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归档、解档

归档、解档

作者: myk | 来源:发表于2021-11-08 17:42 被阅读0次

    我对归档和解档的理解是

    归档就是把要保存的内容转成Data之后写入指定的路径中。
    解档就是把指定路径下的Data转成我们需要的数据类型。

    对象的归档、解档

    iOS 12.0以后一个安全归档协议NSSecureCoding继承自NSCoding,多了一个static var supportsSecureCoding: Bool属性。

    Student类,继承自`NSObject`,遵循`NSSecureCoding`协议。
    class Student: NSObject, NSSecureCoding {
        var name: String?
        var age: Int? = 1
        var height: CGFloat = 0.5
        var weight: CGFloat = 5.0
        
        init(name: String? = nil, age: Int? = nil, height: CGFloat = 1.80, weight: CGFloat = 75) {
            self.name = name
            self.age = age
            self.height = height
            self.weight = weight
            super.init()
        }
        
        /// NSSecureCoding
        static var supportsSecureCoding: Bool = true
        func encode(with coder: NSCoder) {
            coder.encode(name, forKey: "name")
            coder.encode(age, forKey: "age")
            coder.encode(height, forKey: "height")
            coder.encode(weight, forKey: "weight")
        }
        required init?(coder: NSCoder) {
            name = coder.decodeObject(forKey: "name") as? String
            age = coder.decodeObject(forKey: "age") as? Int
            height = coder.decodeObject(forKey: "height") as! CGFloat
            weight = coder.decodeObject(forKey: "weight") as! CGFloat
            super.init()
        }
        override var description: String {
            return "name: \(self.name), age: \(self.age), height: \(self.height), weight: \(self.weight)"
        }
    }
    

    Student归档和解档

    /// 要归档对象
    let stu = Student()
    /// 归档路径 <路径必须是通过`fileURLWithPath`这个函数创建的>
    let pathStu = (NSTemporaryDirectory() as NSString).appendingPathComponent("student.plist")
    let urlStu = URL(fileURLWithPath: pathStu)
    if #available(iOS 11.0, *) {
        do {
            /// 归档对象转 Data
            let data = try NSKeyedArchiver.archivedData(withRootObject: stu, requiringSecureCoding: true)
            ///  写进置顶路径
            try data.write(to: urlStu)
        } catch {
            print("stu 失败 \(error)")
        }
    } else {
        let success = NSKeyedArchiver.archiveRootObject(stu, toFile: pathStu)
        print("succ == \(success)")
    }
    
    /// 解档
    do {
        /// 获取路径下的Data
        let dataStu = try Data(contentsOf: urlStu)
        var stu: Student
        /// 把Data 转成 对象
        if #available(iOS 11.0, *) {
            stu = try NSKeyedUnarchiver.unarchivedObject(ofClass: Student.self, from: dataStu)!
        } else {
            stu = NSKeyedUnarchiver.unarchiveObject(with: dataStu) as! Student
        }
        print("\(stu.name), \(stu.score),\(stu.height)")
    } catch {
        
    }
    

    数组、字典、字符串等的归档<本地存储>

    func archiveSmapleDemo(){
        let arr = ["123","111"]
        /// 获取本地存储的路径
        let pathArr = (NSTemporaryDirectory() as NSString).appendingPathComponent("arr.txt")
        let urlArr = URL(fileURLWithPath: pathArr)
        do {
            /// 转成Data 并且写入数据
            let data = try JSONSerialization.data(withJSONObject: arr, options: .prettyPrinted)
            try data.write(to: urlArr)
        } catch {
            
        }
        
        do {
            /// 根据路径取出Data
            let dataArr = try Data(contentsOf: urlArr)
            /// 解析成数组
            let arr = try JSONSerialization.jsonObject(with: dataArr, options: .mutableContainers) as! [String]
            print(arr)
        } catch {
            
        }
    }
    

    自定义对象数组归档、解档

    func archiveSmapleDemo(){
        let s1 = Student()
        let s2 = Student()
        let s3 = Student()
        
        let arr = [s1,s2,s3]
        let pathArr = (NSTemporaryDirectory() as NSString).appendingPathComponent("arr.data")
        let urlArr = URL(fileURLWithPath: pathArr)
        /// 归档
        do {
            let data: Data
            /// 转成Data 并且写入本地
            /// 自定义对象要用 `NSKeyedArchiver`转成Data
            if #available(iOS 11.0, *) {
                data = try NSKeyedArchiver.archivedData(withRootObject: arr, requiringSecureCoding: true)
            } else {
                data = NSKeyedArchiver.archivedData(withRootObject: arr)
            }
            try data.write(to: urlArr)
        } catch {
            print("error == \(error)")
        }
        /// 解档
        do {
            /// 根据路径取出Data
            let dataArr = try Data(contentsOf: urlArr)
            if #available(iOS 14.0, *) {
                /// 直接解档成 对象数组
                if let arr = try NSKeyedUnarchiver.unarchivedArrayOfObjects(ofClass: Student.self, from: dataArr) {
                    arr.forEach { p in
                        print("p.desc == \(p.description)")
                    }
                }else {
                    
                }
            } else {
                /// 解档之后转换成对象数组
                if let arr = NSKeyedUnarchiver.unarchiveObject(with: dataArr) as? [Student]{
                    arr.forEach { p in
                        print("p.desc == \(p.description)")
                    }
                }
            }
        } catch {
            
        }
    }
    

    学习资料:
    iOS数组里为自定义对象情况下的归档

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