Question

斯威夫特对我来说很新，所以我很感激你的帮助我有一个数组：

let bankDict  = [
    ["bank": "b1", "currency": "c1", "buyrate": 0.11, "sellrate": 1.222, "officialrate": 2.15],
    ["bank": "b1", "currency": "c2", "buyrate": 3.11, "sellrate": 4.222, "officialrate": 5.15],
    ["bank": "b1", "currency": "c3", "buyrate": 7.11, "sellrate": 8.222, "officialrate": 9.15]]

我正在尝试创建一个应该从我的数组bankDict返回 buyrate / sellrate / officialrate 的函数。

到目前为止，我只创建了一个测试逻辑的循环：

for dict in bankDict {
    let b = dict["bank"]!
    let c = dict["currency"]!

    if b == "b1" && c == "c2" {
        let br = dict["buyrate"]!
        let sr = dict["sellrate"]!
        let or = dict["officialrate"]!
        println("\(br) -> \(sr) -> \(or)")
    }
}

正如预期的那样，我会回复：3.11 -> 4.222 -> 5.15

当我尝试创建功能时：

func showRates (bnk: String, crnc: String) -> (br: Double, sr: Double, or: Double) {
    for dict in bankDict {
        let b = dict["bank"]!
        let c = dict["currency"]!

        if b == bnk && c == crnc {
            let br = dict["buyrate"]
            let sr = dict["sellrate"]
            let or = dict["officialrate"]
            println("\(br) -> \(sr) -> \(or)")
        }

        return (br, sr, or)
    }
}

我收到错误：use of unresolved identifier 'sr'

Answer 1

你认为如果b不等于bnk或c到crnc会发生什么？在这种情况下，你的功能需要返回什么？如果要返回nil值，则可以执行以下操作

func showRates (bnk: String, crnc: String) -> (br: Double?, sr: Double?, or: Double?) {

for dict in bankDict {
    var b = dict["bank"]!
    var c = dict["currency"]!

    if b == bnk && c == crnc {
         var br = dict["buyrate"] as? Double
         var sr = dict["sellrate"] as? Double
         var or = dict["officialrate"] as? Double
         println("\(br) -> \(sr) -> \(or)")
         return (br, sr, or)
        }
}
return (nil, nil, nil)
}

Answer 2

这是一个范围问题。在{em> if-statement 的范围内定义了br，sr和or：

if b == bnk && c == crnc {
    let br = dict["buyrate"]
    let sr = dict["sellrate"]
    let or = dict["officialrate"]
    println("\(br) -> \(sr) -> \(or)")
}

因此，它们只能在该代码块中使用如果你将return语句移动到if语句的一部分就可以了（通过一些其他调整）：

let bankDict  = [
    ["bank": "b1", "currency": "c1","buyrate": 0.11, "sellrate": 1.222, "officialrate": 2.15],
    ["bank": "b1", "currency": "c2","buyrate": 3.11, "sellrate": 4.222, "officialrate": 5.15],
    ["bank": "b1", "currency": "c3","buyrate": 7.11, "sellrate": 8.222, "officialrate": 9.15]]

func showRates(bank: String, currency: String) -> (buyrate: Double, sellrate: Double, officialrate: Double)? {
    for dict in bankDict {
        if dict["bank"] == bank && dict["currency"] == currency {
            if let buyrate = dict["buyrate"] as? Double,
               let sellrate = dict["sellrate"] as? Double,
               let officialrate = dict["officialrate"] as? Double {
                return (buyrate, sellrate, officialrate)
            }
        }
    }

    return nil
}

SwiftStub-Code（不是Swift 1.2版本）

将字典数组传递给函数的问题

2 个答案: