我无法正确解码我的Codable类型.我已经阅读了一些关于使用相关类型制作Codable枚举的教程.我搜索过拼写错误,名称不匹配,或其他什么,但我无法发现任何错误.然而,每当我尝试对这些结构进行解码时(一个图层…这在扩展中的一个图层上定义了一个“属性”……但是图层的所有其他预定义部分都被正确地加/解码),我点击了解码(来自解码器:)方法中的“未找到密钥”异常.
extension Layer {
struct Attribute: Codable {
enum Value: Codable {
case pulse(Double)
case flash(Double)
case draw(Double)
private enum CodingKeys: String,CodingKey {
case pulse,flash,draw
}
func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
switch self {
case .pulse(let value):
try container.encode(value,forKey: .pulse)
case .flash(let value):
try container.encode(value,forKey: .flash)
case .draw(let value):
try container.encode(value,forKey: .draw)
}
}
init(from decoder: Decoder) throws {
let values = try decoder.container(keyedBy: CodingKeys.self)
do {
let value = try values.decode(Double.self,forKey: .pulse)
self = .pulse(value)
} catch (let error) {
print(error)
}
do {
let value = try values.decode(Double.self,forKey: .draw)
self = .draw(value)
} catch (let error) {
print(error)
}
do {
let value = try values.decode(Double.self,forKey: .flash)
self = .flash(value)
} catch (let error) {
print(error)
}
self = .draw(0.0)
}
}
var value: Value
init(value: Value) {
self.value = value
}
}
}
我认为在解码之前,你应首先检查解码器容器中是否存在密钥.目前,你这样做：
do {
let value = try values.decode(Double.self,forKey: .pulse)
self = .pulse(value)
} catch (let error) {
print(error)
}
do {
let value = try values.decode(Double.self,forKey: .draw)
self = .draw(value)
} catch (let error) {
print(error)
}
do {
let value = try values.decode(Double.self,forKey: .flash)
self = .flash(value)
} catch (let error) {
print(error)
}
解码器容器无法在那里拥有所有三个键,不是吗？
所以,解码前检查：
if values.contains(.pulse) {
do {
let value = try values.decode(Double.self,forKey: .pulse)
self = .pulse(value)
return // remember to return here,so you don't set self back to .draw(0.0) again!
} catch (let error) {
print(error)
}
} else if values.contains(.draw) {
do {
let value = try values.decode(Double.self,forKey: .draw)
self = .draw(value)
return
} catch (let error) {
print(error)
}
} else if values.contains(.flash) {
do {
let value = try values.decode(Double.self,forKey: .flash)
self = .flash(value)
return
} catch (let error) {
print(error)
}
}
