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 …

Creating a pre-push git hook in Swift script

Git hooks are scripts written in any scripting language and are triggered when important actions occur. Hooks are stored in the repository‚Äôs .git/hooks folder. The script needs to have an appropriate filename without a path extension and also have executable permissions. Push event is an excellent time for triggering unit-tests and making sure local changes …

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 …

Adding custom attribute to NSAttributedString on iOS

NSAttributedString is used for displaying rich text on Apple platforms. There are many attributes available for styling the text. Let's see how to add new attribute and how to draw it in UITextView. Drawing custom attribute Defining a new attribute is just a matter of extending NSAttributedString.Key and defining a new static variable. Difficult part …

Persistent reusable container for item collections in Swift

Let's build a container where we can store collections of items conforming to a protocol. All the collections are identified by a case in enum. For making the container reusable, we'll use protocols as requirements on keys and items in collections. Moreover, the container should be archivable and unarchivable. Creating a reusable container Container's implementation …