I'm developing a game with lots of graphics for iOS platform. None of the graphics are dynamic, they're all ready made images. There are 6 layers on the screen and each layer contains 3-4 graphics objects in average that constantly scroll to left, each with different speeds. So with each screen refresh about 20-25 objects are scrolled, removed from screen and added again from right. The game is universal so images of all sizes present in the resources folder.On iPads, iPhone 5, iPhone 5s it goes smooth. But on 4th Gen iPod touch I notice some hiccup.
When I test the app with Instruments, I notice a critic memory problem at start and then the problem goes away. So this is all because I load all the above graphics on application start. All the images are combined into 4 different sprite sheets. So here's my question:
Is it the weight in kilobytes that matters or is it the dimensions? I'm asking this because I reduced the size of the images by about 70-80 percents, though their height and width remain the same, but that memory problem still exists.
If you are reducing the size of the images by utilizing compression, then expect there to be delay and a memory hit as the images are uncompressed when first loaded, and they will take up as much memory as they did before compression.
The 4th generation iPod Touch probably is having some memory pressures and it will try to release memory elsewhere in order to allow for your images to load up and stay in memory. That may be the hiccup you see, as other apps, like Mobile Safari or Mail are asked to give up some memory or to terminate.
(The size the images take in the resources folder is inconsequential. It is the size they take when they are uncompressed and in memory that matters).
You could make the images smaller by making them 4bit instead of 8bit color, or you could make them monochrome. You can also use a non-retina size or smaller, and then let the OS stretch them out to fit the space required. I would try to use the best images first, and if you get a memory warning (didReceiveMemoryWarning), then reload with the images that are less dense.
you can not load all image before the game beginning, you should use the cache to control the size of the memory. And before the scenery of game change ,the release the cache ,reload the need ones.
So you must control your resource dependents in the every game scenery.
This is the common method to management the large resource application.
Related
I would like to add a background image for iOS and I want the background image to have appropriate resolutions for all tablet and phone versions. What design considerations should I take into account? What resolution should the image be in?
This the list of current screen resolutions for the variety of devices: click for resolutions
You could create 10 different images, 5 each for the landscape and portrait views.
Alternatively, you could create 2 or 4 images to cater for the landscape and portrait views and use code to check the devices size to size them appropriately.
The advantages of creating all the right sized images means that you have a precise background that is consistent across all devices, especially if you have logo's in the background as distortion may occur with resizing of images across devices.
Conversely, creating only 2-4 images should reduce memory size as the app downloaded will only be packaged with those background images instead of 10, and if resized correctly, shouldn't look to out of place.
I would test the 2-4 images using simulator, checking the look and performance on all devices you plan to release to. If you aren't happy, either customise your layouts for the images so they stretch to fit appropriately, or, for symmetry across all devices, I would create all the images and package, with an attempt to reduce the size of each image to be perfectly aligned with the device boundaries to reduce memory consumption.
The disadvantage of using 10 different images is the extra code required to fit, and should a new device size come out, you will need to create additional images, which ultimately consumes more memory and requires long term monitoring. It also consumes unnecessary memory if you are using an iPhone 6 and have images for all the other devices.
My advice - weight up whether you really need the background and if so, whether or not resizing just 2 images to fit any device will impact the look of your app.
I know this is a stupid problem, but this is my first real app that I have to make, I have no one to ask and I looked up this problem and found no other similar problems.
My app crashes on real devices with no exception. I saw in the simulator that uses too much RAM and after a while I got to the conclusion that the pictures I am using are to blame.
The app is structured in this way: it has 8 viewControllers for different things: for example, it starts with one which lets the user select the avatar with which he/she will play and here I have two pictures, next is a viewController which shows the stats for that avatar and here it is another picture and so on. The problem is that each picture uses 40MB of RAM to be displayed and things add up so the app uses more than 300MB of RAM when the user gets to the gameviewCOntroller where the game is. Because of this, on devices like iPAD 2 or iphone 4 it crashes, but not on iphone 5.
I tried to set the images both from "images.xcassets" and from a ".atlas" folder, but the result is exactly the same. The pictures have a dimension of no more than 1500x1999px, they are in png format.
Also, I saw that if the app were to start directly into the gaveViewController it would use 180MB so the other viewController remain in memory or something like that. Should I "clear" them or something similar?
//-------update-------
This is what I got from Instruments:
Memory is a big deal on mobile devices, there is not a clear answer to you question, but I can give you some advices:
If your images are plain colors or have symmetric axes use resizable images. You can just use one line of pixel multiplied by with or height to cover the entire screen using a small amount of memory
Image compression doens't have effects when the image is decompressed. So if you have a png that is 600kb and you are thinking that converting in a 300kb will lower memory usage is only true for "disk space" when an image is decompressed in memory the size is widthXheightXNumber_of_channelXbit_for_channel
resize images: if are loading a 2000px square image into memory and you show it inside an image view of 800 px square, resize before adding it.You will have just a peak while resizing, but later it will use less memory
If you need to use big images, use tiling techniques such as CATiledLayer
If you don't need an image anymore get rid of it. It's ok to have an array of path to images, but not an array of full uncompressed images
Avoid -imageNamed it caches images and even if Apple says that this cache is released under memory pressure, you don't have a lot of control on it and it could be too late to avoid a crash
Those are general advices, it's up to you if they fit your requirements.
You should definitely follow Andrea's advices.
Additionally you should consider setting the image size to exactly what your need is. You're saying that you've tried to set them from xcassets so you have full control over the images you're loading, which is great (compared to downloading an image that you cannot modify).
I highly suggest you read some documentation on using Asset catalog files. This will allow you to have high-resolution image for bigger screens that also have more memory, and smaller ones for older devices, which is what you want here.
Also, note that 1500x1999px is still a very big size for most mobile devices.
More links about screen-size:
https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/MobileHIG/IconMatrix.html
http://www.paintcodeapp.com/news/iphone-6-screens-demystified
I have an app that has 12 images contained in an array. All these images are displayed at the same time on the screen. (1 view - 12 much wider and higher images (UIImageView's) one on another. When user does something, app moves the images, thus the view displays different scenes)
The images themselves are not too heavy (it is about 2500x5000 in size, but the whole folder with images is around 3.5 MB).
After loading, the app consumes 355 MB.
When I put breakpoint in viewDidLoad (and all images are loaded at that time), xcode shows that the app consumes only 9 MB, but in viewDidAppear it is 355 MB.
What is the reason of it? And how can I store images compactly? (As I assume that the problem is in the images).
Thank you for any help!
An image open will occupy something like : H x W x number of channel x number of bit for channel, the file size is another thing, because images are compressed according to their type. Your images are 50Mb each one in memory.
The only way is to resize the image before displaing them. There are plenty of image resizing categories online, just google a little bit.
The other suggestion is to not load all the images togheter, just bring in the array the file path, and instantiate the image lazily.
If you need to use hires images you should look for CATiledLayer and tiling techniques.
These images probably cannot be displayed all at the same time onscreen, so you may want to load them only when necessary.
If you still need to display them all together onscreen, think about reducing their size.
Still, 355Mb is huge. Are you doing anything else in that application, that might use up all of that memory?
In Xcode go to Product->Profile. You will find there a lot of useful instruments which will help you to find problems with memory, CPU or battery usage. However, check it if you haven't seen it before.
I Just started developing an Universal iOS app for which I need to set the Background image.
Instead of using 3~4 different size images for iPhone, iPhone-retina, iPhone5 , iPhone5-retina & iPad, iPad-retina , I Just want to take one Highest resolution Image (say 1024*780), Which I want to use to fit all the above mentioned devices. How???
self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"sfond-appz.png"]];
& it is not occupying the exact screen size for smaller devices. it is shrinking.
Please Advice!!!
If Apple suggests to use different images for each kind of display there is a specific reason, and that reason is memory.
As display size increases it increases also the memory available on the device that's because bigger images require more memory. Even if you want to resize (not stretching) them at runtime, the first time you open it will occupy that memory until you release it. The memory occupied it doesn't have to deal with the file size.
If you still want to try take a look at this library that will help you to resize (not stretch) images at runtime NYXImagesKit
I'm doing the same thing in one of my apps in the App Store. On the main menu view, I use a UIImaveView as the background and set the mode to Aspect Fit in Interface Builder. I use struts and springs to keep it aligned to the edges.
For a universal app, you'll create this UIImageView on both the iPhone and iPad story board (or .xib files) and use the same image file.
However, I still have a 2x version for retina displays. So, I use just two images to cover all devices, orientations, and resolutions.
It will consume less memory if you create a background image to fit each device, but you will obviously increase the bundle size. In my case, the goal was to keep the bundle size small (under 50 MB for cellular delivery), and I had memory to spare.
I'm working on an iOS app using PhoneGap. I ran into an annoying problem where some of my images weren't loading. Thinking it was a cache issue I played around swapping images.
I finally discovered that the issue had to do with the height of my image. After a whole bunch of trial and error I discovered that an image taller than 7864px will not load in the iPad simulator or the iPad itself. It will load fine in Safari. It's not a file size limitation as these are only 45k in size and I'm loading images that are 700k in size elsewhere without a problem.
Has anyone run into this? I can't find any documented restrictions on image dimensions within mobile Safari. If there are restrictions, knowing them would be handy.
For native apps, Apple says images larger than 2048x2048 1024x1024 are to be avoided and should be broken down into smaller ones. The problem here is not the file size on disk, but the size in memory: the image has to be decoded and turned into a "flat" representation.
So let's do some math: assume an image 5000x5000 pixels, with 8-bit RGB. This means each pixel occupies 3 bytes:
5,000 * 5,000 * 3 = 75,000,000 (roughly 71.5 MiB)
So you see your seemingly small image really fills up the memory very fast. iOS now cannot throw parts away if it's under memory pressure, it's the whole image or nothing.
Your only solution is break down the image into smaller parts. iOS can then remove images that aren't visible any more from memory (I doubt with such a huge image that all parts are visible all the time).