Swift: Cropping a Screenshot without TabBar and NavigationBar

Question

I have a screenshot of the entire screen, screenshot, generated using the following:

let layer = UIApplication.sharedApplication().keyWindow!.l         


        

Answer 1

My answer in Swift 4.2, the steps are in the comments above the code in the function getScreenshot()

@IBAction fileprivate func takeScreenshotButtonTapped(_ sender: UIButton) {

    guard let croppedScreenshotImage = getScreenshot() else { return }

    // do something with the croppedScreenshotImage
}

func getScreenshot() -> UIImage? {

    // 1. get screenshot of the entire screen
    UIGraphicsBeginImageContext(UIApplication.shared.keyWindow!.bounds.size)
    UIApplication.shared.keyWindow!.layer.render(in: UIGraphicsGetCurrentContext()!)
    let screenshot = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    // 2. height of statusBar
    let statusBarHeight = UIApplication.shared.statusBarFrame.size.height

    // 3. height of navigationBar
    var navBarHeight: CGFloat = 0
    if let navigationBarHeight = navigationController?.navigationBar.frame.height {
        navBarHeight = navigationBarHeight
    }

    // 4. total height of statusBar + navigationBar
    let topBarHeight = statusBarHeight + navBarHeight

    // 5. get the height of the tabBar
    var tabBarHeight: CGFloat = 0
    if let tabBarController = tabBarController {
        tabBarHeight = tabBarController.tabBar.frame.size.height
    }

    // 6. to exclude the navigationBar, statusBar, and tabBar from your screenshot start the rect's y-axis at everything below the topBarHeight. For the height subtract the topBarHeight and tabBarHeight from the view's height 
    let rectWithoutNavStatusAndTabBar = CGRect(x: 0, y: topBarHeight, width: self.view.bounds.width, height: self.view.bounds.height - topBarHeight - tabBarHeight)

    guard let safeScreenshot = screenshot else { return nil }

    // 7. crop the screenshot to the rectWithoutNavStatusAndTabBar
    guard let cgImage = safeScreenshot.cgImage?.cropping(to: rectWithoutNavStatusAndTabBar) else { return nil }

    // 8. create an image from the cgImage
    let yourCroppedScreenshotImage = UIImage(cgImage: cgImage)

    return yourCroppedScreenshotImage
}

This is also the Swift 4.2 version of the accepted answer:

func takeScreenshot(sender: AnyObject) {
    let layer = UIApplication.shared.keyWindow!.layer
    let scale = UIScreen.main.scale
    UIGraphicsBeginImageContextWithOptions(layer.frame.size, false, scale);

    layer.render(in: UIGraphicsGetCurrentContext()!)
    let screenshot = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    let croppedImage = self.cropImage(screenshot: screenshot!)
}

func cropImage(screenshot: UIImage) -> UIImage {
    let scale = screenshot.scale
    let imgSize = screenshot.size
    let screenHeight = UIScreen.main.bounds.height
    let bound = self.view.bounds.height
    let navHeight = self.navigationController!.navigationBar.frame.height
    let bottomBarHeight = screenHeight - navHeight - bound
    let crop = CGRect(x: 0, y: 0, width: (imgSize.width - 1) * scale, height: (imgSize.height - bottomBarHeight - 1) * scale)
    let cgImage = screenshot.cgImage?.cropping(to: crop)
    let image: UIImage = UIImage(cgImage: cgImage!)
    return image
}