如何在 init 函数中将委托设置为 self？答案

【问题标题】：How to set delegate to self inside init function?如何在 init 函数中将委托设置为 self？
【发布时间】：2017-02-24 07:26:08
【问题描述】：

我有一个名为 MQTTController 的类，它带有共享实例和私有 init 方法

class MQTTController:NSObject, CocoaMQTTDelegate {
      static let sharedInstance = MQTTController()
      var clientID:String
      var mqtt:CocoaMQTT
      private override init() {
        clientID = "xyz-" + String(ProcessInfo().processIdentifier)
        mqtt = CocoaMQTT(clientID: clientID, host: "mqttcontroller.mqtt.net", port: 1883)
        mqtt.username = "myusername"
        mqtt.password = "mypassword"
        mqtt.willMessage = CocoaMQTTWill(topic: "/will", message: "dieout")
        mqtt.keepAlive = 30
        mqtt.cleanSession = true
        MQTTController.isConnecting = true
        mqtt.delegate = self    //Error at this Line "'self' used before super.init call"
        mqtt.connect()
    } 
}

在这里，我知道我可以创建另一个方法来设置委托并调用mqtt.connect()，但我只想知道是否有任何解决方案，我不必创建和调用另一个方法。

【问题讨论】：

标签： ios swift delegates singleton mqtt

【解决方案1】：

错误信息告诉你需要做什么，你需要在你的init中调用super.init()。

class MQTTController:NSObject, CocoaMQTTDelegate {
    static let sharedInstance = MQTTController()
    var clientID:String
    var mqtt:CocoaMQTT
    private override init() {
        clientID = "xyz-" + String(ProcessInfo().processIdentifier)
        mqtt = CocoaMQTT(clientID: clientID, host: "mqttcontroller.mqtt.net", port: 1883)
        mqtt.username = "myusername"
        mqtt.password = "mypassword"
        mqtt.willMessage = CocoaMQTTWill(topic: "/will", message: "dieout")
        mqtt.keepAlive = 30
        mqtt.cleanSession = true
        MQTTController.isConnecting = true

        super.init() // This line was missing

        mqtt.delegate = self
        mqtt.connect()
    } 
}

【讨论】：

【解决方案2】：

您也应该能够使用defer，但请使用super.init() 答案

class MQTTController:NSObject, CocoaMQTTDelegate {
    static let sharedInstance = MQTTController()
    var clientID:String
    var mqtt:CocoaMQTT
    private override init() {
        clientID = "xyz-" + String(ProcessInfo().processIdentifier)
        mqtt = CocoaMQTT(clientID: clientID, host: "mqttcontroller.mqtt.net", port: 1883)
        mqtt.username = "myusername"
        mqtt.password = "mypassword"
        mqtt.willMessage = CocoaMQTTWill(topic: "/will", message: "dieout")
        mqtt.keepAlive = 30
        mqtt.cleanSession = true
        MQTTController.isConnecting = true

        defer {
            mqtt.delegate = self
            mqtt.connect()
        }
    } 
}

【讨论】：

感谢您的其他选择