How do I create a Navigation Bar that has a left and right button on a ViewController that is not the root Viewcontroller? - ios

Question

This is how I want it to look. I've tried to use this code:
let button = UIButton.init(type: .custom)
button.setImage(UIImage.init(named: "yourImageName.png"), for: UIControlState.normal)
button.addTarget(self, action:#selector(ViewController.callMethod), for:.touchUpInside)
button.frame = CGRect.init(x: 0, y: 0, width: 30, height: 30)
//CGRectMake(0, 0, 30, 30)
let barButton = UIBarButtonItem.init(customView: button)
self.navigationItem.leftBarButtonItem = barButton
However, when I create the Navigation Controller, I make my map view(the main screen) the root viewcontroller for the Nav Controller. Thus, the view will not have a default back button, since there are no views on the stack before it. Is there a way to override this so my image shows up for the left button? The code above does not produce an image for the left button successfully. It's blank.

Answer 1

Figured out the answer:
var image = UIImage(named: "ic-menu-48px.png")
let navCon = self.navigationController
image = self.resizeImage(image: image!, targetSize: CGSize(width: 25.0,height: 25.0))
image = image?.withRenderingMode(.alwaysOriginal)
self.navigationItem.leftBarButtonItem = UIBarButtonItem(image: image, style:.plain, target: nil, action: nil)
func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
let size = image.size
let widthRatio = targetSize.width / size.width
let heightRatio = targetSize.height / size.height
// Figure out what our orientation is, and use that to form the rectangle
var newSize: CGSize
if(widthRatio > heightRatio) {
newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
} else {
newSize = CGSize(width: size.width * widthRatio, height: size.height * widthRatio)
}
// This is the rect that we've calculated out and this is what is actually used below
let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)
// Actually do the resizing to the rect using the ImageContext stuff
UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
image.draw(in: rect)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}