ios - 内存警告 UIImagepickerController IOS 7

Question

谁能帮我解决这个问题我对 Objective C 和 iOS 有点陌生。我一直在努力，但我不知道如何解决这个问题，我的应用程序非常简单，它只启动相机拍照并通过电子邮件将它们发送到我们的服务器。此代码在 iOS6 中运行良好。

当我拍照时，我的内存会随着每次屏幕捕获而堆增长，我会收到“收到内存警告”，最后 - 由于内存压力而终止。 -

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

[self.popoverController2 dismissPopoverAnimated:true];
NSString *mediaType = [info
                       objectForKey:UIImagePickerControllerMediaType];

if ([mediaType isEqualToString:(NSString *)kUTTypeImage]) {
    _image = [info
                      objectForKey:UIImagePickerControllerOriginalImage];

   _image = [self fixrotation:_image]; //<----- increased memory when UIImageWriteToSavedPhotosAlbum is uncommented IF is comment it doesn't increased memory but after some pictures I start to get "Received Memory Warning" message until the app Crash.

    if (_newMedia){
       UIImageWriteToSavedPhotosAlbum(_image,
                                       self,@selector(image:finishedSavingWithError:contextInfo:),
                                       nil);
    [self dismissViewControllerAnimated:NO completion:nil];
    [self performSegueWithIdentifier:@"SeleccionadoCameraR" sender:self];


    }else{
        [self performSegueWithIdentifier:@"SeleccionadoCameraR" sender:self];

    }

}

}

- (UIImage *)fixrotation:(UIImage *)image{


if (image.imageOrientation == UIImageOrientationUp) return image;
CGAffineTransform transform = CGAffineTransformIdentity;

switch (image.imageOrientation) {
    case UIImageOrientationDown:
    case UIImageOrientationDownMirrored:
        transform = CGAffineTransformTranslate(transform, image.size.width, image.size.height);
        transform = CGAffineTransformRotate(transform, M_PI);
        break;

    case UIImageOrientationLeft:
    case UIImageOrientationLeftMirrored:
        transform = CGAffineTransformTranslate(transform, image.size.width, 0);
        transform = CGAffineTransformRotate(transform, M_PI_2);
        break;

    case UIImageOrientationRight:
    case UIImageOrientationRightMirrored:
        transform = CGAffineTransformTranslate(transform, 0, image.size.height);
        transform = CGAffineTransformRotate(transform, -M_PI_2);
        break;
    case UIImageOrientationUp:
    case UIImageOrientationUpMirrored:
        break;
}

switch (image.imageOrientation) {
    case UIImageOrientationUpMirrored:
    case UIImageOrientationDownMirrored:
        transform = CGAffineTransformTranslate(transform, image.size.width, 0);
        transform = CGAffineTransformScale(transform, -1, 1);
        break;

    case UIImageOrientationLeftMirrored:
    case UIImageOrientationRightMirrored:
        transform = CGAffineTransformTranslate(transform, image.size.height, 0);
        transform = CGAffineTransformScale(transform, -1, 1);
        break;
    case UIImageOrientationUp:
    case UIImageOrientationDown:
    case UIImageOrientationLeft:
    case UIImageOrientationRight:
        break;
}

// Now we draw the underlying CGImage into a new context, applying the transform
// calculated above.
CGContextRef ctx = CGBitmapContextCreate(NULL, image.size.width, image.size.height,
                                         CGImageGetBitsPerComponent(image.CGImage), 0,
                                         CGImageGetColorSpace(image.CGImage),
                                         CGImageGetBitmapInfo(image.CGImage));


CGContextConcatCTM(ctx, transform);
switch (image.imageOrientation) {
    case UIImageOrientationLeft:
    case UIImageOrientationLeftMirrored:
    case UIImageOrientationRight:
    case UIImageOrientationRightMirrored:
        // Grr...
        CGContextDrawImage(ctx, CGRectMake(0,0,image.size.height,image.size.width), image.CGImage);
        break;

    default:
        CGContextDrawImage(ctx, CGRectMake(0,0,image.size.width,image.size.height), image.CGImage); //when I use instruments it shows that My VM is because of this 
        break;
}

// And now we just create a new UIImage from the drawing context
CGImageRef cgimg = CGBitmapContextCreateImage(ctx);//also this line in Instruments
UIImage *img = [UIImage imageWithCGImage:cgimg];


CGContextRelease(ctx);
CGImageRelease(cgimg);


return img;


 }

大概是内存管理吧。我会感谢你的帮助

Answer 1

您的 fixRotation 方法走在正确的轨道上。但是，您还应该调整图像。否则，图片会很大，大约 30 MB(取决于设备)。

结帐 this blog post关于如何正确调整图像大小。具体来说，你要的UIImage类文件是这些:

UIImage+Resize.h

UIImage+Resize.m

在后台线程上执行此操作也是一个好主意。像这样

- (void)imagePickerController:(UIImagePickerController *)imagePicker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    // Dismiss the image picker first to free its memory
    [self dismissViewControllerAnimated:YES completion:nil];

    UIImage *originalImage = info[UIImagePickerControllerOriginalImage];

    if (!originalImage)
        return;

    // Optionally set a placeholder image here while resizing happens in background

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        // Set desired maximum height and calculate width
        CGFloat height = 640.0f;  // or whatever you need
        CGFloat width = (height / originalImage.size.height) * originalImage.size.width;

        // Resize the image
        UIImage * image = [originalImage resizedImage:CGSizeMake(width, height) interpolationQuality:kCGInterpolationDefault];

        // Optionally save the image here...

        dispatch_async(dispatch_get_main_queue(), ^{
            // ... Set / use the image here...
        });           
    });
}