从初始化器返回nil之前，必须初始化类实例的所有存储属性. [英] All stored properties of a class instance must be initialized before returning nil from an initializer

问题描述

尽管我不断收到上述消息，但我仍试图在一个类中使用此代码.

I'm trying to use this code in a class though I keep on getting the above message.

    let filePath: NSString!
    let _fileHandle: NSFileHandle!
    let _totalFileLength: CUnsignedLongLong!




init?(filePath: String)
{


    if let fileHandle = NSFileHandle(forReadingAtPath: filePath)
    {

        self.filePath = filePath
        self._fileHandle = NSFileHandle(forReadingAtPath: filePath)
        self._totalFileLength = self._fileHandle.seekToEndOfFile()
    }
    else
    {

        return nil  //The error is on this line
    }
}

如何解决此问题，以免出现此错误:

How do fix this so I don't get this error:

类实例的所有存储属性必须在初始化之前 从初始化程序返回nil

All stored properties of a class instance must be initialized before returning nil from an initializer

推荐答案

您可以使其与变量和对super.init()的调用一起使用(用于在访问其属性之前创建self):

You can make it work with variables and a call to super.init() (for creating self before accessing its properties):

class Test: NSObject {
    var filePath: NSString!
    var _fileHandle: NSFileHandle!
    var _totalFileLength: CUnsignedLongLong!

    init?(filePath: String) {
        super.init()
        if let fileHandle = NSFileHandle(forReadingAtPath: filePath)
        {
            self.filePath = filePath
            self._fileHandle = NSFileHandle(forReadingAtPath: filePath)
            self._totalFileLength = self._fileHandle.seekToEndOfFile()
        }
        else
        {
            return nil
        }
    }
}

但是，如果您打算坚持使用常量版本，那么它超出了我的舒适范围，也许

But if you plan to stick to your version with constants, then it's out of my comfort zone, and maybe this answer could be of help.

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