Ios 覆盖和遮罩后的图像未正确定位

我已经在相机上添加了叠加，并从相机上拍摄了相同形状的物体。然后在点击的图像上应用遮罩，这样我将得到该形状的图像，其他区域将为白色。但拍摄的图像和掩蔽后的图像是不一样的。这是最终图像的截图

我想要这张拍摄的照片，上面有星图覆盖的区域

覆盖层 掩蔽

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写一些代码，这样人们可以帮助你。写一些代码，这样人们可以帮助你。

// create view for overlay
CGRect overlayRect = CGRectMake(0, 0, imagePicker.view.frame.size.width, imagePicker.view.frame.size.height-50);
UIView *overlayView = [[UIView alloc] initWithFrame:overlayRect];

// prepare the image to overlay
UIImageView *overlayImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"star"]];
overlayImage.center = overlayView.center;
overlayImage.alpha = 0.6;

[overlayView.layer setOpaque:NO];
overlayView.opaque = NO;
[overlayView addSubview:overlayImage];

imagePicker.cameraOverlayView = overlayView;
[self presentViewController:imagePicker animated:YES completion:nil];

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

    [picker dismissViewControllerAnimated:YES completion:NULL];
    UIImage *mask=[UIImage imageNamed:@"star"];
    UIImage *newimage=[self maskImage:[editingInfo valueForKey:UIImagePickerControllerOriginalImage] withMask:mask];

    [self.imageView setImage:newimage];
    UIImageWriteToSavedPhotosAlbum(newimage, nil, nil, nil);

}