struct Task: Codable {
var content: String
var deadline: Date
var color: UIColor
...
}
有警告说“类型'任务'不符合协议'可解码'”和“类型'任务'不符合协议'可编码'”。我搜索并发现这是因为UIColor不符合Codable。但我不知道如何解决这个问题。所以...
如何制作UIColor Codable?
如果您只关心4种颜色组件,这是一个使用包装器结构的简单解决方案
struct Color : Codable {
var red : CGFloat = 0.0, green: CGFloat = 0.0, blue: CGFloat = 0.0, alpha: CGFloat = 0.0
var uiColor : UIColor {
return UIColor(red: red, green: green, blue: blue, alpha: alpha)
}
init(uiColor : UIColor) {
uiColor.getRed(&red, green: &green, blue: &blue, alpha: &alpha)
}
}
在这种情况下,您必须编写一个自定义初始化程序,将4种颜色组件从Color
转换为UIColor
,反之亦然。
struct Task: Codable {
private enum CodingKeys: String, CodingKey { case content, deadline, color }
var content: String
var deadline: Date
var color : UIColor
init(content: String, deadline: Date, color : UIColor) {
self.content = content
self.deadline = deadline
self.color = color
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
content = try container.decode(String.self, forKey: .content)
deadline = try container.decode(Date.self, forKey: .deadline)
color = try container.decode(Color.self, forKey: .color).uiColor
}
public func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encode(content, forKey: .content)
try container.encode(deadline, forKey: .deadline)
try container.encode(Color(uiColor: color), forKey: .color)
}
}
现在你可以编码和解码UIColor
let task = Task(content: "Foo", deadline: Date(), color: .orange)
do {
let data = try JSONEncoder().encode(task)
print(String(data: data, encoding: .utf8)!)
let newTask = try JSONDecoder().decode(Task.self, from: data)
print(newTask)
} catch { print(error) }
我使用UIColor
子类
final class Color: UIColor, Decodable {
convenience init(from decoder: Decoder) throws {
let container = try decoder.singleValueContainer()
let hexString = try container.decode(String.self)
self.init(hex: hexString)
}
}
因此,不需要每个类或结构来实现Decodable
协议的功能。在我看来,这是最方便的方式,特别是当一个类或结构中可以有许多颜色参数时。如果有必要,您可以以相同的方式实现Encodable
。
我用一个允许自动符合可编码的自定义类解决了这个问题。这是有益的,因为它可以防止将自定义一致性写入可编码。它还使得使用UIColor和CGColor更容易
class Color:Codable{
private var _green:CGFloat
private var _blue:CGFloat
private var _red:CGFloat
private var alpha:CGFloat
init(color:UIColor) {
color.getRed(&_red, green: &_green, blue: &_blue, alpha: &alpha)
}
var color:UIColor{
get{
return UIColor(red: _red, green: _green, blue: _blue, alpha: alpha)
}
set{
newValue.getRed(&_red, green:&_green, blue: &_blue, alpha:&alpha)
}
}
var cgColor:CGColor{
get{
return color.cgColor
}
set{
UIColor(cgColor: newValue).getRed(&_red, green:&_green, blue: &_blue, alpha:&alpha)
}
}
}