Swift 的四种传值方式: 1.单例 2.代理 3.闭包(oc的block) 4.通知
一、单例
1.创建
class testSwiftView: NSObject {
static let shareInstance = testSwiftView()
func getString(){
print("single")
}
}
2.使用
testSwiftView.shareInstance.getString()
3.验证是否唯一
let obj = testSwiftView.shareInstance
print(Unmanaged.passUnretained(obj).toOpaque()) // 打印内存地址
二、代理
1.定义声明协议
public protocol testDelegate: AnyObject {//必须实现
func changeString(newString: String)
}
extension testDelegate {//可选实现
public func printString(newString: String){}
}
class testSwiftView: UIView {
public weak var delegate: testDelegate?
func testFun(){
self.delegate?.changeString(newString: "hahaha")
}
}
- 遵守协议，实现代理方法
class ViewController: UIViewController, testDelegate {
func changeString(newString: String) {
print(newString)
}
func printString(newString: String) {
print(newString)
}
override func viewDidLoad() {
let obj = testSwiftView()
obj.delegate = self
obj.testFun()
}
}
三、闭包 (即oc的block)
- 定义闭包
typealias swiftBlock = (_ str: String) -> Void
//写法2: typealias swiftBlock = (_ str: String) -> ()
class testSwiftView: UIView {
//闭包：函数参数
func callBackBlock(_ block: @escaping swiftBlock) {
block(_:"闭包传值1")
}
//闭包：变量
var callBack : swiftBlock?
func useBlock(){
if callBack != nil {
callBack!("闭包传值2")
}
}
}
- 使用闭包
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let obj = testSwiftView()
//函数
obj.callBackBlock { (str) in
print(str)
}
//参数
obj.callBack = { (str: String)->Void in
print(str)
return
}
obj.useBlock()
}
}
四、通知
- 添加通知 (用于接收通知,销毁时记得释放添加的通知)
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
//添加通知
NotificationCenter.default.addObserver(self, selector:#selector(test1(notification:)), name: NSNotification.Name("testnotification"), object: nil)
}
//接收通知处理方法
@objc func test1(notification:NSNotification) -> Void {
let userinfo = notification.userInfo as![String:AnyObject]
print("这是个通知:",userinfo["通知"] as!String)
}
//释放移除通知
deinit {
NotificationCenter.default.removeObserver(self)
}
}
2.发出通知
NotificationCenter.default.post(name: NSNotification.Name("testnotification"), object: self, userInfo:["通知":"通知传值"])
