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();
Related
I make use of the UIImage+Resize library to resize my images directly after taking them.
I do get a memory leak with the following code:
CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, srcSize.width, srcSize.height), imgRef);
UIImage* resizedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGDataProviderCreateWithCopyOfData memory leak in Instruments.
I tried adding it into a #autoreleasepool as per other StackOverflow posts.
Note: You've probably have already fixed your problem, this answer for future readers having the same problem.
I've figured out what's going on my own implementation (video analysis with GPUImage).
I needed to add an autoreleasepool closure around the call to CGBitmapContextCreateImage caller (it also calls CGDataProviderCreateWithCopyOfData).
func run() {
while (parent != nil) {
if semaphore.acquireSemaphore(5000) {
autoreleasepool { // Without this I was leaking images until crash.
parent?.analyseImage(self.sampleBuffer!, lineFinder:finder) //This calls CGBitmapContextCreateImage
}
}
}
thread = nil
}
I try to take screenshot of uiwebview and send it with observer to another UIImageView in another class.
I using this method to take screenshot:
-(UIImage*)takeScreenshoot{
#autoreleasepool {
UIGraphicsBeginImageContext(CGSizeMake(self.view.frame.size.width,self.view.frame.size.height));
CGContextRef context = UIGraphicsGetCurrentContext();
[self.webPage.layer renderInContext:context];
UIImage *__weak screenShot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return screenShot;
}
}
But then I have problem. Everytime I take screenshot with this method, memory rate grows about 10-15mb and it's not realising it. And if I take screenshot in every webviewdidfinishload, you can imagine how much it can take memory!
How can I fix that issue?
If possible try to use [UIScreen snapshotViewAfterScreenUpdates] which returns UIView .
This is the snapshot of currently displayed content (snapshot of app).
Even apple also says " this method is faster than trying to render the contents of the screen into a bitmap image yourself."
According to your code, you are passing this bitmap image to just display in some other UIImageView. so i think using UIScreen method is appropriate here.
To display UIWebView part only->
Create another UIView instance. Set its frame to the frame of your webView.
Now add this screenShot view as subView to createdView and set its frame such that webView portion will be displayed.
Try calling CGContextRelease(context); after you have got your screen shot.
Or as #Greg said, remove the line and use UIGraphicsGetCurrentContext() directly
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 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
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();