Swift 3沒有調用的代理函數

Question

我試圖讓我的頭繞過Swift代表，並且偷走了一個Playground，但似乎無法獲得要調用的委託函數。

protocol fBookDelegate:class { 
    func processData(data: String) 
} 

class fBook { 

weak var delegate: fBookDelegate? 

init() { 
    print("initialising fBook") 
    delegate?.processData(data: "hello world") 
    print("we should have printed") 
    } 
} 

class fMain: fBookDelegate { 
init() { 
    print("initialising fMain") 
    let getfBook = fBook() 
    getfBook.delegate = self 
    print("all done let's rumble") 
    } 

func processData(data: String) { 
    print("processing data from fBook with \(data)") 
    } 
} 

var controller = fMain() 

任何人都可以發現我的錯誤嗎？

我得到的輸出是

initialising fMain 
initialising fBook 
we should have printed 
all done let's rumble 

Answer 1

你可以使用這樣的：

import UIKit 
protocol fBookDelegate:class { 
    func processData(data: String) 
} 
class fBook { 
    init(delegate: fBookDelegate?) { 
     print("initialising fBook") 
     delegate?.processData(data: "hello world") 
     print("we should have printed") 
    } 
} 
class fMain: fBookDelegate { 
    init() { 
     print("initialising fMain") 
     let getfBook = fBook(delegate: self) 
     print("all done let's rumble") 
    } 
    func processData(data: String) { 
     print("processing data from fBook with \(data)") 
    } 
} 

var controller = fMain() 

輸出：

initialising fMain 
initialising fBook 
processing data from fBook with hello world 
we should have printed 
all done let's rumble 

Answer 2

下面是使用委託一個選項：

protocol fBookDelegate:class { 
    func processData(data: String) 
} 

class fBook { 

    weak var delegate: fBookDelegate? 

    init() { 
     print("initialising fBook") 
    } 

    func talkToMe() { 
     delegate?.processData(data: "hello world") 
    } 
} 

class fMain: fBookDelegate { 
    init() { 
     print("initialising fMain") 
     let getfBook = fBook() 
     getfBook.delegate = self 
     getfBook.talkToMe() 
     print("all done let's rumble") 
    } 

    func processData(data: String) { 
     print("processing data from fBook with \(data)") 
    } 
} 

var controller = fMain() 

另一種是自定義的初始化方法，它採用的委託作爲參數。