Question

因此，我不想使用用户默认设置，而是要使用Realm保留一些设置。

我为设置创建了一个类进口基金会导入RealmSwift

class NutritionSettings: Object {
    @objc dynamic var calories: Int = 0
    @objc dynamic var proteins: Int = 0
    @objc dynamic var carbohydrates: Int = 0
    @objc dynamic var fats: Int = 0
}

但是在我的视图控制器中，我不知道如何只保存一个实例我已经尝试过

let realm = try! Realm()
let settings = NutritionSettings()

    do {
    try realm.write{
        settings.calories = cals!
        settings.carbohydrates = carbs!
        settings.fats = fats!
        settings.proteins = proteins!
        }
    } catch {
        print("error saving settings")
    }

因为我知道执行realm.add只会添加另一个NutritionSettings对象，这不是我想要的。我无法使用文档澄清任何内容。任何帮助将不胜感激。

Answer 1

如果查看示例领域提供的https://realm.io/docs/swift/latest，您会看到，仅保存一个对象，您仍然需要添加。将对象添加到数据库后，您可以获取该对象并进行修改内部属性的写操作

let realm = try! Realm()
let settings = NutritionSettings()
settings.id = 1
do {
try realm.write{
     realm.add(settings)

    }
} catch {
    print("error saving settings")
}

接下来，您可以获取并修改您保存的单个实例

let realm = try! Realm()
let settings = realm.objects(NutritionSettings.self).filter("id == 1").first

do {
try realm.write{
    settings.calories = cals!
    settings.carbohydrates = carbs!
    settings.fats = fats!
    settings.proteins = proteins!
    }
} catch {
    print("error saving settings")
}

Answer 2

当我尝试保存用户会话对象时，我在项目中遇到了类似的问题。如果要保存唯一对象，请重写primaryKey（）类方法并为其设置唯一键。

@objcMembers class NutritionSettings: Object {

     static let uniqueKey: String = "NutritionSettings"

     dynamic var uniqueKey: String = NutritionSettings.uniqueKey
     dynamic var calories: Int = 0

     override class func primaryKey() -> String? {
          return "uniqueKey"
     }
}

然后使用唯一键接收对象。

// Saving

let settings = NutritionSettings()
settings.calories = 100

do {
    let realm = try Realm()
    try realm.write {
        realm.add(settings, update: .modified)
    }
} catch {
    // Error handling
}

// Reading

var settings: NutritionSettings?

do {
    let realm = try Realm()
    let key = NutritionSettings.uniqueKey
    settings = realm.object(ofType: NutritionSettings.self, forPrimaryKey: key)
} catch {
    // Error handling
}

if let settings = settings {
    // Do stuff
}

希望它会对别人有帮助。

如何在领域中仅保存一个类实例

2 个答案: