Loaded 50+ images from document directory in UIScrollview app get the crash.Getting " Connection to assets was interrupted or assets died (with memory warnings)". Can anyone suggest best way to load these images? Thanks in advance. My code is in Objective-C.
The best option for displaying Images in your case would be using a UITableView or UICollectionView because they internally dequeue cells when they are no longer displayed on the screen.
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In your case the UIScrollView does not dequeue its subviews, thus the screen contains the images all the time which consumes more amount of memory and the operating system closes (crashes) your app due to heavy memory usage.
You should use UITableView instead of UIScrollView.
But if they are very large images, it would crash when just load one image, unless it be preprocessed (resized).
Related
My application suppose to show images in full screen and i have lots of images in my list(more than 500 images).
I'm adding image view in scroll view with horizontal scrolling and paging. But I'm facing memory issues as loaded images will eat my device memory?
What is the best way to load images.
Don't attempt to use a vanilla UIScrollView to show a ton of content, especially if you're just going to dump it all in at load-time. As you've seen, that will inevitably crash due to memory pressure.
At a minimum use UICollectionView, which will at least reuse cells and allow a minimum of assets to be in memory at one time. However, the problem of a smooth, low-memory photo collection view is one that many apps encounter, and can have a lot of implementation gotchas. I recommend looking for a well-built component rather than trying to reinvent that particular wheel.
I have a bunches of cell that contain UIImageView in UICollectionView and i've using setImageWithURL to load image in each cell, but if it load too much (i.e 100 cell) my app become crashing. Its definitely because of memory issues, i know this is not rare case in Mobile platform, but i still need help from experient guys.
I think it come from setImageWithURL (AFNetworking) problem, it still keep the catch from previous image link and bytheway i've using infinity scrolled, so the system will hold all the images, and memory can not stand. I need a solution for clear the cath images file or some thing to manage the memory. Any help ?
In my app, I have a UITableView which displays fairly large images and loads a moderately designed Xib file to display it in. Each image is around 700KB to 1MB in size. The flow is virtually never ending, it loads more and more as we scroll down. So you can imagine that I am running into memory issues.
I have tried using SDImageCache and NSCache. The former used disk memory for caching images. In both cases, the caches somehow didn't clear images automatically. I had to manually clear them when I got a Received memory warning prompt. And each time I clear these caches, the memory freed seems to be lesser each subsequent time.
Now I confused as to which cache strategy I must use for such a long list of images. Might I be having some leaks somewhere? They certainly didn't show up when I profiled the app.
P.S.: I am loading the images from the web. Just to be clear.
From the docs:
UIImage
+(UIImage *)imageNamed:(NSString *)name
Discussion This method looks in the system caches for an image object
with the specified name and returns that object if it exists. If a
matching image object is not already in the cache, this method loads
the image data from the specified file, caches it, and then returns
the resulting object.
So I guess leaving this to the UIImage class is a good approach.
Hope this helps!
As we implemented it in both Android and iOS: once you can show on the screen only 2-3 images.
Load in memory 2 more for the downwards scroll and 2 more for the upwards one. So you have in memory 7 images. Display them. The other images must be stored in files (when you download them). If the user scrolls too fast, do not show all the sequence of the images, instead show some "loading" icons in place of the images. When the scrolling stops, show the appropriate image + the previous one + the next one + prepare 2 more (for upwards scroll) and 2 more for downwards scroll.
I have an iPad app which is crashing on iPad (First model) as it is running out of memory.
In the app I have a main view which adds as subviews about 20 UIScrollViews (custom class) each containing a UIImageView and UIImage. When the user moves to the next page, I remove all these subviews from the superview and then add 20 new UIScrollViews to the same view.
If I profile the app for allocations and memory leaks everything is ok - the memory allocated stays at about 2MB while the user scrolls left and right.
However if I look at the real memory usage in the Activity Monitor I can see that every time the user moves to a new page, the real memory increases by about 20MB. Eventually after a few new pages the app size hits 150+ MB and crashes.
Can anyone suggest what might cause this type of behaviour and how I can further troubleshoot this ?
Just a bit more info on the app structure :
In view did load the images are loaded into an NSMutableArray using initWithContentsOfFile.
You should not be maintaining these images in an array. Images consume a disproportionate amount of your limited RAM. There are a couple of approaches:
If you want to keep it simple, just don't store the images anywhere. Load the image property of the UIImageView by loading the image via initWithContentsOfFile and call it a day.
If you want some RAM caching for performance reasons, you could use imageNamed instead of initWithContentsOfFile. When the app receives a memory warning, the cache will automatically be purged.
I'd be inclined to use initWithContentsOfFile, but then manually cache in my own NSCache (which is like a NSDictionary, except you can set a countLimit of how many images it should hang on to).
By the way, you don't describe what technically happens when "the user moves to the next page." If you're simply refreshing the existing controls on the existing view controller, then everything is probably fine (once you fix the NSMutableArray problem I discuss above). If you're pushing/presenting to another view controller or scrolling controls off screen but neglecting to remove the old ones from their superview, then that will also cause problems. You might want to clarify what you're doing there.
Bottom line, you just need to make sure that when you go from one page to another, that you're not maintaining strong references to any old images or controls.
I'm building an application that requires a bunch of local images to be displayed in the imageview of a uitableviewcell. However, i'm having difficulty optimizing the performance of the uitableview. I've noticed two issues specifically: first, the view takes a while to load. Second, the scrolling gets laggy when new cells are displayed.
The viewDidLoad is loading in the images like this:
for (Object *object in self.objects)
{
object.thumbnail = [UIImage imageNamed:object.imageName];
}
this is obviously causing the long-load issue, but I'm not sure how else to get those images loaded. Is it a size issue? is this just a bad way of doing it?
The process of displaying the images also seems to be problematic, in other words, even after the images have been assigned to the thumbnail property, they still take too long to be drawn.
Although this is a specific case, I'm curious more generally on how apple loads images in photos so efficiently. Any insights? thanks
Whenever I find that my UI is lagging, the first thing I suspect is that I am performing some operation synchronously (on the main thread) that should be performed asynchronously (on a background thread).
I am also very curious as to how exactly Apple is achieving that performance in the photo app. I am writing an app that has similar requirements as yours right now. My current approach is to load a bunch of photos from disk into memory asynchronously as soon as the user opens my view controller, and continue to load (and remove photos) from memory - ahead of time - as the user scrolls.
Currently, I load each photo from disk asynchronously in cell for row at index path, which is pretty fast, but causes this cascading effect to happen if you scroll quickly through the table view. That is, the cell will appear empty for a moment before the photo appears.
I hope this sheds some light for you.
You may also be interested in trying SDWebImage - which includes an image cache object that has been making my life easier when dealing with local photos.
They are doing everything in the background on various detached threads most likely. This will allow for a great deal of fluidity in applications that are hosting/presenting a great deal of information. I have created a photo gallery myself in various applications, loading many photos simultaneously from different web APIs and whatnot, and by simply creating new threads and managing the allocation efficiently and accurately, you can get a very smooth interface/interaction
Well, the long-load issue is caused by this part of your code - UIImage imageNamed:, because this method caches all the images on the same thread, and also could crash the app if the memory is overloaded.
Try looking at this library - it should do what you are trying to achieve :)
http://www.cocoacontrols.com/platforms/ios/controls/ktphotobrowser