seq.forEach()

• ⛔ break : not allowed.

• ⛔ continue : not allowed.

• ❗ return : exit only from the current call to body. 👉 1️

// `seq.forEach(_:)` declaration:
func forEach(
    _ body: (Self.Element) throws -> Void
) rethrows

1

// sequence.forEach()
(1...10).forEach { n in 
    print(n)
    // ⭐️ return from this closure, not from the `forEach` method
    if n > 2 { return } 
}
// 1, 2, ..., 10

2

class ArticleGroupViewController: UIViewController {

    private let articles: [Article]

    override func viewDidLoad() {
        super.viewDidLoad()
        
        // ⭐️ 直接將 method 放入 forEach()，可增加程式的可讀性。
        articles.forEach(addArticleView)
    }

    private func addArticleView(for article: Article) {
        let articleView = ArticleView()
        view.addSubview(articleView)
    }
}

📘 手冊

• Collections ⟩ Sequence ⟩ .forEach(_:)

• Flow Control ⟩ for-in loop - iterate over a sequence (array, range, string, dictionary)

📗 參考

• Advanced Swift, p.

• Sundell ⟩ Picking between a for loop and forEach

👥 相關

• ⟩ for...in ⭐️

forEach vs. for-in loop