Swift 的四種傳值方式: 1.單例 2.代理 3.閉包(oc的block) 4.通知

一室叉、單例

1.創(chuàng)建

class testSwiftView: NSObject {
    static let shareInstance = testSwiftView()
    func getString(){
        print("single")
    }
}

2.使用

testSwiftView.shareInstance.getString()

3.驗證是否唯一

let obj = testSwiftView.shareInstance
print(Unmanaged.passUnretained(obj).toOpaque()) // 打印內(nèi)存地址

二趋箩、代理

1.定義聲明協(xié)議

public protocol testDelegate: AnyObject {//必須實現(xiàn)
    func changeString(newString: String)
}
extension testDelegate {//可選實現(xiàn)
    public func printString(newString: String){}
}

class testSwiftView: UIView {
    public weak var delegate: testDelegate?
    func testFun(){
        self.delegate?.changeString(newString: "hahaha")
    }
}

2. 遵守協(xié)議泣懊，實現(xiàn)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、閉包 (即oc的block)

1. 定義閉包

typealias swiftBlock = (_ str: String) -> Void
//寫法2: typealias swiftBlock = (_ str: String) -> ()
class testSwiftView: UIView {
    //閉包：函數(shù)參數(shù)
    func callBackBlock(_ block: @escaping swiftBlock) {
        block(_:"閉包傳值1")
    }
    
    //閉包：變量
    var callBack : swiftBlock?
    func useBlock(){
        if callBack != nil {
            callBack!("閉包傳值2")
        }
    }
}

2. 使用閉包

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let obj = testSwiftView()
        
        //函數(shù)
        obj.callBackBlock { (str) in
            print(str)
        }
        
        //參數(shù)
        obj.callBack = { (str: String)->Void in
            print(str)
            return
        }
        obj.useBlock()
    }
}

四、通知

1. 添加通知 (用于接收通知,銷毀時記得釋放添加的通知)

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)
    }
    
    //接收通知處理方法
    @objc func test1(notification:NSNotification) -> Void {
           let userinfo = notification.userInfo as![String:AnyObject]
           
           print("這是個通知:",userinfo["通知"] as!String)
       }
    //釋放移除通知
    deinit {
           NotificationCenter.default.removeObserver(self)
    }
    
}

2.發(fā)出通知

NotificationCenter.default.post(name: NSNotification.Name("testnotification"), object: self, userInfo:["通知":"通知傳值"])