UIScrollView 스크린샷 만들기

네이티브 UIScrollView 화면에서 스크린샷 구하는 방법에 대해 알아보자.

일반적으로 스크린샷을 구해보면 화면에 보이는 부분만

구해지며 숨겨진 영역은 흰색화면으로 출력된다. (iOS 13.0이상 에서 생기는 버그)

extension UIScrollView {
    func screenshot() -> UIImage? {
        UIGraphicsBeginImageContextWithOptions(contentSize, false, 0.0)
        let savedContentOffset = contentOffset
        let savedFrame = frame
        defer {
            UIGraphicsEndImageContext()
            contentOffset = savedContentOffset
            frame = savedFrame
        }
        contentOffset = .zero
        frame = CGRect(x: 0, y: 0, width: contentSize.width, height: contentSize.height)
        guard let ctx = UIGraphicsGetCurrentContext() else {
            return nil
        }
        layer.render(in: ctx)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        return image
    }
}

이를 위해 UIScrollView를 부모로 부터 Layout 컨텐츠를 비활성하고 스크린샷 이미지를 구하고 다시

원래대로 활성화 시켜주는 방법으로 해결 가능하다.

extension UIScrollView {
    func screenshot() -> UIImage? {
        UIGraphicsBeginImageContextWithOptions(contentSize, false, 0.0)
        let savedContentOffset = contentOffset
        let actualConstraints = relatedConstraints()
        NSLayoutConstraint.deactivate(actualConstraints)
        translatesAutoresizingMaskIntoConstraints = true
        frame = CGRect(x: 0, y: 0, width: contentSize.width, height: contentSize.height)
        contentOffset = .zero
        defer {
            UIGraphicsEndImageContext()
            translatesAutoresizingMaskIntoConstraints = false
            NSLayoutConstraint.activate(actualConstraints)
            superview?.layoutIfNeeded()
            contentOffset = savedContentOffset
        }
        guard let ctx = UIGraphicsGetCurrentContext() else {
            return nil
        }
        layer.render(in: ctx)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        return image
    }
}


extension UIView {
    func relatedConstraints() -> [NSLayoutConstraint] {
        var constraints = self.constraints
        var parent = superview
        while parent != nil {
            constraints.append(contentsOf: parent!.constraints.filter { $0.firstItem === self || $0.secondItem === self })
            parent = parent!.superview
        }
        return constraints
    }
    
    class func getAllSubviews<T: UIView>(from parenView: UIView) -> [T] {
        return parenView.subviews.flatMap { subView -> [T] in
            var result = getAllSubviews(from: subView) as [T]
            if let view = subView as? T { result.append(view) }
            return result
        }
    }
	
    class func getAllSubviews(from parenView: UIView, types: [UIView.Type]) -> [UIView] {
        return parenView.subviews.flatMap { subView -> [UIView] in
            var result = getAllSubviews(from: subView) as [UIView]
            for type in types {
                if subView.classForCoder == type {
                    result.append(subView)
                    return result
                }
            }
            return result
        }
    }
	
    func getAllSubviews<T: UIView>() -> [T] { return UIView.getAllSubviews(from: self) as [T] }
    func get<T: UIView>(all type: T.Type) -> [T] { return UIView.getAllSubviews(from: self) as [T] }
    func get(all types: [UIView.Type]) -> [UIView] { return UIView.getAllSubviews(from: self, types: types) }
}


/*
// 현재 뷰의 하위뷰 중 UIScrollView를 구한다.
if let scrollView = self.view.get(all: UIScrollView.self).first {
    // 스크롤뷰의 모든 컨텐츠가 나오도록 스크린샷 이미지로 반환한다.
    let image = scrollView.screenshot()
    
    // 주어진 이미지를 공유
    DispatchQueue.main.async {
        let imageToShare = [ image ]
        let activityVC = UIActivityViewController(activityItems: imageToShare as [Any], applicationActivities: nil)
        self.present(activityVC, animated: true, completion: nil)
    }
}
*/