Observing a KVO compatible model in SwiftUI and MVVM

In model-view-view model (MVVM) architecture the view model observes the model and provides data for the view by transforming it when needed. When the user interacts with the view and changes the data in it then the view model's responsibility is to propagate those mutations back to the model object. Therefore, the important part in …

Validating string in TextField with NumberFormatter in SwiftUI

I was looking into creating a view which has TextField with NumberFormatter. Typed text would show up in a separate label and when trying to enter non-numbers, the TextField would reject those characters. Although TextField component in SwiftUI has generic initialiser init(_:value:formatter:onEditingChanged:onCommit:) it does not seem to do what we need. Value binding does not …

Animating GIFs and APNGs with CGAnimateImageAtURLWithBlock in SwiftUI

This year Apple added CGAnimateImageAtURLWithBlock and CGAnimateImageDataWithBlock for animating GIFs and APNGs on all the platforms to the ImageIO framework. We can pass in URL or data and get callbacks when animation changes the current frame. In Xcode 11 beta 7 implicit bridging to Swift is disabled for those APIs and therefore we need to …