请有人解释一下,为什么A部分的代码能正常运行,而B部分不能?让我很困惑。
可运行代码
struct Coded : Codable, Hashable {
public let avar1: String
public let avar2: String
enum CodingKeys: String, CodingKey {
case avar1 = "avar1"
case avar2 = "avar2"
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
print (container.allKeys)
avar1 = try container.decode(String.self, forKey: .avar1)
avar2 = try container.decode(String.self, forKey: .avar2)
}
}
let JSONStr = """
{
"avar1": "This is a string",
"avar2": "This is a string2",
}
"""
if let jsdata = JSONStr.data(using: .utf8) {
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
let aobj: Coded? = try? decoder.decode(Coded.self, from: jsdata)
print (aobj ?? "No object")
}
输出
[CodingKeys(stringValue: "avar1", intValue: nil), CodingKeys(stringValue: "avar2", intValue: nil)]
Coded(avar1: "This is a string", avar2: "This is a string2")
无法工作
struct Coded : Codable, Hashable {
public let avar1: String
public let avar2: String
enum CodingKeys: String, CodingKey {
case avar1 = "avar1"
case avar2 = "avar_2"
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
print (container.allKeys)
avar1 = try container.decode(String.self, forKey: .avar1)
avar2 = try container.decode(String.self, forKey: .avar2)
}
}
let JSONStr = """
{
"avar1": "This is a string",
"avar_2": "This is a string2",
}
"""
if let jsdata = JSONStr.data(using: .utf8) {
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
let aobj: Coded? = try? decoder.decode(Coded.self, from: jsdata)
print (aobj ?? "No object")
}
输出
[CodingKeys(stringValue: "avar1", intValue: nil)]
No object
第二个函数只会显示编码键,不带下划线。 但是,一旦我去掉下划线,它就会在所有键中具有编码键...
Swift 4.2 - Xcode 10.2.
有什么想法吗?