Swift UserDefaultsWrapper

总要说点什么

import HandyJSON

extension Bool: HandyJSON {  }
extension String: HandyJSON {  }
extension Int: HandyJSON {  }

enum UserDefaultsWrapperKey {
    case base(String)
    case handyJSON(String)
}

@propertyWrapper
struct UserDefaultsWrapper<T: HandyJSON> {
    let key: UserDefaultsWrapperKey
    let defaultValue: T
    init(key: UserDefaultsWrapperKey, defaultValue: T) {
        self.key = key
        self.defaultValue = defaultValue
    }
    
    var wrappedValue: T {
        get {
            switch key {
            case .base(let keyString):
                return UserDefaults.standard.value(forKey: keyString) as? T ?? defaultValue
            case .handyJSON(let keyString):
                if let string = UserDefaults.standard.value(forKey: keyString) as? String, let object = T.deserialize(from: string) {
                    return object
                }
                return defaultValue
            }
        }
        set {
            switch key {
            case .base(let keyString):
                UserDefaults.standard.set(newValue, forKey: keyString)
            case .handyJSON(let keyString):
                UserDefaults.standard.set(newValue.toJSONString() ?? "", forKey: keyString)
            }
        }
    }
}
​

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