I have created iPad application which downloads images using web service. But my application crashes somewhere during manipulating with high quality images. So my question is - what is max memory limit for application running on iPad? When does the application hit LowMemoryWarning on iPad?
There is no per-application limit so to say. The amount of memory available to an application depends on the amount of free memory, which again depends on the amount of memory used by applications running in the background. These apps include permanently running system apps like SpringBoard, sometimes running system apps like Safari, iPod, etc and (when iOS 4 will come for iPad) user-apps that still run in background.
Nevertheless, I'd say an app should never use more than 50% of all available ram. On iPad this currently means 128 MB and should be quite a lot. Did you do a leak check on your app?
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I want to develop one application which should be monitoring how much application is running on how much time on my I-Phone Device(including internet browsers).
Please share your idea regarding this post.
little similar like this:
https://itunes.apple.com/us/app/system-manager/id455736462?mt=8
thanks
You really can't since Apple has placed very restrictive guidelines on Apps for iOS.
Although with some low level call you might get some running process information.
Because of the sandbox environment you might not be abele to much more information then that.
Also app's in background are suspended if they have no background running flaggs (voip, audio, location or accessory). Also if the system gets low on memory app that are suspended get killed and there memory freed up.
What you can do:
Try the List of All Processes OS X code which
Can we retrieve the applications currently running in iPhone and iPad
But keep in mind the restiction placed on you app by Apple: The iOS Environment, thus that there are app availble in the appstore that do what you want does not mean that you app will be allowed.
I wrote an app compiled against ios 3 that would easily allocate up to 100 mb of memory for image processing purposes. However, when that same app was compiled against the ios 4 sdk, I found that it crashed when many apps were open in the background. When I kill the background apps, the application then runs fine. I reduced the memory usage to 70mb, and I still find that it crashes when many background apps are open.
Why are apps compiled against ios 3 are able to get more memory on phones running ios 4?? Is there something special you need to do to tell the ios 4 OS to give you more memory? Is there a way to cause background apps to be closed in order to allocate more memory for your app?
BTW, the app uses Core Graphics to some extent. Would that affect the apps ability to request memory?
Given your description, your app was pushing the memory allocation envelope on iOS 3.x, but goes too far in 4.x, likely because the newer operating system is using more memory.
The only solution is to use less memory. It really is that simple. You can't control how much memory the underlying OS will use to run processes. The only thing you can control is your app and how much memory you allocate so you don't crash.
It's unlikely that you "find that it crashes when many background apps are open". Almost certainly the system is terminating your app for using too much memory and ignoring any warnings to that effect. (I guess you could crash by trying to allocate more memory than the system has available, but that would have to be a very large allocation made in a large chunk).
Tell us more about how you're allocating this memory. Are you paying attention to low memory warnings?
I'm writing an iPad app that acts as a media player (video and photos). I know there is a 2GB size limit on apps, however is this the size limit on an app when downloaded? Or the limit on the size of your sandbox throughout the life of the app? For example what if my small app later on downloads various media files to its sandbox that put the user over 2GB total (app + downloaded media)?
Thanks!
There is no limit to the size of your sandbox other than the remaining capacity of the device itself.
I did a little test last night, and my sandbox was over 8 GB when I finally called it quits.
Sandbox size is unlimited, According to the iPhone Application Programming guide:
To manage program memory, iPhone OS uses essentially the same virtual memory system found in Mac OS X. In iPhone OS, each program still has its own virtual address space, but (unlike Mac OS X) its usable virtual memory is constrained by the amount of physical memory available. This is because iPhone OS does not write volatile pages to disk when memory gets full. Instead, the virtual memory system frees up volatile memory, as needed, to make sure the running application has the space it needs. It does this by removing memory pages that are not being used and that contain read-only contents, such as code pages. Such pages can always be loaded back into memory later if they are needed again.
If memory continues to be constrained, the system may also send notifications to the running applications, asking them to free up additional memory. All applications should respond to this notification and do their part to help relieve the memory pressure. For information on how to handle such notifications in your application, see “Observing Low-Memory Warnings.”
IIRC, Apple limits size of d/led applications to 20MB.
Can anyone link me to a page that describes memory allocations for iPhone apps.
I have heard that you are limited to a sandbox of ~20 megs, depending on the state of the phone, but I can't find the source for this.
It depends on the device you're using. I've found that with an iPhone 3G, when the total memory your app is using goes over 10-14MB, it's vulnerable to crashing. When it hits 20MB, it will crash for sure.
As far as I know, Apple doesn't give any hard figures for the memory that you can use. It's always changing so it's hard to pin down. They recommend that you rely on memory warnings and respond to them appropriately.
iPhone 3GS has a much higher amount of memory available to apps (I've heard that it's around 4 times). Although the iPhone 3GS only has double the memory of the iPhone 3G, a lot of that memory is taken up by the OS. There's very little left for apps to run in. That's why the 3GS will allow apps to use so much more memory.
Also, there can be a lot of memory already in use by the OS. One example is when safari is keeping a lot of tabs open. This is why lots of games recommend that you restart the device if it crashes a lot.
When you're programming, keep an eye on the increase of memory (due to not properly deallocating objects) and the peak memory. This problem is more about real-world testing (on as many devices as possible) and good programming practices.
Here's an article to ready more about how to deal with memory problems:
http://akosma.com/2009/01/28/10-iphone-memory-management-tips/
This tool finds what is the maximum memory capacity of any iOS device. It also can also find at which memory level you received the Low Memory warning.
here is the link: https://github.com/Split82/iOSMemoryBudgetTest
It depends on current device state. Some native iPhone applications can run in background and waste device resources(Mail, Safari, Sms, Phone...) So, it's hard to say how much memory u will get...Ideally, your application should stay within 10-12Mb limit to successfully overcome any memory issues.
I believe it's
Memory warnings at 20MB
Application "crashes" at 30MB
I'm fairly certain I saw this in The iPhone Developer's Cookbook: Building Applications with the iPhone SDK by Erica Sadun (amazing book, btw).
Also: Duplicate -> Maximum runtime memory available in iPhone and iPod?.
I'm developing a new application for the iphone.
I want to understand something - does the memory that my application uses shared with other applications?
What if an application causes memory leaks, does it effect the device performances after the user closes the application?
thanks.
At the moment, on iPhone you'll only be sharing memory with a certain few applications - MobilePhone, MobileMail, MobileMessaging, Safari, iPod and a few minor daemons.
If you're the active application and you need more memory than is free, then some of these applications (but not the most critical ones, like MobilePhone) will be terminated in order for you to continue. If you continue to use memory, you'll be terminated before the critical apps.
The amount of memory you can use depends on which device you're on and what else is going on on the device. Common advice is that as long as you stay under 30Mb, you'll be fine.
Once an application is terminated, the fact that it leaked memory (or not) is no longer an issue - the system will clean up and free it's entire address space.
Apps sometimes say that you should reboot your iPhone before running the app, clearing the RAM that critical daemons use for caching or whatever during normal use.
If you ever find yourself doing this, stop. If you ship an app with this requirement, you fail as a programmer and should be banned from programming. Why? Look up the amount of RAM a Playstation 2 has, then look at games like Gran Turismo and Grand Theft Auto.