Optionals

Variables must always be defined with an appropriate optionality, following what's described in this blogpost.

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Example

Good

@IBOutlet weak var titleLabel: UILabel!

self.titleLabel.text = "Something"

// If `titleLabel` is `nil`, app will crash at runtime, making it obvious that the developer is forgetting to hook it up in the Interface Builder.

Bad

@IBOutlet weak var titleLabel: UILabel?

if let label = self.titleLabel {
	label.text = "Something"
}

// Conceptually wrong. Developer may forget to hook `titleLabel` in Interface Builder and that mistake could easily make it to a production stage without being noticed.

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Motivation

• It helps catch bugs earlier in the development stage.
• Variables meaning and their intentions are clearer.