Swift API design questions

Official Swift API design Specification

1. Explain why the first method declares the parameter label at and the second method defaults.

extension List {
  public mutating func remove(at position: Index) -> Element
  public mutating func remove(_ member: Element) -> Element?
}
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2. Which of the following two statements is correct and explain why.

func add(_ observer: NSObject, for keyPath: String)
func addObserver(_ observer: NSObject, forKeyPath path: String)
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3. Which of the following statements is better, and why?

x.subViews(havingColor: y)
x.subViews(color: y)
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4. Which of the following statements is better, and why?

let foreground = Color(red: 32, green: 64, blue: 128)
let foreground = Color(havingRGBValuesRed: 32, green: 64, andBlue: 128)
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5. What is the difference between the following two methods?

x.sort()
x.sorted()
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6. ProtocolWhat are the naming rules?
7. When can global functions be declared?
8. Why does the method declared below default the first parameter label?

extension Shape {
  /// Returns `true` iff `other` is within the area of `self`.
  func contains(_ other: Point) -> Bool{... }/// Returns `true` iff `other` is entirely within the area of `self`.
  func contains(_ other: Shape) -> Bool{... }}Copy the code

9. What is the problem with the following statement?

extension Box {
  /// Returns the `Int` stored in `self`, if any, and
  /// `nil` otherwise.
  func value(a) -> Int? {... }/// Returns the `String` stored in `self`, if any, and
  /// `nil` otherwise.
  func value(a) -> String? {... }}Copy the code

10. Which of the following parameter names is better?

func filter(_ predicate: (Element) -> Bool) - > [Generator.Element]
func filter(_ includedInResult: (Element) -> Bool) - > [Generator.Element]
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11. Where is the error declared below?

extension String {
/ / /... description...
	public func compare(_ options: CompareOptions = [], other: String, range: Range? = nil, locale: Locale? = nil
	) -> Ordering
}
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12. Why don’t the following functions declare parameter labels?

min(number1, number2)
zip(sequence1, sequence2)
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13. Why does one of the following two initialization methods have a parameter label and one does not?

extension UInt32 {
/// Creates an instance having the specified value.
init(_ value: Int16)           
/// Creates an instance having the lowest 32 bits of source.
init(truncating source: UInt64)}Copy the code

14. Which of the following method declarations is better?

// A moves to a certain point
a.move(toX: b, y: c)
a.moveTo(x: b, y: c)
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15. Which of the following method declarations is better?

extension UIView {
	func addSubview(_ view: UIView)
	func add(subview: UIView)
}
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16. What problems might arise from the following statement?

struct Array {
  /// Inserts `newElement` at `self.endIndex`.
  public mutating func append(_ newElement: Element)

  /// Inserts the contents of `newElements`, in order, at
  /// `self.endIndex`.
  public mutating func append(_ newElements: S)
    where S.Generator.Element= =Element
}
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17. Which of the following names is correct:

struct Model {
	var sourceURL: URL
	var sourceUrl: URL
}
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Comprehensive problem

• When is the default parameter label for the first argument to a method or function?