Swift Optionals Crash Course
Optionals are notated by a “?” postfix. Some types are optional by default. If a type is optional, it either has a value, or is nil. There are a lot of things that are optionals, such as images and text fields. Optionals allow for more logical API’s
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var age: Int? //Custom optional. Since it is optional, it does not need to be instantiated inside a class. It can be assigned to later.
let image: UIImage = UIImage(named: “profilePic”) //Type will be optional by default
let textField: UITextField = UITextField() //Type will be optional by default
//Optional values have to be “un-wrapped” to be used, because something can’t both have a value and be nil.
//There are multiple ways to un-wrap an optional
////SAFE METHODS:
if let text = textField.text {
//“text” will be accessible inside here if it exists
}
guard let text = textField.text else { return } //text will be available following declaration
let text = textField.text ?? “” //If textField is nil, “” will be given as a default value
////UNSAFE METHODS:
let text = textField.text! //This will crash if the optional is nil. You should only use this if you know the value will never be nil.
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Originally published 04/06/2021 @ https://pittcsc.org/ Discord
Published here on 09/08/2022. Blog published date reflects the original date of publication.
