/.jpg to a bitmap in memory for display, so you should start by trying to reduce the resolution of the .png/.jpg images that the page loads.
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I'm very new to objective C, that's actually my first app...
I'm working on an application which has a list of projects, each project has its own gallery of images, segues וarc. the gallery takes about 90% of the screen, and a row of thumbnail takes the rest.
It is running OK on the simulator, but when I get out of one gallery to another (somtimes after three or four passages) the application crashes (on real device - iPad2 with IOS 6).
There is no exception or error, the log is clean. It seems to crash when the application reaches 350MB of RAM.
I believe there is no memory release between passing trough the galleries, even though I am usingבarc וsegues.
In addition, on the first entry to each gallery, it takes a few seconds for the gallery to load (only on first run, if I exit and reenter the same gallery it enters immidiatly) which seems further clue that it is kept in the memory.
I would really appriciate any idea, even if it simple as this is a first app and I'm not very experienced.
Thanks for your time and help...
I am not sure the exact reason for this is the memory issue. but when you handling the big payload(data) on your project,you have to think about what happen the memory reach the maximum reachable data size allocate for the app at the time.
Thanx for the API you have a call back method when fires the app reach the maximum Data size the system can handle.
- (void)didReceiveMemoryWarning{
// in this metod you can remove(release) additional memory used by your view controller
// in your case UIImage objects of the gallery.
}
You can't call this method directly. it's a system call method.
but you have a option to ask to call method, when you debug in the simulator.
(Simulator Status Bar: -- Hardware > Simulate Memory Warning).
documentation here
I just spent a day trying to figure out why some simple code was not loading images from the resources folder. Just for kicks I went into the finder and renamed one of the files to exactly the same name and it loaded. Then I did the others - simply renaming them to the same name. I looked and there weren't any strange characters or whitespace before or after the file name. So now they all load fine into an array in the simulator. But now on my device, they aren't loaded into the array, returning "nil" and are throwing exceptions. I know that ios devices are case sensitive where the sim is not but I checked this and the naming is all fine. The only thing I can think of is that my images are named for retina (#2x~iphone) and my device is not. But I have images named the same way, for retina, and those load fine.
I am using imageWithContentsOfFile to load the images and also getting a memory warning after it tries to load the images. I am not sure if the memory warning is related.
I think the problem might be in your file naming. Remember that you should include both retina and non-retina graphics in your app. Seeing as you added "~iphone" I'm assuming this is a universal application so your images should be named as follows:
myImage~iphone.png
myImage#2x~iphone.png
myImage~ipad.png
myImage#2x~ipad.png
Then in your code you only reference the "myImage" part of the file name so iOS can sort the rest out for you.
For example:
UIImage *image = [UIImage imageNamed:#"myImage"];
I am about to launch a new app and would lik eto increase quality of the graphics. In my case the graphics is the logo and the custom buttons. I do not know if this impact Core Plot but that is also part of the package.
There is quite a few posts about this but there are still things i do not fully understand.
I am reading this quote from "amattn":
It's trivial:
1.Only include #2x images in your project.
2.Make sure those images have the #2x suffix.
The system will automatically downscale for non-retina devices.
The only exception is if you are doing manual, low level Core Graphics drawing.
You need to adjust the scale if so. 99.9% though, you don't have to worry about this.
From this post: Automatic resizing for 'non-retina' image versions
My question in regards to this is:
1. Should i do the testing on retina simulator only, as if i place a #2 grapic on
non-retina it will be too big? ...or is there an other way of doing it?
2. Should i always use a ImageView or is it OK to drag the image on the screen,
this is the logo i am talking about?
3. What about custom made buttons with images, how should i do with those?
4. What is the normal process to manage the different screen sizes, do people
add images for all displays or using this type of process?
Should i do the testing on retina simulator only, as if i place a #2 grapic on non-retina it will be too big? ...or is there an other
way of doing it?
It doesn't really matter which simulator you test on because as long as your non-retina and retina graphics are named correctly (image and image#2x) the correct image will be displayed automatically.
Should i always use a ImageView or is it OK to drag the image on the screen, this is the logo i am talking about?
When you drag and image from the project directly onto a view in interface builder you don't really see it happen but it has automatically created and image view which is containing the image your dropped in.
What about custom made buttons with images, how should i do with those?
[myButton setImage:[UIImage imageNamed:#"myFileName"]];
As shown in the above code you should always use the non-retina fle name when you reference the image a UI element should use. That was if iOS detects the device is retina it can automatically use the #2x version in its place.
What is the normal process to manage the different screen sizes, do people add images for all displays or using this type of process?
Yes, including multiple image resolutions common practice and is required for iPhone apps (not sure about iPad) to include both retina and non-retina images. But regardless of the requirements, you should definitely support both device resolutions to keep your customers happy!
I am developing a cocos2d game. I need to make it universal. Problem is that I want to use minimun amount of images to keep the universal binary as small as possible. Is there any possibility that I can use same images I am using for iphone, retina and iPad somehow? If yes, how can I do that? What image size and quality should it be? Any suggestion?
Thanks and Best regards
As for suggestions: provide HD resolution images for Retina devices and iPad, provide SD resolution images for non-Retina devices. Don't think about an all-in-one solution - there isn't one that's acceptable.
Don't upscale SD images to HD resolution on Retina devices or iPad. It won't look any better.
Don't downscale HD images for non-Retina devices. Your textures will still use 4x the memory on devices that have half or even a quarter of the memory available. In addition, downscaling images is bad for performance because it has to be done by the CPU on older devices. While you could downscale the image and save the downscaled texture, it adds a lot more complexity to your code and will increase the loading time.
There's not a single right answer to this question. One way to do it is to create images that are larger than you need and then scale them down. If the images don't have a lot of fine detail, that should work pretty well. As an example, this is the reason that you submit a 512x512 pixel image of your app icon along with your app to the App Store. Apple never displays the image at that size, but uses it to create a variety of smaller sizes for display in the App Store.
Another approach is to use vector images, which you can draw perfectly at any size that you need. Unfortunately, the only vector format that I can think of that's supported in iOS is PDF.
I want show per page pdf in portait mode and display two pages when rotate to landscape mode on ipad . I had search on internet and can't find any solution. I thought two possible way.
1.Using webview but I don't know how to display two page in one webview in a webview.
2.Using CGPDF API read from two page and merge to one pdf file. But I think this may be very slow and not sure if this could do it .
or any other way could solve this problem? Thanks!!
I don't think you will have much success with using a UIWebView there. There's however nothing stopping you from putting two CATiledLayers into a UIView and display them next to each other. In fact, that's exactly what I did in my iOS PDF parsing framework.
Just set the contentView as the containerView, that includes both tiled layers, and they work perfectly together. Keep an eye on your memory though, I wouldn't allow them both rendering pdf at the same time, that most likely crashes your app due to low memory. (Drawing a PDF is really resource intensive)