swift - too - Image for Navigation Bar with Large Title iOS 11




navigation bar title image size (2)

After several hours of coding, I finally managed to make it work. I also decided to write a detailed tutorial: link. Follow it in case you prefer very detailed instructions.

Demo:

Complete project on GitHub: link.

Here are 5 steps to accomplish it:

Step 1: Create an image

private let imageView = UIImageView(image: UIImage(named: "image_name"))

Step 2: Add Constants

/// WARNING: Change these constants according to your project's design
private struct Const {
    /// Image height/width for Large NavBar state
    static let ImageSizeForLargeState: CGFloat = 40
    /// Margin from right anchor of safe area to right anchor of Image
    static let ImageRightMargin: CGFloat = 16
    /// Margin from bottom anchor of NavBar to bottom anchor of Image for Large NavBar state
    static let ImageBottomMarginForLargeState: CGFloat = 12
    /// Margin from bottom anchor of NavBar to bottom anchor of Image for Small NavBar state
    static let ImageBottomMarginForSmallState: CGFloat = 6
    /// Image height/width for Small NavBar state
    static let ImageSizeForSmallState: CGFloat = 32
    /// Height of NavBar for Small state. Usually it's just 44
    static let NavBarHeightSmallState: CGFloat = 44
    /// Height of NavBar for Large state. Usually it's just 96.5 but if you have a custom font for the title, please make sure to edit this value since it changes the height for Large state of NavBar
    static let NavBarHeightLargeState: CGFloat = 96.5
}

Step 3: setup UI:

private func setupUI() {
    navigationController?.navigationBar.prefersLargeTitles = true

    title = "Large Title"

    // Initial setup for image for Large NavBar state since the the screen always has Large NavBar once it gets opened
    guard let navigationBar = self.navigationController?.navigationBar else { return }
    navigationBar.addSubview(imageView)
    imageView.layer.cornerRadius = Const.ImageSizeForLargeState / 2
    imageView.clipsToBounds = true
    imageView.translatesAutoresizingMaskIntoConstraints = false
    NSLayoutConstraint.activate([
        imageView.rightAnchor.constraint(equalTo: navigationBar.rightAnchor,
                                         constant: -Const.ImageRightMargin),
        imageView.bottomAnchor.constraint(equalTo: navigationBar.bottomAnchor,
                                          constant: -Const.ImageBottomMarginForLargeState),
        imageView.heightAnchor.constraint(equalToConstant: Const.ImageSizeForLargeState),
        imageView.widthAnchor.constraint(equalTo: imageView.heightAnchor)
        ])
}

Step 4: create image resizing method

private func moveAndResizeImage(for height: CGFloat) {
    let coeff: CGFloat = {
        let delta = height - Const.NavBarHeightSmallState
        let heightDifferenceBetweenStates = (Const.NavBarHeightLargeState - Const.NavBarHeightSmallState)
        return delta / heightDifferenceBetweenStates
    }()

    let factor = Const.ImageSizeForSmallState / Const.ImageSizeForLargeState

    let scale: CGFloat = {
        let sizeAddendumFactor = coeff * (1.0 - factor)
        return min(1.0, sizeAddendumFactor + factor)
    }()

    // Value of difference between icons for large and small states
    let sizeDiff = Const.ImageSizeForLargeState * (1.0 - factor) // 8.0

    let yTranslation: CGFloat = {
        /// This value = 14. It equals to difference of 12 and 6 (bottom margin for large and small states). Also it adds 8.0 (size difference when the image gets smaller size)
        let maxYTranslation = Const.ImageBottomMarginForLargeState - Const.ImageBottomMarginForSmallState + sizeDiff
        return max(0, min(maxYTranslation, (maxYTranslation - coeff * (Const.ImageBottomMarginForSmallState + sizeDiff))))
    }()

    let xTranslation = max(0, sizeDiff - coeff * sizeDiff)

    imageView.transform = CGAffineTransform.identity
        .scaledBy(x: scale, y: scale)
        .translatedBy(x: xTranslation, y: yTranslation)
}

Step 5:

override func scrollViewDidScroll(_ scrollView: UIScrollView) {
    guard let height = navigationController?.navigationBar.frame.height else { return }
    moveAndResizeImage(for: height)
}

Hope it's clear and helps you! Please let me know in comments if you have any additional questions.

AppStore app has an icon with an image on the right side of the NabBar with Large Title:

Would really appreciate if anyone knows how to implement it or ideas on how to do it.

BTW: Setting an image for UIButton inside of UIBarButtonItem won't work. Tried already. The button sticks to the top of the screen:


Thanks to @TungFam, I think I have a better solution. check it out

two points:

  1. change button frame according to navigation bar height

      // adjust topview height
    override func scrollViewDidScroll(_ scrollView: UIScrollView) {
        guard  let navBar = self.navigationController?.navigationBar else {
            return
        }
        // hardcoded .. to improve
        if navBar.bounds.height > 44 + 40 + 10 {
            NSLayoutConstraint.deactivate(heightConstraint)
            heightConstraint = [topview.heightAnchor.constraint(equalToConstant: 40)]
            NSLayoutConstraint.activate(heightConstraint)
        } else {
            NSLayoutConstraint.deactivate(heightConstraint)
            var  height = navBar.bounds.height - 44 - 10
            if height < 0 {
                height = 0
            }
            heightConstraint = [topview.heightAnchor.constraint(equalToConstant: height)]
            NSLayoutConstraint.activate(heightConstraint)
    
        }
    
    }
  2. change button alpha according to pop/push progress

    @objc func onGesture(sender: UIGestureRecognizer) {
        switch sender.state {
        case .began, .changed:
            if let ct = navigationController?.transitionCoordinator {
                topview.alpha =  ct.percentComplete
            }
        case .cancelled, .ended:
            return
        case .possible, .failed:
            break
        }
    }




large-title