Swift编程规范之 Naming

1 Swift中不需要再使用Objective-C那样的前缀，譬如使用 GuybrushThreepwood 而不是LIGuybrushThreepwood。

2 对于类型名即struct, enum, class, typedef, associatedtype等等使用 PascalCase 。

-3 对于函数名、方法名、变量名、常量、参数名等使用camelCase。

4 在使用首字母缩写的时候尽可能地全部大写，并且注意保证全部代码中的统一。不过如果缩写被用于命名的起始，那么就全部小写。

// "HTML" is at the start of a variable name, so we use lowercase "html"
let htmlBodyContent: String = "<p>Hello, World!</p>"
// Prefer using ID to Id
let profileID: Int = 1
// Prefer URLFinder to UrlFinder
class URLFinder {
/* ... */
}

5 对于静态常量使用 k 前缀 + PascalCase。

class MyClassName {
// use `k` prefix for constant primitives
static let kSomeConstantHeight: CGFloat = 80.0
// use `k` prefix for non-primitives as well
static let kDeleteButtonColor = UIColor.redColor()
// don't use `k` prefix for singletons
static let sharedInstance = MyClassName()
/* ... */
}

6 对于泛型或者关联类型，使用PascalCase描述泛型，如果泛型名与其他重复，那么可以添加一个Type后缀名到泛型名上。

class SomeClass<t> { /* ... */ }
class SomeClass<model> { /* ... */ }
protocol Modelable {
associatedtype Model
}
protocol Sequence {
associatedtype IteratorType: Iterator
}</model></t>

7 命名必须要是不模糊的并且方便表述的

// PREFERRED
class RoundAnimatingButton: UIButton { /* ... */ }
// NOT PREFERRED
class CustomButton: UIButton { /* ... */ }

8 不要使用缩写，可以选择较为简短的单词。

// PREFERRED
class RoundAnimatingButton: UIButton {
let animationDuration: NSTimeInterval
func startAnimating() {
let firstSubview = subviews.first
}
}
// NOT PREFERRED
class RoundAnimating: UIButton {
let aniDur: NSTimeInterval
func srtAnmating() {
let v = subviews.first
}
}

9 对于不是很明显的类型需要将类型信息包含在属性名中。

// PREFERRED
class ConnectionTableViewCell: UITableViewCell {
let personImageView: UIImageView
let animationDuration: NSTimeInterval
// it is ok not to include string in the ivar name here because it's obvious
// that it's a string from the property name
let firstName: String
// though not preferred, it is OK to use `Controller` instead of `ViewController`
let popupController: UIViewController
let popupViewController: UIViewController
// when working with a subclass of `UIViewController` such as a table view
// controller, collection view controller, split view controller, etc.,
// fully indicate the type in the name.
let popupTableViewController: UITableViewController
// when working with outlets, make sure to specify the outlet type in the
// variable name.
@IBOutlet weak var submitButton: UIButton!
@IBOutlet weak var emailTextField: UITextField!
@IBOutlet weak var nameLabel: UILabel!
}
// NOT PREFERRED
class ConnectionTableViewCell: UITableViewCell {
// this isn't a `UIImage`, so shouldn't be called image
// use personImageView instead
let personImage: UIImageView
// this isn't a `String`, so it should be `textLabel`
let text: UILabel
// `animation` is not clearly a time interval
// use `animationDuration` or `animationTimeInterval` instead
let animation: NSTimeInterval
// this is not obviously a `String`
// use `transitionText` or `transitionString` instead
let transition: String
// this is a view controller - not a view
let popupView: UIViewController
// as mentioned previously, we don't want to use abbreviations, so don't use
// `VC` instead of `ViewController`
let popupVC: UIViewController
// even though this is still technically a `UIViewController`, this variable
// should indicate that we are working with a *Table* View Controller
let popupViewController: UITableViewController
// for the sake of consistency, we should put the type name at the end of the
// variable name and not at the start
@IBOutlet weak var btnSubmit: UIButton!
@IBOutlet weak var buttonSubmit: UIButton!
// we should always have a type in the variable name when dealing with outlets
// for example, here, we should have `firstNameLabel` instead
@IBOutlet weak var firstName: UILabel!
}

10 在编写函数参数的时候，要保证每个参数都易于理解其功能。

11 根据 Apple’s API Design Guidelines, 对于protocol，如果其描述的是正在做的事情，譬如Collection，那么应该命名为名词。而如果是用于描述某种能力，譬如Equatable, ProgressReporting，那么应该添加 able, ible, 或者 ing 这样的后缀。如果你的协议并不符合上述两种情形，那么应该直接添加一个Protocol后缀，譬如：

// here, the name is a noun that describes what the protocol does
protocol TableViewSectionProvider {
func rowHeight(atRow row: Int) -> CGFloat
var numberOfRows: Int { get }
/* ... */
}
// here, the protocol is a capability, and we name it appropriately
protocol Loggable {
func logCurrentState()
/* ... */
}
// suppose we have an `InputTextView` class, but we also want a protocol
// to generalize some of the functionality - it might be appropriate to
// use the `Protocol` suffix here
protocol InputTextViewProtocol {
func sendTrackingEvent()
func inputText() -> String
/* ... */
}