I'm working on a iPad Magazine and I'm using a lot of images (background, slideshow and animation) and the memory utilized is very high.
I've read the following method uses a lot of memory
UIImage *picture = [UIImage imageNamed:#"myFile.png"];
And they recommended using this one
NSString *fullpath = [[[NSBundle mainBundle] bundlePath] stringByAppendingString:#"/myFile.png"];
imageView.image = [UIImage imageWithContentsOfFile:fullpath];
But I've found another method as well
imageView.image = [[UIImage alloc] initWithContentsOfFile: [[NSBundle mainBundle] pathForResource:#"myFile" ofType:#"png"]];
In order to optimize my app, which method should I use? All my images are .jpg and were saved for web in Photoshop.
All 3 methods will use the same amount of memory. The differences are the following:
Using [UIImage imageNamed:#"myFile.png"] image is cached in memory for faster reuse. This is good for small images used several times in your application (image background, etc). Cache is removed for non used images when memory warning is received.
Using [[UIImage alloc] initWithContentsOfFile:path] image is not cached and you can "force" release of memory by calling [image release] or setting property to nil using ARC. You have a better management of when memory is released
Using [UIImage imageWithContentsOfFile:fullpath] is just equivalent to [[[UIImage alloc] initWithContentsOfFile:path]autorelease]
Related
UIImageView has animationImages for animating sequence of images. That works fine. But It holds the images object. So There is a spike in use of memory when this animation is happening. I tried NSTimer for setting image property of that image view, But it doesn't work.
Can we achieve this in any other approach?
Instead of looking for alternatives, just try to correct the existing code.
The best practice of allocating an image for animationImages should be using initWithContentsOfFile instead of imageNamed:
imageNamed: it cache’s your images and you lose control over the memory - there's no guarantee that releasing the object will actually release the image but does provide faster loading of images second time around as they are cached.
imageWithContentsOfFile: it does not cache images and is more memory friendly however as it does not cache images and the heavier images are loaded much slower.
When the animation does stop, just release the image collection array. If you are using ARC then make it the image collection array to nil.
Best Practice:
for(int itemIndex = 0; itemIndex < 20; itemIndex++) {
NSString *filePath = [[NSBundle mainBundle] pathForResource:#"myImage1" ofType:#"png"];
UIImage *image = [[UIImage alloc] initWithContentsOfFile:filePath];
[imageArray addObject:image];
}
After the Animation:
imageArray = nil;
My iOS app utilizes a loop to cycle through images in a folder.
My application is supposed to loop through a total of 2031 images (sized 1200x900) inside a folder. The images were taken at 8fps and each image will be displayed as the loop continues to simulate a video clip. After the 696th picture, the images will cease to be displayed in the UIImageView although the app will continue looping.
I tested to see if the disconnect was because of the picture not existing
I started the loop at picture 200, but after picture 896 the UIImageView stop displaying the pictures.
The Code:
imgName = [NSString stringWithFormat:#"subject_basline_mat k (%d).png",jojo];
jojo++;
imageToCrop.image = [UIImage imageNamed:imgName]; //imageToCrop is the name of the UIImageView image and it is set to the image file here
imageToCrop.image = [self imageWithImage:imageToCrop.image convertToSize:self.imageToCrop.frame.size]; //Here the image is converted to fit the bounds of the simulator which is 320x240
The code loops due to a timer that loops it about once every 0.8 seconds.
I ran my code with instruments to see if there was a memory problem occurring,and instruments is very heavy on my computer. As such, my application ran quite slowly. However, when I arrived at the 696th picture, the pictures kept displaying themselves. It was almost as if my application running too quickly caused the picture to not be displayed... which I don't really understand.
The only memory heavy part of the image switching seems to be the size conversion step which is called by the line imageToCrop.image = [self imageWithImage:imageToCrop.image convertToSize:self.imageToCrop.frame.size];
imageToCrop.image = [self imageWithImage:imageToCrop.image convertToSize:self.imageToCrop.frame.size];
The method "imageWithImage" is here:
- (UIImage *)imageWithImage:(UIImage *)image convertToSize:(CGSize)size {
#autoreleasepool {
UIGraphicsBeginImageContext(size);
[image drawInRect:CGRectMake(0, 0, size.width, size.height)];
UIImage *destImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return destImage;
}
And the line [image drawInRect:CGRectMake(0, 0, size.width, size.height)]; uses around up the most memory out of all the image management in the app.
Any Ideas as to why my app will only display a certain amount of images?
Try loading the full-size images from the app bundle by URL. For example:
#autoreleasepool {
NSString *imgName = [NSString stringWithFormat:#"subject_basline_mat k (%d)",jojo];
NSURL *imageURL = [[NSBundle mainBundle] URLForResource:imgName withExtension:#"png"];
UIImage *image = [UIImage imageWithContentsOfFile:[imageURL path]];
imageToCrop.image = [self imageWithImage:image convertToSize:self.imageToCrop.frame.size];
}
Almost for sure your problem is [UIImage imageNamed:imgName]. There are hundreds of posts here on the pitfalls of using it. The issue is that it caches the images - its real purpose is for some small number of images in your bundle.
If you have oodles of images, get the path to the image, then get the image through a URL or file pointer. That way its not cached. Note that when you do this, you lose the automatic "get-retina-image-automatically", and so you will need to grab the appropriately sized image depending on whether the device is retina or not.
I've some trouble with memory on my app. I've checked Instruments to get more clue about this issue and i've found that 79% of my memory is used by this :
So i've searched on Google and some people said that is image caching which saved in memory all my images. Maybe it comes from my allocation ?
Here is how i call my images :
info = [InfoModel getInfo:[NSString stringWithFormat:#"%d", self.idEnigme]];
myImage = [UIImage imageNamed:[NSString stringWithFormat:#"res/img/%#", [info objectForKey:#"path1"]]];
myImageView = [[UIImageView alloc] initWithImage:myImage];
myImageView.frame = CGRectMake(0, 200, [[UIScreen mainScreen] bounds].size.width, 400);
[self.scrollView addSubview:myImageView];
Info is a class where i parse a Json file where are my path to images.
Thanks for helping, this drives me crazy.
iOS automatically caches your image for future use when you call imageNamed:
As discussed in a few places, including here:Does UIImageView cache images?
You can get around this caching if you know you are only going to create it once by using
[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:fileName ofType:nil]]
instead
I wouldn't worry about that too much, the UIImage cache is cleared when the app receives a low memory warning. It's all handled automatically, so any images that are no longer in use will be flushed from memory at this point.
So if your app is crashing from running out of memory it is not likely because the OS is caching images that are no longer in use.
You can handle your own caching of images by using initWithData instead of imageNamed but I doubt this solution will help you.
I'm very worried about the following screen. When i launch "Instruments" in Allocations mode, i see every image of my app adding to "Living". I really don't understand how it could be possible...
I've found the problem and i solved it. I'll explain you what was the problem, maybe it could help someone.
The real problem was my UIImage init. Initially i allocated my UIImage in method like the following code :
NSString* fileName = [NSString stringWithFormat:#"%#%#%#", name, number, ext];
UIImage *myImageHeader = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:fileName ofType:nil]];
UIImageView *myImageViewHeader = [[UIImageView alloc] initWithImage:myImageHeader];
myImageViewHeader.frame = CGRectMake(0, 0, [[UIScreen mainScreen] bounds].size.width, 277);
[self.scrollView addSubview:myImageViewHeader];
Finally i've decided to create a UIImageview in my .h via a property and to set it in my method, like this :
#.h
#property (weak, nonatomic) IBOutlet UIImageView *headerImage;
#.m
[self.headerImage setImage:[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:fileName ofType:nil inDirectory:nil]]];
By this way i saved a lot of memory but i still have leaks. So i decided to delete the image in my UIImageView after use :
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^(void){
self.headerImage.image = nil;
});
Now, my app only use 8mb of memory and manage memory correctly.
Thx for helping !
I am attempting to run two UImageViews that have multiple arrays of animations they load and animate based on a selection the user makes. For example, here is one method:
-(void)initiateAnimations {
nullAnimation = [NSArray arrayWithObjects:
[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"null0002" ofType:#"png"]],
[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"null0003" ofType:#"png"]],
[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"null0004" ofType:#"png"]],
[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"null0005" ofType:#"png"]],
[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"null0006" ofType:#"png"]],
[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"null0007" ofType:#"png"]],
[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"null0008" ofType:#"png"]],
[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"null0009" ofType:#"png"]],
[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"null0010" ofType:#"png"]], nil];
}
And here is an IBAction calling the animation method:
-(IBAction)nullani {
player.animationImages = nullAnimation;
player.animationDuration = 0.50;
player.animationRepeatCount = 1;
[player startAnimating];
}
It all works well at first, but keep in mind i have about 5-6 other arrays of animations roughly with the same size images. They arent huge, ranging from 12-80k .png files. When i attempt to animate after a few times, I am recieving this error in the output:
2013-03-16 01:34:44.438 [3316:907] Received memory warning.
After i receive this message, any new animation loaded will crash the app.
I ran it through Instruments and was unable to find any leaks, and the output gives me nothing upon crash.
Is there any memory issues here? how can i get rid of this issue? thanks.
Some ideas:
1) Never have more than 1 animation loaded into an array. Once you stop one animation, and are ready to start another, delete the first animation and replace the image the viewer sees with the single image that should be showing. If you can determine the exact image that was showing (and am doubtful of this) then you can replace the array with a single image and the image will not flicker.
2) If you cannot do 1), then try using Core Animation directly (more work for you), and do the animation yourself. This gives you more control over memory usage (you could cache image bitmaps on the file system).
3) Using a Mac and AVFoundation or QTKit, make an animation from images, then create a "movie" that you start and stop instead of the image sequence. In this case you'd replace the static images in the bundle with movie objects.
i have a UIScrollView which holds different UIView container. Each container has to load six UIImages. When scrolling i need to adjust the contents within the "layoutSubviews" method.
Unfortunately loading these images affects in hiccups when the new container and the images will be created.
I´m loading the images async via "dispatch_async". I also used small 32x32px thumbnails which will be replaced with the full image 256x256px image. Unfortunately its stuttering..
Here´s the code of the "initWithFrame" method of such a UIView.
These UIViews will later be added as a subview to the UIView container.
// load ThumbnailImage and replace it later with the fullImage
NSString* thumbImageName = [self.data.imageName stringByAppendingString:#"_small"];
NSString* fileLocation = [[NSBundle mainBundle] pathForResource: thumbImageName ofType:#"png"];
UIImage* image = [UIImage imageWithData:[NSData dataWithContentsOfFile:fileLocation]];
[self setBackgroundImage:img forState:UIControlStateNormal];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
dispatch_async(dispatch_get_main_queue(), ^{
NSString* fileLocation = [[NSBundle mainBundle] pathForResource: self.data.imageName ofType:#"png"];
UIImage* image = [UIImage imageWithData:[NSData dataWithContentsOfFile:fileLocation]];
[self setBackgroundImage:img forState:UIControlStateNormal];
});
});
Is this the faster way to load images into a UIView?
How does Apple implemented the really fluid image view inside the "Photo.app" when scrolling between different fullscreen images?
I don´t know if it would make sense to use CoreImage?
Any advice would be great!
Thanks for any help and your time.
Have a nice day.