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[英]Static func to generate random type in enum causes crash with error “unexpectedly found nil when unwrapping an Optional value”
[英]aDecoder crash when try to fetch nil value also encoding decoding enum values not working
我有一個具有某些屬性的類,並且在保存時使用了編碼,而在提取時使用了解碼器,但是某些數據不是可選的,但是在我第一次獲取它為null時,所以當解碼器正在調用並且發現nill時值會使應用程序崩潰。
所以我想要的是當我獲取數據時,如果沒有找到數據,我可以設置一些默認值而不是崩潰,我可以通過將這些屬性設置為可選來解決此問題,但我不希望這樣做。 並且也無法添加try catch以確保它不會崩潰
請告訴我應該對此類進行哪些更改,並分享一些示例或鏈接或教程,以深入地解釋有關編碼器和解碼器的所有內容(而不是僅提供概述的中等文章)
我是Swift的新手,因此,如果您發現本課有任何問題,請在評論中告訴您最新的Swift的最佳做法。
import Foundation
enum AcModeType {
case acModeCool
case acModeDry
case acModeHeat
case acModeFan
case acModeTimer
}
enum FanModeType {
case fanModeLow
case fanModeMid
case fanModeHigh
case FanModeAuto
}
class AcDevice: Device {
var brandId: String?
var variant: String?
var brandName: String?
var acTemperature: Int = 16
var acMinTemperature: Int = 16
var acMaxTemperature: Int = 32
var weatherTemperature: Int = 0
var roomTemperature: Int = 0
var timeTable = [TimeTable]()
var currentAcMode: AcModeType = .acModeCool
var currentFanMode: FanModeType = .fanModeLow
var lastPowerOnTime: Double = 0.0
var isPowerOn = false
var isSleepOn = false
var isTimeTableOn = false
var hasScreen = false
required public init?(coder aDecoder: NSCoder) {
super.init();
brandId = (aDecoder.decodeObject(forKey: "brandId") as! String?)
variant = (aDecoder.decodeObject(forKey: "variant") as! String?)
brandName = (aDecoder.decodeObject(forKey: "brandName") as! String?)
acTemperature = (aDecoder.decodeObject(forKey: "temperature") as! Int)
acMinTemperature = (aDecoder.decodeObject(forKey: "acMinTemperature") as! Int )
acMaxTemperature = (aDecoder.decodeObject(forKey: "acMaxTemperature") as! Int )
weatherTemperature = (aDecoder.decodeObject(forKey: "weatherTemperature") as! Int)
roomTemperature = (aDecoder.decodeObject(forKey: "roomTemperature") as! Int )
currentAcMode = (aDecoder.decodeObject(forKey: "currentAcMode") as! AcModeType)
currentFanMode = (aDecoder.decodeObject(forKey: "currentFanMode") as! FanModeType)
lastPowerOnTime = (aDecoder.decodeObject(forKey: "lastPowerOnTime") as! Double)
if let timeTable = aDecoder.decodeObject(forKey: "timeTable") as! [TimeTable]? {self.timeTable=timeTable}
}
public override func encode(with aCoder: NSCoder) {
aCoder.encode(self.brandId, forKey: "brandId")
aCoder.encode(self.variant, forKey: "variant")
aCoder.encode(self.brandName, forKey: "brandName")
aCoder.encode(self.acTemperature, forKey: "temperature")
aCoder.encode(self.timeTable, forKey: "timeTable")
aCoder.encode(self.acMinTemperature, forKey: "acMinTemperature")
aCoder.encode(self.acMaxTemperature, forKey: "acMaxTemperature")
aCoder.encode(self.weatherTemperature, forKey: "weatherTemperature")
aCoder.encode(self.roomTemperature, forKey: "roomTemperature")
aCoder.encode(self.currentAcMode, forKey: "currentAcMode")
aCoder.encode(self.currentFanMode, forKey: "currentFanMode")
aCoder.encode(self.lastPowerOnTime, forKey: "lastPowerOnTime")
}
required public init() {
super.init();
brandId = ""
variant = ""
brandName = ""
isPowerOn = false;
isSleepOn = false;
isTimeTableOn = false;
hasScreen = false;
currentAcMode = .acModeCool
acMinTemperature = 16;
acMaxTemperature = 32;
currentFanMode = .fanModeLow
lastPowerOnTime = -1;
timeTable = [TimeTable]()
}
}
在required public init?(coder aDecoder: NSCoder)
您正在使用as!
強制轉換結果的結果decodeObject
,因此,如果應用失敗,則會崩潰。 相反,您可以使用as?
與默認值結合使用以解開可選內容。
例如:
brandId = aDecoder.decodeObject(forKey: "brandId") as? String ?? "your default string"
這使用??
nil合並運算符,當左側為nil時提供默認值。
您可以迅速使用Codable
協議來做到這Codable
。 請看下面的鏈接。
https://hackernoon.com/everything-about-codable-in-swift-4-97d0e18a2999
和,
Apple文檔:
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