数组 – 如何让NSCoder对Swift结构数组进行编码解码？

概述我有一个必须符合NSCoding并且包含一组UInt64值的对象.如何使用NSCoder对其进行编码/解码？额外问题：如何最紧凑地编码？ (它必须进入保存的Game Center状态数据,其大小有限.) 理想情况下,我只想写一个Int,它是数组的大小n,然后写入n次64位的UInt64,并以类似方式读取它.我可以这样做吗？ coder.encodeObject(values,forKey：“v”) 我有一个必须符合NSCoding并且包含一组UInt64值的对象.如何使用NSCoder对其进行编码/解码？额外问题：如何最紧凑地编码？ (它必须进入保存的Game Center状态数据,其大小有限.)

理想情况下,我只想写一个Int,它是数组的大小n,然后写入n次64位的UInt64,并以类似方式读取它.我可以这样做吗？

coder.encodeObject(values,forKey：“v”)不起作用.

class MyObject: NSCoding {    private var values: [UInt64]    // …    // MARK: - NSCoding    required init(coder decoder: NSCoder) {        // ???    }    func encodeWithCoder(coder: NSCoder) {        // ???    }}

这是一个将UInt64数组编码为的可能解决方案
一个字节数组.它的灵感来自 How to serialize C array with NSCoding?的答案.

class MyObject: NSObject,NSCoding {    var values: [UInt64] = []    init(values : [UInt64]) {        self.values = values    }    // MARK: - NSCoding    required init(coder decoder: NSCoder) {        super.init()        var count = 0        // decodeBytesForKey() returns an UnsafePointer<UInt8>,pointing to immutable data.        let ptr = decoder.decodeBytesForKey("values",returnedLength: &count)        // If we convert it to a buffer pointer of the appropriate type and count ...        let buf = UnsafeBufferPointer<UInt64>(start: UnsafePointer(ptr),count: count/sizeof(UInt64))        // ... then the Array creation becomes easy.        values = Array(buf)    }    func encodeWithCoder(coder: NSCoder) {        // This encodes both the number of bytes and the data itself.        coder.encodeBytes(UnsafePointer(values),length: values.count * sizeof(UInt64),forKey: "values")    }}

测试：

let obj = MyObject(values: [1,2,3,UInt64.max])let data = NSKeyedArchiver.archivedDataWithRootObject(obj)let dec = NSKeyedUnarchiver.unarchiveObjectWithData(data) as! MyObjectprint(dec.values) // [1,18446744073709551615]

更新Swift 3(Xcode 8)：

class MyObject: NSObject,NSCoding {    var values: [UInt64] = []    init(values : [UInt64]) {        self.values = values    }    // MARK: - NSCoding    required init(coder decoder: NSCoder) {        super.init()        var count = 0        // decodeBytesForKey() returns an UnsafePointer<UInt8>?,pointing to immutable data.        if let ptr = decoder.decodeBytes(forKey: "values",returnedLength: &count) {            // If we convert it to a buffer pointer of the appropriate type and count ...            let numValues = count / MemoryLayout<UInt64>.strIDe            ptr.withMemoryRebound(to: UInt64.self,capacity: numValues) {                let buf = UnsafeBufferPointer<UInt64>(start: UnsafePointer(),count: numValues)                // ... then the Array creation becomes easy.                values = Array(buf)            }        }    }    public func encode(with coder: NSCoder) {        // This encodes both the number of bytes and the data itself.        let numBytes = values.count * MemoryLayout<UInt64>.strIDe        values.withUnsafeBufferPointer {            .baseAddress!.withMemoryRebound(to: UInt8.self,capacity: numBytes) {                coder.encodeBytes(,length: numBytes,forKey: "values")            }        }    }}let obj = MyObject(values: [1,UInt64.max])let data = NSKeyedArchiver.archivedData(withRootObject: obj)let dec = NSKeyedUnarchiver.unarchiveObject(with: data) as! MyObjectprint(dec.values) // [1,18446744073709551615]

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