Swift Style

Mitigating Optional Constipation

Although cascaded bindings avoid Swift’s “pyramids of doom,”^[37] they may lead instead to “constipated blocks of horror.” When faced with excess serial bindings, interleave statements with newlines and comments:

guard
    // Access JSON as dictionary
    let json = json as? NSDictionary,

    // Retrieve results array
    let resultsList = json["results"] as? NSArray,

    // Extract first item
    let results = resultsList.firstObject as? NSDictionary,

    // Extract name and price
    let name = results["trackName"] as? String,
    let price = results["price"] as? NSNumber

else { return nil }

Just because conditions can coexist within a single statement doesn’t mean ...