I have an app that can import images. My app doesn't need large images, so if I see an image larger than 512 pixels on a side, I resize it.
I'm using some image resizing functions that I borrowed from:
http://vocaro.com/trevor/blog/2009/10/12/resize-a-uiimage-the-right-way
The resizing functions work really well most of the time, but I have some large photos in my library that are 5616x3744. When I try to resize this image, it sometimes causes a crash while executing CGContextDrawImage() (about half the time it crashes, although once I was able to process about 20 images before it crashed). It is not consistent about which images it crashes on yet.
I haven't tried this in the simulator yet, but have been running on my iPad in develop mode while connected to the debugger. When the app crashes, it exits right out of the debugger and returns with signal "0".
I was wondering if there might be a memory issue, but when I run it with the allocations instrument, it doesn't go past about 44meg before crashing, and my app gets no memory warnings.
Is the resize operation just allocating a HUGE amount of memory that causes an out of memory crash without getting any kind of warning first?
I guess I could restrict my app to smaller images, but I would like to know why the crash is happening to make sure that it isn't something random that could bite me later.
Any help is greatly appreciated!
Thanks,
Ron
I've done a bit more debugging and I think what is happening is that the OS is killing my App for allocating too much memory. Since it is done in a single operation, the OS doesn't get a chance to notify my app about running out of memory, and just kills the app. Kind of sad that an iPad can't even resize a single 20 megapixel photo without being killed. Hopefully the iPad 3 will have at least 1gig of memory! My iPhone4 will do 70 megapixel photos without a problem.
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I have a universal app that is essentially a list of articles with images and text, and menu under the left side of the app. I have google analytics in, as well as parse's framework.
The only difference between the app on the iPad and iPhone is that the side menu is always visible on the ipad, and a few interface objects are moved around. (different cell layout for the list--same content, though).
The images are loaded asynchronously using a set of classes that I wrote to download/save in an NSCache object and on the disk using a NSOperationQueue. (disk cache is wiped when the user leaves the app). The NSCache is set to max out at roughly 10 mb. (assuming image size is image hight*image width * 4 bytes per image). (code here is identical for both, so it shouldn't be the culprit, but it is a large chunk of the apps memory use).
I was having some trouble with memory warnings/crashing on an older iphone4 running iOS 5.0, so I ran the app with the Activity Monitor Instrument, and noticed something very odd:
On the iPad (an iPad 2 running iOS 5.1) the app launched, loaded the images that were visible immediately, and was using about 16mb of memory.
On the iPhone4 it launched, loaded the visible images and was using about 35mb of memory--way more than I would expect.
In order to check if it was an OS memory issue, I also ran the app on an iPhone5 running iOS6 and it used about the same amount as the iPhone 4.
I checked my media and the storyboard files to see if anything was different at all, and I could not find anything that could change the memory usage in any significant way.
Is there any way to reduce the memory use of the app on the iphone? I can think of no reason it would use so much memory.
Very difficult to see.. as one person stated pay attention that retina devices will use more memory according to the source, if in the bundle you set #2x images it will load them, and they use more memory.
Have tried to profile the Virtual memory using allocations?
Using memory is usually fine even if it fires a memory warning, the problem is how you respond to it, when it comes does it free enough memory? try with the simulator to simulate a memory warning. Pay attention that sim uses more memory than device.
One other point is that since ARC is difficult to create leaks, but it's easier to create retain cycle and abandoned memory. A correct object life cycle should end with object deallocation.
You say that you use NSCache and load images from the net async, I've got 3 suggestion for you :
Do you know the original image size on the source? maybe on the iPad source images are smaller than on iPhone. A correct approach after you download an image will be resize it according to the really needed size (I'm mean redrawing non just stretching) you ca achieve that with Quartz or using ImageIO
I never understood the behaviour of NSCache after memory warning, Apple says that it will flush the memory but after some test on iOS4 (I don't know now) I don't agree. I've created my own subclass that observe for memory warning and flushes memory
Are you totally sure that you are getting back image from the cache ?
I am working on an iPhone game which receives memory warning that I am not experienced enough to interpret. I have been watching some iTunesU tutorial but I am still not very good at this..
I have received various memory leaks whilst running my game and I wanted to understand how to interpret the stack trace show in Instruments properly.
I attach a screenshot of the ObjectAllocation instrument output . Even when I zoom filter I don't manage to filter the data in the ObjectSummary .
The peaks in memory usage in 1 happen when the GameScene is initialized and all the data is loaded (ParallaxBackground, CCSpriteBatchNode) and Sprites and bullets frames are created (in an CCArray of spriteFrames).
The big blue peak is just at load time but the app freezes and then crashes only after a while and from the graph I see that the memory usage (blue bar) has gone down.. so I don't quiet get that. Also, whenver I try to use the leaks instrument the App crashes..
I know is a very silly question for someone experienced, but I just need some extra help getting started with this toolset.
I think the memory problem are due to the sprites I allocate in sprite cache classes, but I am not sure on this and hence wanted to investigate this using Instruments but can't find out how to see what is the object causing the memory warning and how to access the stack trace..
PS: I am running on an iPod 4th generatio and I am using Cocos2D as library
EDIT: I do not also understand why if the Live Bytes are only 1.01 MB the App crashes and why I still receive a memory warning (see black flags). Is it due to some pointer referencing to some null variable or due to an excessive memory allocation? 1.01 MB doesn't seem much to me..
EDIT 2: Following Marion's advice I used the Activity Monitor and realized that the effective real memory usage is 55.39 MB. I misinterpreted the "live bytes" word. I will try to dig into this further and will leave the question as unaccepted for now to allow other people contribute. If I won't have any other answer within one-two days I'll mark as accepted the current answer. Thanks!
Thanks a lot!
If you want to find leaks, use Leaks instrument instead of Allocations. To find out, how much memory use at the moment, use ActivityMonitor.
If you will have problems with memory in cocos2d, you can try to purge cache. In cocos2d you can purge CCTextureCache, CCSpriteFrameCache, CCAnimationCache. It will release unused textures and frames.
If you want to check if all of unnessesary textures were removed from memory, you can place breakpoint to CCTextureCache class and call, for example, sharedTextureCache and look throw the content of textures_ dictionary. Or add some method to this class to be able to dump current state of cache.
I am working on an OpenGL application for the iPhone...
My app has only 2 views:
An OpenGL view and, as a subview for the OpenGL view, a view with the sole purpose of catching touch events...
The problem is that after about 10-15 minutes of keeping the app running on the device, I get a big (0.5s-1s) delay between every touchesMoved:withEvent: call
The animation runs smooth, and CPU usage is also not the problem (10% at most)
I have no idea what might be causing this
That is weird, eh.
This happens ON THE DEVICE right? When you are not running tethered from XCode?
I would guess you are using up a lot of memory, either a leak or just in some way using up more and more memory as time goes on.
Are you familiar with the various memory tools to watch what is going on?
Also, what about this: launch a few other large apps that remain in the background. Run your app until the problem exhibits. Then, kill the other apps. Does the problem suddenly go away? If so that would suggest you're low on memory.
Would be interested to hear.
For the last few weeks I've been tearing my hair out trying to get a tiling mechanism working on an iPhone. I need to scale and crop images of about 150mb so that they can be saved as tiles that will be requested by a scroll view, allowing the user to see the image in high resolution.
The problem is that these images are really pushing the bounds of what an iPhone can handle. It seems quite easy to scale these huge images down to 1000 or so across and do that tiling, but for large zoom levels I need to scale it mid-way, say 4000 across and that's too big. So I hit upon the idea of making medium sized blocks from the full sized image and tiling each of those and the medium zoom.
By creating an autoreleasepool around the inner loops, and draining it after each cycle I can mostly keep the memory under control but sometimes, and to me it seems random, memory is getting leaked, or at least not drained. I'm doing all this on a secondary thread and when it gets back to the first function in that thread I release the thread's own autoreleasepool and only then do the last memory artifacts get cleared. It doesn't seem to bother the simulator but the iPhone is much less forgiving and it crashes before it can complete the whole tiling process. The cropping code I am using is from Hive05
http://www.hive05.com/2008/11/crop-an-image-using-the-iphone-sdk/
Has anyone else had to deal with such massive images before? Is pre-generating tiles the best way to go? Any suggestions on why some loops would increase the memory and some not, or how to force every auto-released thing to clear on the inner pool instead of waiting for the outer pool?
Thanks for reading this far.
for got to add, these images are TIFs, so perhaps a direct reading of the bitmap info would be better than scaling and cropping the entire thing
First of all, I have serious doubts that an 150 MB image would fit in the device's memory, even if we're talking about a 3GS. That one has about 128 MB available memory for 3rd party apps maximum. See the device console messages and look for memory warnings, I guess you'll see that before crashing, the app emits them when trying to load your image. Reading the bitmap info in chunks would seem more sensible, as you'll be managing smaller sections at a time. I don't think Cocoa has a random-access file API, so you'll have to resort to a C function.
I've managed to write the loops that cycle through tiles of 1024x1024 and my iPhone 3G is able to finish the processing. It takes over 30 minutes though so it isn't great but that's what you get for working with 150mb TIF on a cellphone.
To keep the memory usage low I had to drain the AutoReleasepools after each iteration. Apple Tech Support pointed out that since the iPhone is a reference-counted environment rather than a garbage collected environment it is better to create a new AutoReleasePool at the start of each inner loop and drain it at the end of each loop than to create it before any loops start, drain it many times and then release it after the loops are done. Until I made that change my app would crash an iPhone but run fine on the simulator.
I'm programming an puzzle game for iPhone using openGL.
There Is one very weird "bug" ( I'm not sure what It is)... whenever I touch the screen a great number of times in a short period of time my app closes, without giving a warning or error.
What could be the cause ?, I guess It has something to do with the memory, but I would like to know.
Edit:
I also think this happens because I'm calling multiple functions every time the user touches the screen or moves his fingers.
Sounds like you're running out of memory.
A few quick tips that might help out:
Check your memory profile over time using Instruments. If you see a steady incline over time, it's likely to be a memory leak, or an inefficient algorithm that is allocating more memory than you need.
Use a static analyzer to help check for leaks, such as Clang.
Images and image-related files are particularly memory-hungry, so focus on efficiency for them. When you work with textures in OpenGL, use the PVRTC format, which offers awesome compression.
didReceiveMemoryWarning: is your friend - aka a good chance to throw out anything you don't absolutely need in memory. Better to be memory-efficient the whole time, though.
Try setting up an NSUncaughtExceptionHandler. You may also want to setup a signal handler.