ios - 将字符串的一部分复制到另一个字符串

Question

我必须解析这些类型的字符串:

let result1 = "t=20171017T1201&s=349.00&fn=8712000100030779&i=21456&fp=124519970&n=1"
let result2 = "t=20171016T180757&s=92.00&fn=8710000101140572&i=17711&fp=4191934636&n=1"

我需要以某种方式提取 t 和 fn 参数并将它们保存到另一个字符串:

print(t1)    // 20171017T1201
print(fn1)   // 8712000100030779
print(t2)    // 20171016T180757
print(fn2)   // 8710000101140572

我设法通过逐个符号检查整个字符串来获取这些参数，但一定有更好的方法来做到这一点。

Answer 1

您需要使用 components(separatedBy: _) 将字符串拆分为可解析的对。

let result1 = "t=20171017T1201&s=349.00&fn=8712000100030779&i=21456&fp=124519970&n=1"
let result2 = "t=20171016T180757&s=92.00&fn=8710000101140572&i=17711&fp=4191934636&n=1"

func value(for name: String, in query: String) -> String? {
    for params in query.components(separatedBy: "&") {
        let pair = params.components(separatedBy: "=")
        if (pair.first == name) { 
            return pair.last
        }
    }
    return nil
}

print(value(for: "t", in: result1))
print(value(for: "fn", in: result1))
print(value(for: "t", in: result2))
print(value(for: "fn", in: result2))