快速序列协议的Swift 2到3迁移

概述我正在尝试将以下代码从此库( https://github.com/dankogai/swift-json)转换为Swift 3兼容代码. 我很难弄清楚如何将Swift 2中使用的Sequence协议转换为Swift 3的正确版本.我找不到任何关于Swift 2 Sequence协议变化的文档与3相比. 这是我目前已尽可能转换为Swift 3的代码 extension JSON : Sequenc 我正在尝试将以下代码从此库( https://github.com/dankogai/swift-json)转换为Swift 3兼容代码.

我很难弄清楚如何将Swift 2中使用的Sequence协议转换为Swift 3的正确版本.我找不到任何关于Swift 2 Sequence协议变化的文档与3相比.

这是我目前已尽可能转换为Swift 3的代码

extension JsON : Sequence {    public func generate()->AnyIterator<(AnyObject,JsON)> {        switch _value {        case let o as NSArray:            var i = -1            return AnyIterator {                i=i+1                if i == o.count { return nil }                return (i as AnyObject,JsON(o[i]))            }        case let o as NSDictionary:            var ks = Array(o.allKeys.reversed())            return AnyIterator {                if ks.isEmpty { return nil }                if let k = ks.removeLast() as? String {                    return (k as AnyObject,JsON(o.value(forKey: k)!))                } else {                    return nil                }            }        default:            return AnyIterator{ nil }        }    }    public func mutablecopyOfTheObject() -> AnyObject {        return _value.mutablecopy as AnyObject    }}

我在具体细节中得到的错误在附图中.

如果你想玩它,整个代码对于JsON库来说相当短.它在下面：

////  Json.swift//  Json////  Created by Dan Kogai on 7/15/14.//  copyright (c) 2014 Dan Kogai. All rights reserved.//import Foundation/// initpublic class JsON {    public let _value:AnyObject    /// unwraps the JsON object    public class func unwrap(obj:AnyObject) -> AnyObject {        switch obj {        case let Json as JsON:            return Json._value        case let ary as NSArray:            var ret = [AnyObject]()            for v in ary {                ret.append(unwrap(obj: v as AnyObject))            }            return ret as AnyObject        case let dict as NSDictionary:            var ret = [String:AnyObject]()            for (ko,v) in dict {                if let k = ko as? String {                    ret[k] = unwrap(obj: v as AnyObject)                }            }            return ret as AnyObject        default:            return obj        }    }    /// pass the object that was returned from    /// NSJsONSerialization    public init(_ obj:Any) { self._value = JsON.unwrap(obj: obj as AnyObject) }    /// pass the JsON object for another instance    public init(_ Json:JsON){ self._value = Json._value }}/// class propertIEsextension JsON {    public typealias NSNull = Foundation.NSNull    public typealias NSError = Foundation.NSError    public class var null:NSNull { return NSNull() }    /// constructs JsON object from data    public convenIEnce init(data:NSData) {        var err:NSError?        var obj:Any?        do {            obj = try JsONSerialization.JsonObject(                with: data as Data,options:[])        } catch let error as NSError {            err = error            obj = nil        }        self.init(err != nil ? err! : obj!)    }    /// constructs JsON object from string    public convenIEnce init(string:String) {        let enc:String.EnCoding = String.EnCoding.utf8        self.init(data: string.data(using: enc)! as NSData)    }    /// parses string to the JsON object    /// same as JsON(string:String)    public class func parse(string:String)->JsON {        return JsON(string:string)    }    /// constructs JsON object from the content of NSURL    public convenIEnce init(nsurl:NSURL) {        var enc:String.EnCoding = String.EnCoding.utf8        do {            let str = try Nsstring(contentsOf:nsurl as URL,usedEnCoding:&enc.rawValue)            self.init(string:str as String)        } catch let err as NSError {            self.init(err)        }    }    /// fetch the JsON string from NSURL and parse it    /// same as JsON(nsurl:NSURL)    public class func fromNSURL(nsurl:NSURL) -> JsON {        return JsON(nsurl:nsurl)    }    /// constructs JsON object from the content of URL    public convenIEnce init(url:String) {        if let nsurl = NSURL(string:url) as NSURL? {            self.init(nsurl:nsurl)        } else {            self.init(NSError(                domain:"JsONErrorDomain",code:400,userInfo:[NSLocalizedDescriptionKey: "malformed URL"]                )            )        }    }    /// fetch the JsON string from URL in the string    public class func fromURL(url:String) -> JsON {        return JsON(url:url)    }    /// does what JsON.stringify in ES5 does.    /// when the 2nd argument is set to true it pretty prints    public class func stringify(obj:AnyObject,pretty:Bool=false) -> String! {        if !JsONSerialization.isValIDJsONObject(obj) {            let error = JsON(NSError(                domain:"JsONErrorDomain",code:422,userInfo:[NSLocalizedDescriptionKey: "not an JsON object"]                ))            return JsON(error).toString(pretty: pretty)        }        return JsON(obj).toString(pretty: pretty)    }}/// instance propertIEsextension JsON {    /// access the element like array    public subscript(IDx:Int) -> JsON {        switch _value {        case _ as NSError:            return self        case let ary as NSArray:            if 0 <= IDx && IDx < ary.count {                return JsON(ary[IDx])            }            return JsON(NSError(                domain:"JsONErrorDomain",code:@R_301_6939@,userInfo:[                    NSLocalizedDescriptionKey:                    "[\(IDx)] is out of range"                ]))        default:            return JsON(NSError(                domain:"JsONErrorDomain",code:500,userInfo:[                    NSLocalizedDescriptionKey: "not an array"                ]))        }    }    /// access the element like dictionary    public subscript(key:String)->JsON {        switch _value {        case _ as NSError:            return self        case let dic as NSDictionary:            if let val:Any = dic[key] { return JsON(val) }            return JsON(NSError(                domain:"JsONErrorDomain",userInfo:[                    NSLocalizedDescriptionKey:                    "[\"\(key)\"] not found"                ]))        default:            return JsON(NSError(                domain:"JsONErrorDomain",userInfo:[                    NSLocalizedDescriptionKey: "not an object"                ]))        }    }    /// access Json data object    public var data:AnyObject? {        return self.isError ? nil : self._value    }    /// Gives the type name as string.    /// e.g.  if it returns "Double"    ///       .asDouble returns Double    public var type:String {        switch _value {        case is NSError:        return "NSError"        case is NSNull:         return "NSNull"        case let o as NSNumber:            switch String(cString:o.objCType) {            case "c","C":              return "Bool"            case "q","l","i","s":    return "Int"            case "Q","L","I","S":    return "UInt"            default:                    return "Double"            }        case is Nsstring:               return "String"        case is NSArray:                return "Array"        case is NSDictionary:           return "Dictionary"        default:                        return "NSError"        }    }    /// check if self is NSError    public var isError:      Bool { return _value is NSError }    /// check if self is NSNull    public var isNull:       Bool { return _value is NSNull }    /// check if self is Bool    public var isBool:       Bool { return type == "Bool" }    /// check if self is Int    public var isInt:        Bool { return type == "Int" }    /// check if self is UInt    public var isUInt:       Bool { return type == "UInt" }    /// check if self is Double    public var isDouble:     Bool { return type == "Double" }    /// check if self is any type of number    public var isNumber:     Bool {        if let o = _value as? NSNumber {            let t = String(cString:o.objCType)            return  t != "c" && t != "C"        }        return false    }    /// check if self is String    public var isstring:     Bool { return _value is Nsstring }    /// check if self is Array    public var isArray:      Bool { return _value is NSArray }    /// check if self is Dictionary    public var isDictionary: Bool { return _value is NSDictionary }    /// check if self is a valID leaf node.    public var isLeaf:       Bool {        return !(isArray || isDictionary || isError)    }    /// gives NSError if it holds the error. nil otherwise    public var asError:NSError? {        return _value as? NSError    }    /// gives NSNull if self holds it. nil otherwise    public var asNull:NSNull? {        return _value is NSNull ? JsON.null : nil    }    /// gives Bool if self holds it. nil otherwise    public var asBool:Bool? {        switch _value {        case let o as NSNumber:            switch String(cString:o.objCType) {            case "c","C":  return Bool(o.boolValue)            default:                return nil            }        default: return nil        }    }    /// gives Int if self holds it. nil otherwise    public var asInt:Int? {        switch _value {        case let o as NSNumber:            switch String(cString:o.objCType) {            case "c","C":                return nil            default:                return Int(o.int64Value)            }        default: return nil        }    }    /// gives Int32 if self holds it. nil otherwise    public var asInt32:Int32? {        switch _value {        case let o as NSNumber:            switch String(cString:o.objCType) {            case "c","C":                return nil            default:                return Int32(o.int64Value)            }        default: return nil        }    }    /// gives Int64 if self holds it. nil otherwise    public var asInt64:Int64? {        switch _value {        case let o as NSNumber:            switch String(cString:o.objCType) {            case "c","C":                return nil            default:                return Int64(o.int64Value)            }        default: return nil        }    }    /// gives float if self holds it. nil otherwise    public var asfloat:float? {        switch _value {        case let o as NSNumber:            switch String(cString:o.objCType) {            case "c","C":                return nil            default:                return float(o.floatValue)            }        default: return nil        }    }    /// gives Double if self holds it. nil otherwise    public var asDouble:Double? {        switch _value {        case let o as NSNumber:            switch String(cString:o.objCType) {            case "c","C":                return nil            default:                return Double(o.doubleValue)            }        default: return nil        }    }    // an alias to asDouble    public var asNumber:Double? { return asDouble }    /// gives String if self holds it. nil otherwise    public var asstring:String? {        switch _value {        case let o as Nsstring:            return o as String        default: return nil        }    }    /// if self holds NSArray,gives a [JsON]    /// with elements therein. nil otherwise    public var asArray:[JsON]? {        switch _value {        case let o as NSArray:            var result = [JsON]()            for v:Any in o { result.append(JsON(v)) }            return result        default:            return nil        }    }    /// if self holds NSDictionary,gives a [String:JsON]    /// with elements therein. nil otherwise    public var asDictionary:[String:JsON]? {        switch _value {        case let o as NSDictionary:            var result = [String:JsON]()            for (ko,v): (Any,Any) in o {                if let k = ko as? String {                    result[k] = JsON(v)                }            }            return result        default: return nil        }    }    /// YIElds date from string    public var asDate:NSDate? {        if let dateString = _value as? String {            let dateFormatter = DateFormatter()            dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZ"            return dateFormatter.date(from: dateString) as NSDate?        }        return nil    }    /// gives the number of elements if an array or a dictionary.    /// you can use this to check if you can iterate.    public var count:Int {        switch _value {        case let o as NSArray:      return o.count        case let o as NSDictionary: return o.count        default: return 0        }    }    public var length:Int { return self.count }    // gives all values content in JsON object.    public var allValues:JsON{        if(self._value.allValues == nil) {            return JsON([])        }        return JsON(self._value.allValues)    }    // gives all keys content in JsON object.    public var allKeys:JsON{        if(self._value.allKeys == nil) {            return JsON([])        }        return JsON(self._value.allKeys)    }}extension JsON : Sequence {    public func generate()->AnyIterator<(AnyObject,JsON(o.value(forKey: k)!))                } else {                    return nil                }            }        default:            return AnyIterator{ nil }        }    }    public func mutablecopyOfTheObject() -> AnyObject {        return _value.mutablecopy as AnyObject    }}extension JsON : customstringconvertible {    /// stringifIEs self.    /// if pretty:true it pretty prints    public func toString(pretty:Bool=false)->String {        switch _value {        case is NSError: return "\(_value)"        case is NSNull: return "null"        case let o as NSNumber:            switch String(cString:o.objCType) {            case "c","C":                return o.boolValue.description            case "q","s":                return o.int64Value.description            case "Q","S":                return o.uint64Value.description            default:                switch o.doubleValue {                case 0.0/0.0:   return "0.0/0.0"    // NaN                case -1.0/0.0:  return "-1.0/0.0"   // -infinity                case +1.0/0.0:  return "+1.0/0.0"   //  infinity                default:                    return o.doubleValue.description                }            }        case let o as Nsstring:            return o.deBUGDescription        default:            let opts = pretty ? JsONSerialization.WritingOptions.prettyPrinted : JsONSerialization.WritingOptions()            if let data = (try? JsONSerialization.data(                withJsONObject: _value,options:opts)) as NSData? {                    if let result = Nsstring(                        data:data as Data,enCoding:String.EnCoding.utf8.rawValue                        ) as? String {                            return result                    }            }            return "YOU ARE NOT SUPPOSED TO SEE THIS!"        }    }    public var description:String { return toString() }}extension JsON : Equatable {}public func ==(lhs:JsON,rhs:JsON)->Bool {    // print("lhs:\(lhs),rhs:\(rhs)")    if lhs.isError || rhs.isError { return false }    else if lhs.isLeaf {        if lhs.isNull   { return lhs.asNull   == rhs.asNull }        if lhs.isBool   { return lhs.asBool   == rhs.asBool }        if lhs.isNumber { return lhs.asNumber == rhs.asNumber }        if lhs.isstring { return lhs.asstring == rhs.asstring }    }    else if lhs.isArray {        for i in 0..<lhs.count {            if lhs[i] != rhs[i] { return false }        }        return true    }    else if lhs.isDictionary {        for (k,v) in lhs.asDictionary! {            if v != rhs[k] { return false }        }        return true    }    fatalError("JsON == JsON Failed!")}

在Swift 3中,generate()已重命名为makeIterator().更改函数名称应该可以解决问题. (请注意,其他名称也已更改,例如AnyGenerator→AnyIterator,但看起来已经在您的代码中处理过了.)

此更改已作为SE-0006: Apply API Guidelines to the Standard Library的一部分实施.

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