I was running my iphone app, optimizing to reduce memory footprint etc. I see that the live byte shows around 3.5 - 4 MB.
I was wondering what is an acceptable value. Put other way, what is the ceiling I should try to stay under.
Related thoughts, at what level do I get memory warnings, like level 1 level 2 memory warnings?
I am guessing this will have a direct correlation to my iphone device. Is there a matrix we can build depending on the device. I am using iphone 3G
thanks a ton
mb
if you stay under 20MB you should be fine, but as always the less you use the better ;-).
as far as I know the it isn't documented when the memory warnings are triggered, probably because that it is implementation detail and it can change at any moment.
Anyway you shouldn't focus too much on numbers (you don't know other memory consuming processes (safari caching pages, apps in the background using memory), just be a good ios-citizen, make sure you don't leak memory all over the place and your app will be working like a charm.
Related
I am making an app that uses a lot of fairly big image files. I notice it crashes when they all get loaded on my iPhone 3G (128 mb ram), but not when I test it on a 3rd gen iPod (256 mb ram). So I assume there must be some percentage that is allowed for each app to use? My app has about 30 images at about 440k each loaded so 13.2mb. I didn't think that would be too much. They need to be swapped in and out pretty quickly, so releasing the ones not in use from memory doesn't seem like a good idea...
EDIT:
The app swaps images based on the way the phone is being tilted. It's 30 images from a 3D scene, so when you move it, it changes the perspective. It needs to be as smooth as possible.
The answer is: as much as you want, until the OS complains.
There is no such thing as an absolute memory limit, since it wholly depends on the phone's memory, how much the OS and its related services are taking up, and the time of the month (just kidding, but you get the idea).
You should be scaling down these large image files to fit into memory, or even more so, not loading them all at once considering the screen is so small and only so much can be viewed at any one particular time.
What is the amount of memory an app can take before getting kicked by iOS?
Does the amount of memory depends on the device version?
I have developed an app which is using 30+ mb and its getting kicked on iPhone 2g. Can it work on iPhone 4 or 3GS?
My experience with the iPhone 3G is that you should try to stay as small as humanly possible--build your data model with ditchability in mind, because you'll need to ditch. 20mb is bumping against the limit. 25 MIGHT be okay if the phone has been rebooted recently. You'll probably never get 30mb.
By contrast... I managed to prompt a memory warning on my iPhone 4 once, but it was due to an infinite loop bug that downloaded the same image file an infinite number of times. In other words, it took something REALLY drastic to crush the 4. Not that you can ignore memory management completely (a leak is still a leak), but for sure you've got some breathing room.
The 3Gs is somewhere between the two. I don't have one to test on, but I'd expect its performace is more 4-like than 3G-like, because while the on-board memory doubled from the 3G, the OS is still taking up the same space, meaning all of the new memory is yours to play with.
All your application's resources on an iPhone 2 should probably stay at less than 20 MB. You can go a little over, but that's it, otherwise the memory warnings will occur. There's only 128 MB of total physical ram for everything - that's the OS as well as your own app.
My iPhone app generally uses under 5MB of living memory and even in the most extreme conditions stays under 8MB. The iPhone 2G has 128MB of RAM and from what I've read an app should only expect to have 20-30MB to use.
Given that I never expect to get anywhere near the memory limit, do I need to care about memory warnings and setting objects to nil in viewDidUnload:? The only way I see my app getting memory warnings is if something else on the phone is screwing with the memory, in which case the entire phone would be acting silly. I built my app without ever using viewDidUnload:, so there's more than a hundred classes that I'd need to inspect and add code to if I did need to implement it.
Yes, please free all memory that you don't use!
Behaviours like this are one of the reasons Apple doesn't allow multiple Apps to run at the same time. Now imagine sometimes they will and all programs would be written like this...
How much real memory should my iphone app be using? What's going too high?
Keeping an eye on -(void)applicationDidReceiveMemoryWarning:(UIApplication *)application is definitely important, but if this is game, chances are the assets (notably textures presently on screen) can't simply be deallocated when that warning is received.
If you're a bit on the high side (20 MB +) I would recommend doing a bit of testing. Using Instruments and the Object Allocation tool (Run > Run with Performance Tool > Object Allocations) you can monitor how large your memory footprint gets. Then, try running Safari and fill the pages, then a few games and whatever else you can to get the memory higher, and see how your app performs.
In my testing for a recent release, 24 MB seemed to be pretty safe, and is a number I've heard elsewhere. Once you get above 30 or so MB, chances are your users will start having rare crashes (which happens to be the case for us, verified by crash reports). The higher you go, the more crashes users will see. There's no specific limit though, for the sake of testing I've pushed my app on an iPhone 3G up to 70 MB before, it just isn't likely to work for most, nor for long.
Requesting on the iTunes page that users restart their devices can help, though there's no guarantees it'll be effective.
Also, this is all assuming devices prior to the 3GS / 3rd Gen iPod Touch. If the app merely runs on an older device, it should have no problem on the newer ones (which have twice as much ram, 256 MB).
I think available memory may depend on several factors such as device model, how long it has not been rebooted etc.
You should not rely on some fixed values but instead try to use as little memory as possible and implement -(void)applicationDidReceiveMemoryWarning:(UIApplication *)application in your application delegate and/or -didReceiveMemoryWarning in your view controllers to handle low memory warnings there and free unused memory.
I know this is a subjective question. As far as I know, there are somewhat about 25 MB available for the app, but it depends on what else is going on. Currently playing music, a current phone call or what ever might drop that amount of memory down a lot. I don't know.
Just tell us what you think, or what you have experienced. My app currently consumes about 15 MB at a time, mostly lots of images loaded into views for animation. I have encountered no problems with this. But is there some "border" that can be drawn, to make a simple-to-follow rule like "do not consume more than x MB of memory at any given time", where x stands for the max amount?
This value highly varies per device and per user. For example, I restart my phone every few days, freeing up lost memory claimed by Apple and 3rd party leaks. My mother, has not restarted her phone ever on her own. EVER. She has tons of trouble with apps, gives me a call and I tell her to restart the phone to increase the ram. She does and the apps dont crash anymore.
Moral of the story is: Never plan on having available memory. You should always keep your memory down to the bare minimum you need at any given time.
You can use Instruments and launch some apps and find out for yourself.
Recently I found this awesome tool to find what is the maximum memory capacity of any iOS device.
We can also find at which memory level we received the Low Memory warning.
here is the link: https://github.com/Split82/iOSMemoryBudgetTest