Swift: 尝试实现 NSCoding

Question

我正在尝试将 NSCoding 协议添加到我的自定义 class:

class Convo: NSObject, NSCoding {
    var name: String
    var pic: UIImage

    override init() {
        self.name = "Dror"
        self.pic = UIImage (named: "NoPic.png")!
        super.init()
    }

    required init(coder aDecoder: NSCoder) {
        self.name = aDecoder.decodeObjectForKey("name") as! String
        self.pic = aDecoder.decodeObjectForKey("pic") as! UIImage
    }

    func encodeWithCoder(aCoder: NSCoder) {
        aCoder.encodeObject(self.name, forKey: "name")
        aCoder.encodeObject(self.pic, forKey: "pic")
    }

}

但它在以下行弹出错误：

self.pic = aDecoder.decodeObjectForKey("pic") as! UIImage

控制台中的错误是：

fatal error: unexpectedly found nil while unwrapping an Optional value

而xcode中的错误是：

Thread 1:EXC_BAD_INSTRUCTION(code=EXC_I386_INVOP,subcode=0x0)

我不知道该怎么办。

编辑：当运行这个代码：

class Convo: NSObject, NSCoding {
    var name: String
    var pic: UIImage!

    override init() {
        self.name = "Dror"
        self.pic = UIImage (named: "NoPic.png")!
        super.init()
    }

    required init(coder aDecoder: NSCoder) {
        self.name = aDecoder.decodeObjectForKey("name") as! String
        self.pic = aDecoder.decodeObjectForKey("pic") as? UIImage
    }

    func encodeWithCoder(aCoder: NSCoder) {
        aCoder.encodeObject(self.name, forKey: "name")
        aCoder.encodeObject(self.pic, forKey: "pic")
    }
}

它编译正常，但是 self.pic 最后是 nil 而不是 UIImage (named: "NoPic.png")

Answer 1

您确定您的资产中有所需的图像吗？ "NoPic.png"

好的，这里有一些变化：

class Convo: NSObject, NSCoding {
    var name: String
    var pic: UIImage?

    override init() {
        self.name = "Dror"
        self.pic = UIImage (named: "NoPic")
        super.init()
    }

它适用于我，但您必须确保图像存在于您的资产中。您可以跳过 .png 格式

Answer 2

这个有效：

class Convo: NSObject, NSCoding {
    var name: String
    var pic: UIImage?

    override init() {
        self.name = "Dror"
        self.pic = UIImage (named: "NoPic.png")
        super.init()
    }

    required init(coder aDecoder: NSCoder) {
        self.name = aDecoder.decodeObjectForKey("name") as! String
        self.pic = aDecoder.decodeObjectForKey("pic") as? UIImage
    }

    func encodeWithCoder(aCoder: NSCoder) {
        aCoder.encodeObject(self.name, forKey: "name")
        aCoder.encodeObject(self.pic, forKey: "pic")
    }
}

Swift: 尝试实现 NSCoding

Swift: Trying to implement NSCoding

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