2018年新的开始，好好的整理一下Swift知识点，希望在整理过程中提升自己。
1.swift 4.0 取消了 Selector("cyanButtonClick") 这种写法.
class ViewController: UIViewController {
@IBOutlet weak var buttonA: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
//错误写法
buttonA.addTarget(self,
action: Selector("buttonActionA"),
for: .touchUpInside)
//正确写法
buttonA.addTarget(self,
action: NSSelectorFromString("buttonActionA"),
for: .touchUpInside)
}
func buttonActionA(){
print("text for selector")
}
//以上写法已经被swift4.0取消，如果继续使用会被报“Use '#selector' instead of explicitly constructing a 'Selector' "
2.我们在开发过程中通常会这样写，坦率的讲这样写没什么问题，但是不够优雅
class ViewController: UIViewController {
@IBOutlet weak var buttonA: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
//防止方法名重复，在方法前面跟上所在类以区别
buttonA.addTarget(self,
action: #selector(ViewController.buttonActionA),
for: .touchUpInside)
}
func buttonActionA(){
print("text for selector")
}
3.如何访问我们的private私有方法，则是在前面加@Objc变成运行时。
class ViewController: UIViewController {
@IBOutlet weak var buttonA: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
//当然如果不需要区分则可以去掉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.相同方法名不同参数，可以用 as 区分
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 引用变量（不可为常量）的 getter 和 setter 方法：
相关链接：https://github.com/apple/swift-evolution/blob/master/proposals/0064-property-selectors.md
一直在找使用场景：a.可以判断属性是否包含getter 和 setter。 b.可以结合responds方法使用。
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.比较优雅的写法可以把Selector定义成extension，包含所有定义的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")
}
