Swift'AnyObject'没有名为“make”的成员。 [英] Swift 'AnyObject' does not have a member named "make"

问题描述

我很困惑，如何我可以有两个键作为字符串和一个工作，而另一个不。错误发生在接近结尾的行：

println（这里是（car.year）（car.make）（car.model））

可能导致问题的make变量是什么？

  protocol NSCoding {
 
} 
 
 class Car：NSObject {
 
 var year：Int = 0 
 var make：String = 
 var model：String =
 
 override init（）{
 super.init（）
} 
 
 func encodeWithCoder aCoder：NSCoder！）{
 aCoder.encodeInteger（year，forKey：year）
 aCoder.encodeObject（make，forKey：make）
 aCoder.encodeObject（model，forKey： model）
} 
 
 init（coder aDecoder：NSCoder！）{
 
 super.init（）
 
 year = aDecoder .decodeIntegerForKey（year）
 make = aDecoder.decodeObjectForKey（make）as String 
 model = aDecoder.decodeObjectForKey（model）as String 
 
} 
} 
 
 class CarData {
 
 
 func archive（）{
 var documentDirectories：NSArray 
 var documentDirectory：String 
 var path：String 
 var unarchivedCars：NSArray 
 var allCars：NSArray 
 
 //创建用于归档的文件路径。 
 documentDirectories = NSSearchPathForDirectoriesInDomains（.DocumentDirectory，.UserDomainMask，true）
 
 //从该列表中获取文档目录
 documentDirectory = documentDirectories.objectAtIndex（0）as String 
 
 //用.archive文件名追加
 path = documentDirectory.stringByAppendingPathComponent（swift_archiver_demo.archive）
 
 var car1：Car！ = Car（）
 var car2：Car！ = Car（）
 var car3：Car！ = Car（）
 
 car1.year = 1957 
 car1.make =Chevrolet
 car1.model =Bel Air
 
 car2。 year = 1964 
 car2.make =Dodge
 car2.model =Polara
 
 car3.year = 1972 
 car3.make =Plymouth
 car3.model =Fury
 
 allCars = [car1，car2，car3] 
 
 //'archiveRootObject：toFile'返回一个指向
 //操作是否成功。我们可以使用它来记录消息。 
 if NSKeyedArchiver.archiveRootObject（allCars，toFile：path）{
 println（Success writing to file！）
} else {
 println（无法写入文件！ ）
} 
 
 //现在可以取消归档数据并将其放入不同的数组，以验证
 //这一切都可以工作。取消归档对象并将它们放入新数组
 unarchivedCars = NSKeyedUnarchiver.unarchiveObjectWithFile（path）as NSArray 
 
 //输出新数组
 for car：AnyObject in unarchivedCars {
 println（这里是一个\（car.year）\（car.make）\（car.model））
} 
} 
 
} 
  

解决方案

在for循环中使用downcasting。编译器需要知道car是Car类型，而不是AnyObject。

  
 println（这里是一个\（car.year）\（car.make）\（car.model））
} 
  pre> 
I am confused on how I can have two keys as strings and one works and the other doesn't.  Error occurs in the line near the end:

println("Here's a (car.year) (car.make) (car.model)")

What is it about the "make" variable that could be causing the problem?
protocol NSCoding {

}

class Car:NSObject {

    var year: Int = 0
    var make: String = ""
    var model: String = ""

    override init() {
        super.init()
    }

    func encodeWithCoder(aCoder: NSCoder!) {
        aCoder.encodeInteger(year, forKey:"year")
        aCoder.encodeObject(make, forKey:"make")
        aCoder.encodeObject(model, forKey:"model")
    }

    init(coder aDecoder: NSCoder!) {

        super.init()

        year = aDecoder.decodeIntegerForKey("year")
        make = aDecoder.decodeObjectForKey("make") as String
        model = aDecoder.decodeObjectForKey("model") as String

    }
}

class CarData {


    func archiveData () {
        var documentDirectories:NSArray
        var documentDirectory:String
        var path:String
        var unarchivedCars:NSArray
        var allCars:NSArray

        // Create a filepath for archiving.
        documentDirectories = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)

        // Get document directory from that list
        documentDirectory = documentDirectories.objectAtIndex(0) as String

        // append with the .archive file name
        path = documentDirectory.stringByAppendingPathComponent("swift_archiver_demo.archive")

        var car1:Car! = Car()
        var car2:Car! = Car()
        var car3:Car! = Car()

        car1.year = 1957
        car1.make = "Chevrolet"
        car1.model = "Bel Air"

        car2.year = 1964
        car2.make = "Dodge"
        car2.model = "Polara"

        car3.year = 1972
        car3.make = "Plymouth"
        car3.model = "Fury"

        allCars = [car1, car2, car3]

        // The 'archiveRootObject:toFile' returns a bool indicating
        // whether or not the operation was successful. We can use that to log a message.
        if NSKeyedArchiver.archiveRootObject(allCars, toFile: path) {
            println("Success writing to file!")
        } else {
            println("Unable to write to file!")
        }

        // Now lets unarchive the data and put it into a different array to verify
        // that this all works. Unarchive the objects and put them in a new array
        unarchivedCars = NSKeyedUnarchiver.unarchiveObjectWithFile(path) as NSArray

        // Output the new array
        for car : AnyObject in unarchivedCars {
            println("Here's a \(car.year) \(car.make) \(car.model)")
        }
    }

}

解决方案
Use downcasting in your for loop. The compiler needs to know that car is of type Car and not just AnyObject.
for car in cars as [Car!] {
    println("Here's a \(car.year) \(car.make) \(car.model)")
}


                        
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