I have written the following code snippet to take screen snapshot:
UIGraphicsBeginImageContext(animationView.frame.size);
[[window layer] renderInContext:UIGraphicsGetCurrentContext()];
UIImage* screenshot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
But, UIGraphicsGetImageFromCurrentImageContext seems to be leaking. Is this correct?
In Instruments I could not get the exact leak point. In activity monitor I observed that when I switch to the UI that executes the above code snippet memory increments by some MB. After this point it never decreases.
Does UIGraphicsGetImageFromCurrentImageContext has memory leak? How do I solve this?
Edit
Instruments analysis
Activity Monitor: shows the memory hike when this line of code is executed; never decreases even after releasing screenshot (UIImage)
Leaks and allocation, Heap Snapshot: Does not show any leak OR this allocation.
You have just created a UIImage with data for your animationView (which could be some MB). Perhaps you should wrap this functionality in an autorelease pool.
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
UIImage* screenshot = UIGraphicsGetImageFromCurrentImageContext();
//[screenshot retain]; //If you want precise control over when it is released and you will use it later.
[pool release];
CGContextRef context = UIGraphicsGetCurrentContext();
/* you code */
CGContextRelease(context);
clear the context when done
Related
I have a UIImage that I'm loading into one of my app's views. It is a 10.7 MB image, but when it loads in the app, the app's resource usage suddenly jumps by 50 MB. Why does it do this? Shouldn't memory used increase by only about 10.7MB? I am certain that loading the image is what causes the jump in memory usage because I tried commenting these lines out and the memory usage went back to around 8 MB. Here's how I load the image:
UIImage *image = [UIImage imageNamed:#"background.jpg"];
self.backgroundImageView = [[UIImageView alloc] initWithImage:image];
[self.view addSubview:self.backgroundImageView];
If there is no way to decrease the memory used by this image, is there a way to force it to deallocate when I want it to? I'm using ARC.
No, it should not be 10.7MB. The 10.7MB is the compressed size of the image.
The image loaded in to the UIImage object is a decoded image.
For each pixel in the image 4 bytes (R,G,B and Alpha) are used, therefore you can calculate the memory size, height x width x 4 = total bytes in memory.
So the moment you loaded the image into memory it will take up lots of memory, and since a UIImageView is used to present the image and as a subview the images is kept in memory.
You should try and change the size of the image to match the size of the iOS screen size.
As #rckoenes said
Don't show the images with high file size.
You need to resize the image before you display it.
UIImage *image = [UIImage imageNamed:#"background.jpg"];
self.backgroundImageView =[self imageWithImage:display scaledToSize:CGSizeMake(20, 20)];//Give your CGSize of the UIImageView.
[self.view addSubview:self.backgroundImageView];
-(UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
//UIGraphicsBeginImageContext(newSize);
// In next line, pass 0.0 to use the current device's pixel scaling factor (and thus account for Retina resolution).
// Pass 1.0 to force exact pixel size.
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
You can do one thing. if you can afford 50 MB for this image. If this image with 10 mb size is that much critical to your application then. you can release it just after its use to keep memory usage in control.
As you are using ARC there is no option for release but you can do this
#autoreleasepool {
UIImage *image = [UIImage imageNamed:#"background.jpg"];
self.backgroundImageView = [[UIImageView alloc] initWithImage:image];
[self.view addSubview:self.backgroundImageView];
}
using autoreleasepool it will be sure that after this autoreleasepool{} block memory for fat image will be deallocated. making your device RAM happy again.
Hope it helps !
What are the rules for managing memory for CGImageRefs with ARC? That is, can someone help me to the right documentation?
I am getting images from the photo library and creating a UIImage to display:
CGImageRef newImage = [assetRep fullResolutionImage];
...
UIImage *cloudImage = [UIImage imageWithCGImage:newImage scale:scale orientation:orientation];
Do I need to do CGImageRelease(newImage)?
I'm getting memory warnings but it doesn't seem to be a gradual buildup of objects I haven't released and I'm not seeing any leaks with Instruments. Puzzled I am.
No, you do not need to call CGImageRelease() on the CGImageRef returned by ALAssetRepresentation's convenience methods like fullResolutionImage or fullScreenImage. Unfortunately, at the current time, the documentation and header files for these methods does not make that clear.
If you create a CGImageRef yourself by using one of the CGImageCreate*() functions, then you own it and are responsible for releasing that image ref using CGImageRelease(). In contrast, the CGImageRefs returned by fullResolutionImage and fullScreenImage appear to be "autoreleased" in the sense that you do not own the image ref returned by those methods. For example, say you try something like this in your code:
CGImageRef newImage = [assetRep fullResolutionImage];
...
UIImage *cloudImage = [UIImage imageWithCGImage:newImage
scale:scale orientation:orientation];
CGImageRelease(newImage);
If you run the static analyzer, it will issue the following warning for the CGImageRelease(newImage); line:
Incorrect decrement of the reference count of an object that is not
owned at this point by the caller
Note that you will get this warning regardless of whether your project is set to use Manual Reference Counting or ARC.
In contrast, the documentation for the CGImage method of NSBitmapImageRep, for example, makes the fact that the CGImageRef returned is autoreleased more clear:
CGImage
Returns a Core Graphics image object from the receiver’s
current bitmap data.
- (CGImageRef)CGImage
Return Value
Returns an autoreleased CGImageRef opaque type based on the receiver’s
current bitmap data.
I have bisected my code and determined that this causes a memory leak. Can somebody explain why?
self.overlay is an UIImageView, set in IB. The property is declared as (nonatomic, weak).
If I comment out this while block I don't get the malloc error. If I only comment out the // Graphics operations here (as shown below) I still get the malloc error.
UIGraphicsBeginImageContextWithOptions(self.overlay.frame.size, NO, 0);
// Graphics operations here
self.overlay.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
I'm using the following code to rotate an image
http://www.platinumball.net/blog/2010/01/31/iphone-uiimage-rotation-and-scaling/
that's one of the few image transformations that I do before uploading an image to the server, I also have some other transformations: normalize, crop, resize.
Each one of the transformations returns an (UIImage*) and I add those functions using a category. I use it like this:
UIImage *img = //image from camera;
img = [[[img normalize] rotate] scale] resize];
[upload img];
After selecting 3~4 photos from the camera and executing the same code each time I get a Memory Warning message in XCode.
I'm guessing I have a memory leak somewhere (even though im using ARC). I'm not very experienced using the xCode debugging tools, so I started printing the retain count after each method.
UIImage *img = //image from camera;
img = [img normalize];
img = [img rotate]; // retain count increases :(
img = [img scale];
img = [img resize];
The only operation that increases the retain count is the rotation. Is this normal?
The only operation that increases the retain count is the rotation. Is this normal?
It's quite possible that the UIGraphicsGetImageFromCurrentImageContext() call in your rotate function ends up retaining the image. If so, it almost certainly also autoreleases the image in keeping with the normal Cocoa memory management rules. Either way, you shouldn't worry about it. As long as your rotate function doesn't itself contain any unbalanced retain (or alloc, new, or copy) calls, you should expect to be free of leaks. If you do suspect a leak, it's better to track it down with Instruments than by watching retainCount yourself.
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();