2018年新的開始免钻，好好的整理一下Swift知識(shí)點(diǎn)彼水，希望在整理過程中提升自己。

1.swift 4.0 取消了 Selector("cyanButtonClick") 這種寫法.

class ViewController: UIViewController {

    @IBOutlet weak var buttonA: UIButton!

     override func viewDidLoad() {
        super.viewDidLoad()
        //錯(cuò)誤寫法
         buttonA.addTarget(self,
                          action: Selector("buttonActionA"),
                          for: .touchUpInside)
         //正確寫法
         buttonA.addTarget(self,
                          action: NSSelectorFromString("buttonActionA"),
                          for: .touchUpInside)
    }

    func buttonActionA(){
        print("text for selector")
    }
//以上寫法已經(jīng)被swift4.0取消极舔，如果繼續(xù)使用會(huì)被報(bào)“Use '#selector' instead of explicitly constructing a 'Selector' "

2.我們在開發(fā)過程中通常會(huì)這樣寫凤覆，坦率的講這樣寫沒什么問題，但是不夠優(yōu)雅

class ViewController: UIViewController {
    @IBOutlet weak var buttonA: UIButton!
     override func viewDidLoad() {
        super.viewDidLoad()
        //防止方法名重復(fù)拆魏，在方法前面跟上所在類以區(qū)別
       buttonA.addTarget(self,
                          action: #selector(ViewController.buttonActionA),
                          for: .touchUpInside)
    }

    func buttonActionA(){
        print("text for selector")
    }

3.如何訪問我們的private私有方法盯桦，則是在前面加@Objc變成運(yùn)行時(shí)澡绩。

class ViewController: UIViewController {
    @IBOutlet weak var buttonA: UIButton!
     override func viewDidLoad() {
        super.viewDidLoad()
        //當(dāng)然如果不需要區(qū)分則可以去掉ViewController，也可以用self代替ViewController
        let methodObjc = #selector(ViewController.buttonActionObjc)
        buttonA.addTarget(self,
                          action: methodObjc,
                          for: .touchUpInside)

    }

    func buttonActionObjc(){
        print("text for selectorObjc")
    }

4.相同方法名不同參數(shù)俺附，可以用 as 區(qū)分

class ViewController: UIViewController {
    @IBOutlet weak var buttonA: UIButton!
    @IBOutlet weak var buttonB: UIButton!
     override func viewDidLoad() {
        super.viewDidLoad()

      let methodA = #selector(buttonActionA as () -> ())
      let methodB = #selector(buttonActionB as (UIButton) -> ())
        
       buttonA.addTarget(self,
                             action: methodA,
                             for: .touchUpInside)
        buttonB.addTarget(self,
                                    action: methodB,
                                    for: .touchUpInside)
    }

    func buttonActionA(){
        print("text for buttonActionA")
    }

    func buttonActionB(){
        print("text for buttonActionB")
    }

5.Swift 3.0 中加入了 Selector 引用變量（不可為常量）的 getter 和 setter 方法：

相關(guān)鏈接：https://github.com/apple/swift-evolution/blob/master/proposals/0064-property-selectors.md
一直在找使用場景：a.可以判斷屬性是否包含getter 和 setter。  b.可以結(jié)合responds方法使用溪掀。
class Person: NSObject {
    dynamic var firstName: String
    dynamic let lastName: String
    dynamic var fullName: String {
        return "\(firstName) \(lastName)"
    }
    
    init(firstName: String, lastName: String) {
        self.firstName = firstName
        self.lastName = lastName
    }
}
let firstNameGetter = #selector(getter: Person.firstName)
let firstNameSetter = #selector(setter: Person.firstName)

6.比較優(yōu)雅的寫法可以把Selector定義成extension事镣，包含所有定義的selector

extension Selector {

    static let methodA = #selector(ViewController.buttonActionA)

}

class ViewController: UIViewController {
    @IBOutlet weak var buttonA: UIButton!
     override func viewDidLoad() {
        super.viewDidLoad()

        buttonA.addTarget(self,
                          action: .methodA,
                          for: .touchUpInside)
    }

    func buttonActionA(){
        print("text for selector")
    }