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Defaults.swift
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Defaults.swift
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//
// Defaults.swift
//
// Copyright (c) 2017 - 2018 Nuno Manuel Dias
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//
import Foundation
public class DefaultsKey {}
/// Represents a `Key` with an associated generic value type conforming to the
/// `Codable` protocol.
///
/// static let someKey = Key<ValueType>("someKey")
public final class Key<ValueType: Codable>: DefaultsKey {
fileprivate let _key: String
public init(_ key: String) {
_key = key
}
}
/// Provides strongly typed values associated with the lifetime
/// of an application. Apropriate for user preferences.
/// - Warning
/// These should not be used to store sensitive information that could compromise
/// the application or the user's security and privacy.
public final class Defaults {
private var userDefaults: UserDefaults
/// Shared instance of `Defaults`, used for ad-hoc access to the user's
/// defaults database throughout the app.
public static let shared = Defaults()
/// An instance of `Defaults` with the specified `UserDefaults` instance.
///
/// - Parameter userDefaults: The UserDefaults.
public init(userDefaults: UserDefaults = UserDefaults.standard) {
self.userDefaults = userDefaults
}
/// Deletes the value associated with the specified key, if any.
///
/// - Parameter key: The key.
public func clear<ValueType>(_ key: Key<ValueType>) {
userDefaults.set(nil, forKey: key._key)
userDefaults.synchronize()
}
/// Checks if there is a value associated with the specified key.
///
/// - Parameter key: The key to look for.
/// - Returns: A boolean value indicating if a value exists for the specified key.
public func has<ValueType>(_ key: Key<ValueType>) -> Bool {
return userDefaults.value(forKey: key._key) != nil
}
/// Returns the value associated with the specified key.
///
/// - Parameter key: The key.
/// - Returns: A `ValueType` or nil if the key was not found.
public func get<ValueType>(for key: Key<ValueType>) -> ValueType? {
if isSwiftCodableType(ValueType.self) || isFoundationCodableType(ValueType.self) {
return userDefaults.value(forKey: key._key) as? ValueType
}
guard let data = userDefaults.data(forKey: key._key) else {
return nil
}
do {
let decoder = JSONDecoder()
let decoded = try decoder.decode(ValueType.self, from: data)
return decoded
} catch {
#if DEBUG
print(error)
#endif
}
return nil
}
/// Sets a value associated with the specified key.
///
/// - Parameters:
/// - some: The value to set.
/// - key: The associated `Key<ValueType>`.
public func set<ValueType>(_ value: ValueType, for key: Key<ValueType>) {
if isSwiftCodableType(ValueType.self) || isFoundationCodableType(ValueType.self) {
userDefaults.set(value, forKey: key._key)
return
}
do {
let encoder = JSONEncoder()
let encoded = try encoder.encode(value)
userDefaults.set(encoded, forKey: key._key)
userDefaults.synchronize()
} catch {
#if DEBUG
print(error)
#endif
}
}
/// Checks if the specified type is a Codable from the Swift standard library.
///
/// - Parameter type: The type.
/// - Returns: A boolean value.
private func isSwiftCodableType<ValueType>(_ type: ValueType.Type) -> Bool {
switch type {
case is String.Type, is Bool.Type, is Int.Type, is Float.Type, is Double.Type:
return true
default:
return false
}
}
/// Checks if the specified type is a Codable, from the Swift's core libraries
/// Foundation framework.
///
/// - Parameter type: The type.
/// - Returns: A boolean value.
private func isFoundationCodableType<ValueType>(_ type: ValueType.Type) -> Bool {
switch type {
case is Date.Type:
return true
default:
return false
}
}
}