ios - 无法分配给属性 'observationTime' 是一个只读属性

Question

尝试将 observationTime 设置为时间间隔时出现此错误。不知道为什么我可以设置一个属性，我在其他地方都是这样设置的

weatherReading?.observationTime = NSTimeIntervalSince1970

@objcMembers class WeatherThirdPartyReadings: NSObject  {

    private var _temperature: Double
    private var _speed: Double
    private var _direction: Double
    private var _observationTime: Double
    private var _isSummaryLoaded: Bool

    var temperature: Double {
        return _temperature
    }
    var speed: Double {
        return _speed
    }
    var direction: Double {
        return _direction
    }
    var observationTime: Double {
        return _observationTime
    }
    var isSummaryLoaded: Bool {
        return _isSummaryLoaded
    }

    init(temperature: Double, speed: Double, direction: Double, observationTime: Double, isSummaryLoaded: Bool) {
        self._temperature = temperature
        self._speed = speed
        self._direction = direction
        self._observationTime = observationTime
        self._isSummaryLoaded = isSummaryLoaded
    }
}

Answer 1

你需要

var observationTime: Double { 
    set { 
        _observationTime = newValue
    }
    get{ 
        return _observationTime
    }
}

像这样

var observationTime: Double {
    return _observationTime
}

使它成为只读属性，get

的默认实现

---

@objcMembers class WeatherThirdPartyReadings: NSObject  {

    var temperature: Double
    var speed: Double
    var direction: Double
    var observationTime: Double
    var isSummaryLoaded: Bool

    init(temperature: Double, speed: Double, direction: Double, observationTime: Double, isSummaryLoaded: Bool) {
        self.temperature = temperature
        self.speed = speed
        self.direction = direction
        self.observationTime = observationTime
        self.isSummaryLoaded = isSummaryLoaded
    }
}