鉴于此模型:
public class RSS2Feed {
public var channel: RSS2FeedChannel?
public init() {}
}
public class RSS2FeedChannel {
public var title: String?
public var description: String?
public init() {}
}
为了获取RSS2FeedChannel
实例的属性名称和值,我需要做什么?
这是我尝试的内容:
let feed = RSS2Feed()
feed.channel = RSS2FeedChannel()
feed.channel?.title = "The Channel Title"
let mirror = Mirror(reflecting: feed.channel)
mirror.children.first // ({Some "Some"}, {{Some "The Channel Title...
for (index, value) in mirror.children.enumerate() {
index // 0
value.label // "Some"
value.value // RSS2FeedChannel
}
最终,我尝试使用反射创建与实例匹配的Dictionary
,但到目前为止,我无法获取实例的属性名称和值。
文档说:
可以在适当时使用可选标签,例如表示存储属性或活动枚举大小写的名称,并在字符串传递给后代方法时用于查找。
然而我只得到一些"一些"字符串。
此外,value属性返回一个类型为RSS2FeedChannel
的字符串,当我希望每个孩子都是&#34;反映实例结构的元素时。&#34;!< / p>
答案 0 :(得分:4)
当我理解正确时,这应解决你的问题:
func aMethod() -> Void {
let feed = RSS2Feed()
feed.channel = RSS2FeedChannel()
feed.channel?.title = "The Channel Title"
// feed.channel?.description = "the description of your channel"
guard let channel = feed.channel else {
return
}
let mirror = Mirror(reflecting: channel)
for child in mirror.children {
guard let key = child.label else {
continue
}
let value = child.value
guard let result = self.unwrap(value) else {
continue
}
print("\(key): \(result)")
}
}
private func unwrap(subject: Any) -> Any? {
var value: Any?
let mirrored = Mirror(reflecting:subject)
if mirrored.displayStyle != .Optional {
value = subject
} else if let firstChild = mirrored.children.first {
value = firstChild.value
}
return value
}
swift 3的一些小变化:
private func unwrap(_ subject: Any) -> Any? {
var value: Any?
let mirrored = Mirror(reflecting:subject)
if mirrored.displayStyle != .optional {
value = subject
} else if let firstChild = mirrored.children.first {
value = firstChild.value
}
return value
}
答案 1 :(得分:1)
您可以使用Mirror对象上的descendent
方法获取此信息。如果未找到值或选项包含任何值,它将返回nil。
let mirror = Mirror(reflecting: feed.channel)
let child1 = mirror.descendant("Some", "title") // "The Channel Title"
// or on one line
let child3 = Mirror(reflecting: feed).descendant("channel", "Some", "title")