Question

我使用地图功能，必须将空字符串映射为nil，否则为字符串。问题是输入是否为？

var arr : Any? = ["hallo", "", nil, "hihi"]
let res = arr.map{ (($0 ?? "") as! String).isEmpty ? nil : $0 }
print(res)

你知道怎么做吗？

地图功能就在这里：

id <- (map["id"], TransformOf<Int, String>(fromJSON: { Int($0!) }, toJSON: { $0.map { String($0) } }))

https://github.com/Hearst-DD/ObjectMapper#custom-transforms

Answer 1

你的意思是这样的：

var arr : Any? = ["hallo", "", nil, "hihi"]
if let array = arr as? [String?] {
    let result = array.map { ($0?.isEmpty ?? true) ? nil : $0 }
    print(result)
}

Answer 2

存储数组Any?是有问题的，但如果你必须......

let arr: Any? = ["hallo", "", nil, "hihi"]

guard let casted = arr as? [String?] else {
    // handle error
    fatalError("arr is not a [String?]")
}

let result: [String?] = casted.map{
    guard let s = $0 else { return nil }
    return s.isEmpty ? nil : s
}

print(result as Any)

Swift将空字符串映射为nil

2 个答案: