Objective-C: Capture screenshot of all views within custom frame

Question

I have a game where users can create custom levels and upload them to my server for other users to play and I want to get a screenshot of the "action area" before the user tests his/her level to upload to my server as sort of a "preview image".

I know how to get a screenshot of the entire view, but I want to define it to a custom frame. Consider the following image:

I want to just take a screenshot of the area in red, the "action area." Can I achieve this?

Answer 1

Just you need to make a rect of the area you want to be captured and pass the rect in the method.

Swift 3.x :

extension UIView {
  func imageSnapshot() -> UIImage {
    return self.imageSnapshotCroppedToFrame(frame: nil)
  }

  func imageSnapshotCroppedToFrame(frame: CGRect?) -> UIImage {
    let scaleFactor = UIScreen.main.scale
    UIGraphicsBeginImageContextWithOptions(bounds.size, false, scaleFactor)
    self.drawHierarchy(in: bounds, afterScreenUpdates: true)
    var image: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()

    if let frame = frame {
        let scaledRect = frame.applying(CGAffineTransform(scaleX: scaleFactor, y: scaleFactor))

        if let imageRef = image.cgImage!.cropping(to: scaledRect) {
            image = UIImage(cgImage: imageRef)
        }
    }
    return image
  }
}

//How to call :
imgview.image = self.view.imageSnapshotCroppedToFrame(frame: CGRect.init(x: 0, y: 0, width: 320, height: 100))

Objective C :

-(UIImage *)captureScreenInRect:(CGRect)captureFrame 
{
    CALayer *layer;
    layer = self.view.layer;
    UIGraphicsBeginImageContext(self.view.bounds.size); 
    CGContextClipToRect (UIGraphicsGetCurrentContext(),captureFrame);
    [layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *screenImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return screenImage;
}

//How to call :
imgView.image = [self captureScreenInRect:CGRectMake(0, 0, 320, 100)];