arrays - 如何更好地使用repeat while循环进行索引和数组

Question

我想从给定数组中随机选择一个 KanjiCard 结构体项目，将属性“kanji”添加到另一个临时数组中并执行检查，如果随机选择的 struct.kanji 存在于 yetShowedArray 中> 重复随机选择，直到找到 yetShowedArray 中不存在汉字的结构才能使用它

实际的重复/同时流程并不能保证它会发生。

//test for the not repeating run *************************************************************************************

        //check if the two array have the same number of items
        guard arrayToUse.count !=  yetShowedArray.count else {
            print("finished all the kanji")
            var matching = 0
            for element in arrayToUse {
                if yetShowedArray.contains(element.kanji!){
                    matching += 1
                }
            }
            print("matching kanji are : \(matching)")
            return
        }

        var random = Int(arc4random_uniform(UInt32(arrayToUse.count)))

        //Instance
        kanjiToShow = arrayToUse[random]
        guard let kanjiToTrack = kanjiToShow.kanji else {
            print("kanjiToTrack is nil!!!")
            return
        }


        if yetShowedArray.contains(kanjiToTrack){
            print("contained")

            repeat {
                random = Int(arc4random_uniform(UInt32(arrayToUse.count)))
                kanjiToShow = arrayToUse[random]

            } while yetShowedArray.contains(kanjiToTrack)
            print("refreshed random")

        }
        else {
            print("never used before")
        }

        yetShowedArray.append(kanjiToTrack)
        print(yetShowedArray)

        print("arrayToUse: \(arrayToUse.count) yetShowedArray: \(yetShowedArray.count)")

        //test for the not repeating run *************************************************************************************

解决方案

在 Anton Novoselov 的回答后找到

我将 let kanjiToTrack 更改为 var，然后在重复循环内刷新它

//Instance
        kanjiToShow = arrayToUse[random]
        guard var kanjiToTrack = kanjiToShow.kanji else {
            print("kanjiToTrack is nil!!!")
            return
        }


        if yetShowedArray.contains(kanjiToTrack){
            print("contained")

            repeat {
                random = Int(arc4random_uniform(UInt32(arrayToUse.count)))
                kanjiToShow = arrayToUse[random]
                kanjiToTrack = kanjiToShow.kanji!


            } while yetShowedArray.contains(kanjiToTrack)

            print("refreshed random")

        }
        else {
            print("never used before")
        }

第二种解决方案

let random = Int(arc4random_uniform(UInt32(arrayToUse.count)))

    //Instance
    kanjiToShow = arrayToUse[random]
    guard kanjiToShow.kanji != nil else {
        print("kanjiToTrack is nil!!!")
        return
    }

    arrayToUse.remove(at: random)

Answer 1

尝试在重复循环内再次刷新 kanjiToTrack。正如您所说，它是结构-值类型，因此您似乎在 while 子句中检查相同的 kanjiToTrack 。试试这个:

       repeat {
            random = Int(arc4random_uniform(UInt32(arrayToUse.count)))
            kanjiToShow = arrayToUse[random]
            guard let kanjiToTrack = kanjiToShow.kanji else {return}


        } while yetShowedArray.contains(kanjiToTrack)