将自定义对象存储在NSUserDefault中

Question

在我的应用程序中，我执行一些异步调用，这些调用会返回一些json。我解析这些响应并填充一些结构，如下所示：

public struct StudentInfo {
let availableExams : Int?
let course : String?
let courseLength : Int?
let department : String?
let enrolledExams : Int?
let name : String?
let surname : String?
let registrationDate : String?
let studentClass : String?
let studentId : String?
init?(json: JSON) {
    self.availableExams = "availableExams" <~~ json
    self.course = "course" <~~ json
    self.courseLength = "courseLength" <~~ json
    self.department = "department" <~~ json
    self.enrolledExams = "enrolledExams" <~~ json
    let auxName: String? = "name" <~~ json
    self.name = auxName?.firstCharacterUpperCase()
    let auxSurname: String? = "surname" <~~ json
    self.surname = auxSurname?.firstCharacterUpperCase()
    self.surname?.firstCharacterUpperCase()
    self.registrationDate = "registrationDate" <~~ json
    self.studentClass = "studentClass" <~~ json
    self.studentId = "studentID" <~~ json
}
}

我想使用NSUserDefault来存储这些对象，以便在没有可用的互联网连接来执行对外部web服务的API调用的情况下检索它们。这是一个可行的选择，还是有更简单的方法？

Answer 1

您可以使用这些函数来执行您想要的操作。。。

+ (id)getUserDefaultsForKey:(NSString *)key{
    return [NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:key]];
}

+ (void)setUserDefaults:(id)value forKey:(NSString *)key{
    [[NSUserDefaults standardUserDefaults] setObject:[NSKeyedArchiver archivedDataWithRootObject:value] forKey:key];
    [[NSUserDefaults standardUserDefaults] synchronize];
}
+ (void)deleteUserDefaultsForKey:(NSString *)key{
    [[NSUserDefaults standardUserDefaults] removeObjectForKey:key];
    [[NSUserDefaults standardUserDefaults] synchronize];
}

再试一次。。。但是您的自定义对象应该遵循下面的函数。

- (void)encodeWithCoder:(NSCoder *)coder
{
    [super encodeWithCoder:coder];
    [coder encodeObject:self.property forKey:@"property"];
}
- (instancetype)initWithCoder:(NSCoder *)coder {
    if (self = [super initWithCoder:coder]) {
        self.property = [coder decodeObjectForKey:@"property"];
    }
    return self;
}

在自定义对象中使用这两个函数，然后在用户默认值中使用以上函数保存该对象。

Answer 2

要在磁盘上保存自定义对象，必须确认该对象符合NSCoding。但是结构不能向NSCoding进行确认。我们可以在StudentInfo结构中添加一个符合NSCoding:的类

struct StudentInfo {
let course: String
static func encode(student: StudentInfo) {
let studentClassObject = HelperClass(student: student)
NSKeyedArchiver.archiveRootObject(studentClassObject, toFile: HelperClass.path())
}
static func decode() -> StudentInfo? {
let personClassObject = NSKeyedUnarchiver.unarchiveObjectWithFile(HelperClass.path()) as? HelperClass
return personClassObject?.student
}
}

extension StudentInfo {
class HelperClass: NSObject, NSCoding {
var student: StudentInfo?
init(student: StudentInfo) {
  self. student = student
  super.init()
}
class func path() -> String {
  let documentsPath = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true).first
  let path = documentsPath?.stringByAppendingString("/StudentInfo")
  return path!
}
  guard let course = aDecoder.decodeObjectForKey("course") as? String else    {     student = nil; 
 super.init(); 
 return nil 
 }
  student = StudentInfo(course: course)
  super.init()
}
func encodeWithCoder(aCoder: NSCoder) {
  aCoder.encodeObject(student!.course, forKey: "course")
    }
  }
}

let me = StudentInfo(course: "Swift",)
StudentInfo.encode(me)
let myClone = StudentInfo.decode()
firstNameLabel.text = myClone?.course

Answer 3

您可以解析数据并将其存储在核心数据中，而不是NSUserDefaults中，以实现高效的内存管理。您可以从数据库（核心数据）中取回数据，而不会出现任何互联网连接问题。将数据存储为数据库中的超越数据。