Xamarin iOS: Custom back button image is too small-CodePudding

I have a custom UINavigationController and the following code in that controller to provide a custom back button image:

public override void PushViewController(UIViewController viewController, bool animated)
{
     base.PushViewController(viewController, animated);
        
     viewController.NavigationItem.BackButtonDisplayMode = UINavigationItemBackButtonDisplayMode.Minimal;
 }

public override void ViewWillAppear(bool animated)
{
   base.ViewWillAppear(animated);

   SetNeedsStatusBarAppearanceUpdate();
        
   var uiNavigationBarAppearance = new UINavigationBarAppearance();

   // ...
   // configure common UINavigationBarAppearance properties
   // ...

   var img = UIImage.FromBundle("back");
   uiNavigationBarAppearance.SetBackIndicatorImage(img, img);

   NavigationBar.StandardAppearance = uiNavigationBarAppearance;
}

This works fine, but I noticed the back image (which is a PDF asset) is too small compared to NavigationItem.RightBarButtonItems. In fact, if I use the same PDF as a RightBarButtonItem, it will be bigger.

Is it possible to configure the size of the back button image so it looks normal?

P.S. Minimum supported OS version is 15.4.

CodePudding user response：

You could use UIGraphicsImageRenderer to resize the original image , try the following code .

var img = UIImage.FromBundle("back");

var factor = 1.5;   //the value you can control
var newSize = new CoreGraphics.CGSize(factor*img.Size.Width,factor*img.Size.Height);

var renderer = new UIGraphicsImageRenderer(newSize);

var image = renderer.CreateImage((context) => {
    img.Draw(new CoreGraphics.CGRect(0,0,newSize.Width,newSize.Height));
});

uiNavigationBarAppearance.SetBackIndicatorImage(image, image);