UIGraphicsGetImageFromCurrentImageContext（） - 内存泄漏 [英] UIGraphicsGetImageFromCurrentImageContext() - Memory Leak

问题描述

我正在用 UIImagePickerControllerSourceTypeCamera 和一个自定义 cameraOverlayView 打开相机，这样我可以拍摄多张没有使用的照片照片步骤。

I am opening the camera with UIImagePickerControllerSourceTypeCamera and a custom cameraOverlayView so I can take multiple photos without the "Use Photo" step.

这很好用，但保存照片功能有内存泄漏。通过大量的调试和研究，我将其缩小到 UIGraphicsGetImageFromCurrentImageContext 函数。

This is working great, but there is a memory leak in the save photo function. Through a lot of debugging and research I have narrowed it down to the UIGraphicsGetImageFromCurrentImageContext function.

这是一个片段代码发生的地方：

Here is a snippet of code where it happens:

UIGraphicsBeginImageContextWithOptions(timestampedImage.frame.size, timestampedImage.opaque, [[UIScreen mainScreen] scale]);
[[timestampedImage layer] renderInContext:UIGraphicsGetCurrentContext()];
UIImage *finalTimestampImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

我已经搜索过互联网，似乎 UIGraphicsGetImageFromCurrentImageContext（） function（引自这个问题） 返回一个新的自动释放 UIImage 并将 finalTimestampImage ivar指向它。之前分配的 UIImage 从未实际发布过，其中的变量只是被重新命名为其他地方。

I have scoured the internet and it seems that the UIGraphicsGetImageFromCurrentImageContext() function (quoted from this SO question) "returns a new autoreleased UIImage and points the finalTimestampImage ivar to it. The previously allocated UIImage is never actually released, the variable to it is just repointed to somewhere else."

我尝试了很多解决方案显然对其他人有效：

I've tried so many solutions that have apparently worked for others:

• 添加 timestampedImage.layer.contents = nil; 在 UIGraphicsEndImageContext

添加 CGContextRef context = UIGraphicsGetCurrentContext（） ; 和 CGContextRelease（context）; 在 UIGraphicsEndImageContext

在 NSAutorele中包装上述代码段asePool

在<$ c $中包装整个 saveThisPhoto 函数c> NSAutoreleasePool

Wrapping the entire saveThisPhoto function in an NSAutoreleasePool

当相机弹出时创建 NSAutoreleasePool 当 didReceiveMemoryWarning 被调用时调用 [pool release]

Creating an NSAutoreleasePool when the camera pops up and calling the [pool release] when didReceiveMemoryWarning is called

调用 didReceiveMemoryWarning 时关闭相机弹出窗口，希望它将清除池

Closing the camera popup when didReceiveMemoryWarning is called, hoping it will clear the pool

以上所有可能的组合

然而我尝试的一切，当我拍照时我都能看到内存使用当我在设备上反复拍照时，上升而不是下降。

Yet everything I try, when I take photos I can see the Memory Utilized rising and not falling when I'm repeatedly taking photos on the device.

有谁知道如何释放自动释放由 UIGraphicsGetImageFromCurrentImageContext创建的对象？

Does anyone know how I can release the autorelease object created by UIGraphicsGetImageFromCurrentImageContext?

或者，是否有另一种方法可以制作 UIImage out of a $ code> UIImageView ？

Alternatively, is there an alternative way to make a UIImage out of an UIImageView?

编辑：

以下是所要求的完整功能。为了确保所有被清理，我们在那里添加了大量的额外发布。我已经完成并且系统地测试了 saveThisPhoto 中每个代码块的内存泄漏，它只发生在 UIGraphicsGetImageFromCurrentImageContext 块（上面的代码段）运行。

Here are the full functions as requested. There's a lot of extra releasing added in there just to try make sure everything is cleaned up. I have gone through and tested for the memory leak with each code block in saveThisPhoto systematically, and it only occurs when the UIGraphicsGetImageFromCurrentImageContext block (snippet above) is run.

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {

    NSLog(@"SAVING PHOTO");

    [self saveThisPhoto:info];

    picker = nil;
    [picker release];

    info = nil;
    [info release];

}

- (void)saveThisPhoto:(NSDictionary *)info {

    // Get photo count for filename so we're not overriding photos

    int photoCount = 0;

    if ([[NSUserDefaults standardUserDefaults] objectForKey:@"photocount"]) {
        photoCount= [[[NSUserDefaults standardUserDefaults] objectForKey:@"photocount"] intValue];
        photoCount++;
    }

    [[NSUserDefaults standardUserDefaults] setObject:[NSString stringWithFormat:@"%d", photoCount] forKey:@"photocount"];
    [[NSUserDefaults standardUserDefaults] synchronize];

    // Obtaining saving path

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *fileName = [NSString stringWithFormat:@"ri_%d.jpg", photoCount];
    NSString *fileNameThumb = [NSString stringWithFormat:@"ri_%d_thumb.jpg", photoCount];
    NSString *imagePath = [documentsDirectory stringByAppendingPathComponent:fileName];
    NSString *imagePathThumb = [documentsDirectory stringByAppendingPathComponent:fileNameThumb];

    // Extracting image from the picker and saving it

    NSString *mediaType = [info objectForKey:UIImagePickerControllerMediaType];

    // SAVE TO IPAD AND DB

    if ([mediaType isEqualToString:@"public.image"]){

        // Get Image

        UIImage *editedImage = [info objectForKey:UIImagePickerControllerOriginalImage];

        // Figure out image orientation

        CGSize resizedSize;
        CGSize thumbSize;

        if (editedImage.size.height > editedImage.size.width) {
            resizedSize = CGSizeMake(480, 640);
            thumbSize = CGSizeMake(150, 200);
        } else {
            resizedSize = CGSizeMake(640, 480);
            thumbSize = CGSizeMake(150, 113);
        }

        // MAKE NORMAL SIZE IMAGE

        UIImage *editedImageResized = [editedImage resizedImage:resizedSize interpolationQuality:0.8];

        // clean up the one we won't use any more

        editedImage = nil;
        [editedImage release];

        // ADD TIMESTAMP TO IMAGE

        // make the view

        UIImageView *timestampedImage = [[UIImageView alloc] initWithImage:editedImageResized];
        CGRect thisRect = CGRectMake(editedImageResized.size.width - 510, editedImageResized.size.height - 30, 500, 20);

        // clean up

        editedImageResized = nil;
        [editedImageResized release];

        // make the label

        UILabel *timeLabel = [[UILabel alloc] initWithFrame:thisRect];
        timeLabel.textAlignment =  UITextAlignmentRight;
        timeLabel.textColor = [UIColor yellowColor];
        timeLabel.backgroundColor = [UIColor clearColor];
        timeLabel.font = [UIFont fontWithName:@"Arial Rounded MT Bold" size:(25.0)];
        timeLabel.text = [self getTodaysDateDatabaseFormat];
        [timestampedImage addSubview:timeLabel];

        // clean up what we won't use any more

        timeLabel = nil;
        [timeLabel release];

        // make UIIMage out of the imageview -- MEMORY LEAK LOOKS LIKE IT IS IN THIS BLOCK

        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

        UIGraphicsBeginImageContextWithOptions(timestampedImage.frame.size, timestampedImage.opaque, [[UIScreen mainScreen] scale]);
        [[timestampedImage layer] renderInContext:UIGraphicsGetCurrentContext()];
        UIImage *finalTimestampImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        timestampedImage.layer.contents = nil;
        CGContextRef context = UIGraphicsGetCurrentContext();
        CGContextRelease(context);

        // clean up the one we won't use any more

        timestampedImage = nil;
        [timestampedImage release];

        // SAVE NORMAL SIZE IMAGE TO DOCUMENTS FOLDER

        NSData *webDataResized = UIImageJPEGRepresentation(finalTimestampImage, 1.0); // JPG

        [webDataResized writeToFile:imagePath atomically:YES];

        // clean up the one we won't use any more

        finalTimestampImage = nil;
        [finalTimestampImage release];

        [pool release]; // to get rid of the context image that is stored

        // SAVE TO DATABASE

        [sqlite executeNonQuery:@"INSERT INTO inspection_images (agentid,groupid,inspectionid,areaid,filename,filenamethumb,filepath,orderid,type) VALUES (?, ?, ?, ?, ?, ?, ?, ?,?) ",
         [NSNumber numberWithInt:loggedIn],
         [NSNumber numberWithInt:loggedInGroup],
         myInspectionID,
         [[tableData objectAtIndex:alertDoMe] objectForKey:@"areaid"],
         fileName,
         fileNameThumb,
         documentsDirectory,
         [NSNumber numberWithInt:photoCount],
         [NSNumber numberWithInt:isPCR]
         ];

        // Clean up

        webDataResized = nil;
        [webDataResized release];

    } else {

        NSLog(@">>> IMAGE ***NOT*** SAVED");

    }

    NSLog(@"IMAGE SAVED - COMPLETE");

    info = nil;
    [info release];

}

推荐答案

你'在释放之前将变量设置为nil，有些已经自动释放。

You're setting your variables to nil before releasing them, and some are already auto released.

通常在使用release时你应该释放它们并将它们设置为nil。

Normally when using release you should release and them set to nil.

[var release]
var = nil;

但在其中一些中你不应该调用release。

But in some of these you should not be calling release.

以下是您的主要罪魁祸首。

The following one is your main culprit.

    // clean up the one we won't use any more

    timestampedImage = nil;
    [timestampedImage release];

    // SAVE NORMAL SIZE IMAGE TO DOCUMENTS FOLDER

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