I try to combine two UIImage with the following code:
- (void)combineImage:(UIImage *)image WithFrame:(CGRect)frame Completion:(ImageProcessorCompletionBlock)block {
__weak typeof(self) wSelf = self;
dispatch_async(_queue, ^{
if (wSelf) {
typeof(wSelf) sSelf = wSelf;
UIGraphicsBeginImageContextWithOptions(sSelf.originalImage.size, NO, 0.0);
[sSelf.originalImage drawInRect:CGRectMake(0, 0, sSelf.originalImage.size.width, sSelf.originalImage.size.height)];
[image drawInRect:frame];
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
dispatch_async(dispatch_get_main_queue(), ^{
if (block) {
block(result);
}
});
}
});
}
That works but when I check out the usage of memory, it scared me. Every time I run the method the memory rise up and never release. Sometimes I receive the memory warning. Can anyone tell me why and give me a solution to solve the problem? Thanks a lot!
Finally I figure out the problem.
UIGraphicsBeginImageContextWithOptions(sSelf.originalImage.size, NO, 0.0);
The first parameter is the size of the image and the last one is the scale factor. At the beginning I have already set the image size same as the original one. But I also set the scale as 0.0, which means it is set to the scale factor of the device’s main screen. So the result image is enlarged.
If I run the code several times, the result's size gets bigger and bigger, finally it use up the memory and I receive the warning.
Related
so i am trying to make an app that will let the user change the color of the UIImage, for that i am using this function i found
- (UIImage *)imageWithTintColor:(UIColor *)color fraction:(CGFloat)fraction
{
if (color)
{
UIImage *image;
if ([UIScreen instancesRespondToSelector:#selector(scale)])
{
UIGraphicsBeginImageContextWithOptions([self size], NO, 0.f);
}
else
{
UIGraphicsBeginImageContext([self size]);
}
CGRect rect = CGRectZero;
rect.size = [self size];
[color set];
UIRectFill(rect);
[self drawInRect:rect blendMode:kCGBlendModeDestinationIn alpha:1.0];
if (fraction > 0.0)
{
[self drawInRect:rect blendMode:kCGBlendModeSourceAtop alpha:fraction];
}
image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
return self;
}
everything works but the CG raster Data is growing in memory
I found the problem, and it was my bad logic, i am using 2 views one to show and one to work with ex:resize, move, rotate. And each time i was addingSubview to both where one of them need to hold just 1 at a time, a simple:
for (UIView *view in 2cndView.subviews)
{
[view removeFromSuperview];
}
did the trick for me
I have been fighting with my app, that suddenly would not launch properly, for some time now. It turned out that when I had switched a number of images' Render as to Template in the Image asset file, it caused the app to totally bomb out. CG Raster Data was growing exponentially and finally caused the app to stop and Xcode just said
Lost connection with iPhone.. check connections etc
It would appear that during every launch the images get reprocessed for this 'Template' setting, which consumed a disgusting amount of RAM and actually left it unable to boot. To solve this, I lowered the resolution of the images - as simple as that.
I have a scrollView in which i load images into from the net .I sometimes get memory warnings, which i assume are because i am doing something wrong with the images loader.
I am trying to fix little things, and i just wanted to show the code here, and hear maybe there are more things i can fix to get rid of this warnings.
So every time the scroller (iPad) has only 4/5 images that are : current page-3->current page+3.
This is how i load the images(every image has also a blur effect with Apple's classes) :
(should i allocated imageView every time? can i improve something here? )
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^
{
NSData *imdata2 = [NSData dataWithContentsOfURL:url];
dispatch_async(dispatch_get_main_queue(), ^
{
UIImage *theImage=[UIImage imageWithData:imdata2 scale:1];
UIImage *LightImage = [theImage applyLightEffect];
UIImage *scaledImage =[resizer resizeImageToWidth:[Globals sharedGlobals].imagesWidth WithImage:theImage];
CGRect viewSizeBack=CGRectMake(scroller.bounds.size.width*toPage , 0, scroller.bounds.size.width, scroller.bounds.size.height);
int x=[Globals sharedGlobals].pageMargins;
int y=([UIScreen mainScreen].bounds.size.height-scaledImage.size.height)/2;
CGRect viewSizeFront=CGRectMake(x , y, scaledImage.size.width,scaledImage.size.height);
UIImageView *backImageView=[[UIImageView alloc] initWithFrame:viewSizeBack];
UIImageView *frontImageView=[[UIImageView alloc] initWithFrame:viewSizeFront];
backImageView.layer.cornerRadius = 0.0;
backImageView.layer.masksToBounds = YES;
backImageView.image=LightImage;
frontImageView.layer.cornerRadius = 0.0;
frontImageView.layer.masksToBounds = YES;
frontImageView.image=scaledImage;
frontImageView.layer.borderWidth=1.0;
frontImageView.layer.borderColor=[UIColor colorWithRed:255.0 green:255.0 blue:255.0 alpha:1.0].CGColor;
[backImageView addSubview:frontImageView];
backImageView.tag=toPage;
frontImageView.tag=toPage;
[scroller addSubview:backImageView];
});
});
You should only ever have 3 images loaded at a maximum - the previous page (if it exists), the current page and the next page.
Any other images you have loaded above this is wasteful because you can't see them and they're just taking up memory for no good reason. If the images aren't too big then you can maintain them in memory and purge them when you get a warning, but for large images this will still generally cause you issues.
If you don't use ARC then add this:
[backImageView autorelease];
[frontImageView autorelease];
In my iPhone app, I have a large image that I've cached to disk and I retrieve it just before I hand the image to a class that does a lot processing on that image. The receiving class only needs the image briefly for some initialization and I want to release the memory that the image is taking up as soon as possible because the image processing code is very memory intensive, but I don't know how.
It looks something like this:
// inside viewController
- (void) pressedRender
{
UIImage *imageToProcess = [[EGOCache globalCache] imageForKey:#"reallyBigImage"];
UIImage *finalImage = [frameBuffer renderImage:imageToProcess];
// save the image
}
// inside frameBuffer class
- (UIImage *)renderImage:(UIImage *)startingImage
{
CGContextRef context = CGBitmapCreateContext(....)
CGContextDrawImage(context, rect, startingImage.CGImage);
// at this point, I no longer need the image
// and would like to release the memory it's taking up
// lots of image processing/memory usage here...
// return the processed image
CGImageRef tmpImage = CGBitmapContextCreateImage(context);
CGContextRelease(context);
UIImage *renderedImage = [UIImage imageWithCGImage:tmpImage];
CGImageRelease(tmpImage);
return renderedImage;
}
This may be obvious, but I'm missing something. Thank you.
#Jonah.at.GoDaddy is on the right track, but I would make all of this more explicit rather than relying on ARC optimizations. ARC is much less aggressive in debug mode, and so your memory usage may become too high when you're debugging unless you take steps.
UIImage *imageToProcess = [[EGOCache globalCache] imageForKey:#"reallyBigImage"];
First, I'm going to assume that imageForKey: does not cache anything itself, and does not call imageNamed: (which caches things).
The key is that you need to nil your pointer when you want the memory to go away. That's going to be very hard if you pass the image from one place to another (which Jonah's solution also fixes). Personally, I'd probably do something like this to get from image->context as fast as I can:
CGContextRef CreateContextForImage(UIImage *image) {
CGContextRef context = CGBitmapCreateContext(....)
CGContextDrawImage(context, rect, image.CGImage);
return context;
}
- (void) pressedRender {
CGContextRef context = NULL;
// I'm adding an #autoreleasepool here just in case there are some extra
// autoreleases attached by imageForKey: (which it's free to do). It also nicely
// bounds the references to imageToProcess.
#autoreleasepool {
UIImage *imageToProcess = [[EGOCache globalCache] imageForKey:#"reallyBigImage"];
context = CreateContextForImage(imageToProcess);
}
// The image should be gone now; there is no reference to it in scope.
UIImage *finalImage = [frameBuffer renderImageForContext:context];
CGContextRelease(context);
// save the image
}
// inside frameBuffer class
- (UIImage *)renderImageForContext:(CGContextRef)context
{
// lots of memory usage here...
return renderedImage;
}
For debugging, you can make sure that the UIImage is really going away by adding an associated watcher to it. See the accepted answer to How to enforce using `-retainCount` method and `-dealloc` selector under ARC? (The answer has little to do with the question; it just happens to address the same thing you might find useful).
you can autorelease objects right away in the same method. I think you need to try to handle the "big-image" process within one methods to use #autorelease:
-(void)myMethod{
//do something
#autoreleasepool{
// do your heavy image processing and free the memory right away
}
//do something
}
I'm trying to make a photo slider similar to iOS's photos app. I've seen PhotoScroller, and I'm using initWithContentsOfFile.
CATiledLayer seems like a good idea, except I have no way of pre-generating tiles. The tiles also take up a lot of space. Images are part of a document bundle synced up with iCloud. Photos are typically JPEG. From hours of reading it seems like generating the tiles on the fly is slower than just loading the whole image.
It seems like a majority of the time is spent in decompressing the image anyway. And moving it to a background queue and displaying a smaller image should work well. So that's what I'm trying to do. And it works to a point, but if I slide without waiting for the image to load there's still somewhat of a stutter, which sometimes causes the scroll view to hang momentarily (when paging).
This is the function that sets the image:
- (void)setImage:(UIImage *)image placeholder:(UIImage *)placeholder
{
_image = image;
self.zoomScale = 1.0;
imageView.image = nil;
imageSize = image.size;
imageView.frame = CGRectMake(0, 0, image.size.width, image.size.height);
MachTimer *timer = [MachTimer new];
[timer start];
imageView.image = placeholder;
NSLog(#"placeholder: %f", [timer elapsedSeconds]);
//imageView.layer.contents = (id)placeholder.CGImage;
self.contentSize = image.size;
[self setMaxMinZoomScalesForCurrentBounds];
self.zoomScale = self.minimumZoomScale;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
MachTimer *timer = [MachTimer new];
[timer start];
UIGraphicsBeginImageContext(CGSizeMake(1, 1));
[image drawAtPoint:CGPointZero];
UIGraphicsEndImageContext();
NSLog(#"decode: %f", [timer elapsedSeconds]);
dispatch_sync(dispatch_get_main_queue(), ^{
if(_image == image) {
MachTimer *timer = [MachTimer new];
[timer start];
imageView.image = image;
NSLog(#"display: %f", [timer elapsedSeconds]);
//imageView.layer.contents = (id)image.CGImage;
}
});
});
}
My "placeholder" times are about 0.00005 - 0.00006 seconds (decompress and display), and they're 480px tall. My "decode" times (for full image) are about 0.8 to 1.2 seconds. "display" is about 0.0001 seconds (which is about 0.1 milliseconds).
So with those times the UI should be smooth as butter, but it isn't.
I've even tried to go as far as setting contents of a regular UIView to the CGImage. I've tried iOS 6.0's drawsAsynchronously, and that seems to make it a little worse.
What am I doing wrong?
EDIT:
I've pushed my sample project to GitHub:
https://github.com/lukescott/PhotoScroller
I would create a background thread for hard work (photo load or decode) and when its done then delegate UI work (draw or whatever) to main thread using one of tools (queues, msgs, etc).
I'm trying to create previews images of pages in a PDF
but I have some problems with the release of memory.
I wrote a simple test algorithm that cycles on the problem,
the app crashes near the 40th iteration:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *pdfPath = [documentsDirectory stringByAppendingPathComponent:#"myPdf.pdf"];
CFURLRef url = CFURLCreateWithFileSystemPath( NULL, (CFStringRef)pdfPath, kCFURLPOSIXPathStyle, NO );
CGPDFDocumentRef myPdf = CGPDFDocumentCreateWithURL( url );
CFRelease (url);
CGPDFPageRef page = CGPDFDocumentGetPage( myPdf, 1 );
int i=0;
while(i < 1000){
UIGraphicsBeginImageContext(CGSizeMake(768,1024));
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBFillColor(context, 1.0,1.0,1.0,1.0);
CGContextFillRect(context,CGRectMake(0, 0, 768, 1024));
CGContextSaveGState(context);
CGContextTranslateCTM(context, 0.0, 1024);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextDrawPDFPage(context, page);
CGContextRestoreGState(context);
// --------------------------
// The problem is here (without this line the application doesn't crash)
UIImageView *backgroundImageView1 = [[UIImageView alloc] initWithImage:UIGraphicsGetImageFromCurrentImageContext()];
// --------------------------
UIGraphicsEndImageContext();
[backgroundImageView1 release];
NSLog(#"Loop: %d", i++);
}
CGPDFDocumentRelease(myPdf);
The above-mentioned line seems to generate a memory leak,
however, instruments doesn't show memory problems;
Can I escape from this kind of mistake?someone can explain me in which way?
Are there other ways to show previews of a pdf?
UPDATE
I think the problem isn't the release of UIImage created by the method UIGraphicsGetImageFromCurrentImageContext() but the release of UIImageView created with this autorelease image.
I have divided the line of code in three steps:
UIImage *myImage = UIGraphicsGetImageFromCurrentImageContext();
UIImageView *myImageView = [[UIImageView alloc] init];
[myImageView setImage: myImage]; // Memory Leak
The first and second lines doesn't create memory leaks so I think that the method UIGraphicsGetImageFromCurrentImageContext is not the problem.
I also tried as follows but the problem persists:
UIImageView *myImageView = [[UIImageView alloc] initWithImage:myImage];
I think there is a memory leak in the release of a UIImageView that contains a UIImage with the autorelease property.
I tried to write my object UIImageView inheriting a UIView as explained in this thread.
This solution works but isn't very elegant, it's a workaround, I would prefer to use the object UIImageView solving the memory problem.
The problem is this:
UIGraphicsGetImageFromCurrentImageContext()
returns an autoreleased UIImage. The autorelease pool holds on to this image until your code returns control to the runloop, which you do not do for a long time. To solve this problem, you would have to create and drain a fresh autorelease pool on every iteration (or every few iterations) of your while loop.
I know it's an old question, but I've just been banging my head against the wall on this for a few hours. In my app repeatedly calling
UIImage *image = UIGraphicsGetImageFromCurrentImageContext()
in a loop does hold on to the memory despite me calling image = nil; Not sure how long the app would keep hold of the memory before freeing, but it's certainly long enough for my app to get a memory warning then crash.
I managed to solve it finally by wrapping the code that calls / uses the image from UIGraphicsGetImageFromCurrentImageContext() in #autoreleasepool. So I have:
#autoreleasepool {
UIImage *image = [self imageWithView:_outputImageView]; //create the image
[movie addImage:image frameNum:i fps:kFramesPerSec]; //use the image as a frame in movie
image = nil;
}
Hope that might help someone.
For future reference here's what I did to solve this (tested in Swift 4).
I was calling the function below for every new image downloaded from the internet (on a utility queue). Before implementing the autorelease pool it would crash after processing about 100.
For simplicity, in the resizeImage function I've removed needed code except for the autoreleasepool and the part that was leaking.
private func resizeImage(image: UIImage, toHeight: CGFloat) -> UIImage {
return autoreleasepool { () -> UIImage in
[...]
let newImage = UIGraphicsGetImageFromCurrentImageContext() //Leaked
UIGraphicsEndImageContext()
return newImage!
}
}
I hope this helps!
For those who tried all solution above and still has a memory leak, check if you are using a dispatch queue. If so, be sure to set its autoreleaseFrequency to .workItem. Or the autorelease pool you set up inside the will not execute.
DispatchQueue(label: "imageQueue", qos: .userInitiated, autoreleaseFrequency: .workItem)
Hope it helps, it has bugged me for hours until I finally realize that's DispatchQueue that is holding the block.
Is this code running on the main thread? The documentation of the UIGraphicsGetImageFromCurrentImageContext (link) says it must run that way.
your line of crash you can update it like following
get one UIimage out of loop
rendered_image = UIGraphicsGetImageFromCurrentImageContext();