Adding Swift Initializers Through Extensions

While watching the Stack Views with Enums by objc.io, I learned an interesting little tidbit. You can add a convenience constructor aka convenience initializer by extending a class. The benefit of doing such is that you don’t have to subclass the class. In hindsight, the availability of that feature seems obvious. The Swift reference even has a section called “Initializers”. However, this ability may be news to others as well.

Similar to what they show at 7:45 in the video, one can write the following:

extension UIStackView {
    
    convenience init(labelTitles: [String]) {
        self.init()
        
        for title in labelTitles {
            let label = UILabel()
            label.text = title
            addArrangedSubview(label)
        }
    }
}

extension UIStackView {

convenience init(labelTitles: [String]) {

self.init()

for title in labelTitles {

let label = UILabel()

label.text = title

addArrangedSubview(label)

}

Next, you can call this new init like any other initializer:

let stackView = UIStackView(labelTitles: ["Harry Potter", "Star Trek"])

1	let stackView = UIStackView(labelTitles: ["Harry Potter", "Star Trek"])

I highly recommend you watch the entire Stack Views with Enums video. Enjoy!