My aim is to create custom image for MKAnnotationView.

The number of "service items" in image can be different for every annotation -> it should be possible to dynamically change items in view.

My idea was to create custom UIView (xib), load xib programmatically and change items dynamically. Then I would convert UIView to UIImage.

//ServiceAnnotationView.xib

//ServiceAnnotationView.class
class ServiceAnnotationView: UIView{
    
}

//extension UIView -> possible to load xib file from code

extension UIView {
    class func fromNib<T: UIView>() -> T {
        return Bundle(for: T.self).loadNibNamed(String(describing: T.self), owner: nil, options: nil)![0] as! T
    }

Creating annotation image dynamically.

let view = MKAnnotationView(annotation: annotation, reuseIdentifier: identifier)
let serviceAnnotationView: ServiceAnnotationView = ServiceAnnotationView.fromNib()
view.image = serviceAnnotationView.asImage()

Result when showing 2 items:

Result when showing 1 items

In this case the UIView should automatically shrink. The width of UIView is always the same. No matter how many items are present in UIStackView.

What I have tried so far? I was trying to specify frame for UIView based on number of items. -> no success

Then I was changing constraint size of UIView based on number of items. -> no success

The UIView should automatically resize due to UIStackView. Why in this case is not happening?

CodePudding user response：

You've left out a lot of information about your setup and how you're actually trying to use this, but this might help...

Assuming you have:

• some var/func in your ServiceAnnotationView to show/hide the images in the stack view
• you have a working UIView extension for .asImage()
• you've set sizing constraints on the images (e.g. Height and Width)

Call .setNeedsLayout() and .layoutIfNeeded() before calling .asImage():

    let serviceAnnotationView: ServiceAnnotationView = ServiceAnnotationView.fromNib()

    // however you're setting the number of images to show in the stack view        
    serviceAnnotationView.numItems = 3
    
    serviceAnnotationView.translatesAutoresizingMaskIntoConstraints = false
    
    serviceAnnotationView.setNeedsLayout()
    serviceAnnotationView.layoutIfNeeded()
    
    let img = serviceAnnotationView.asImage()