如何总共使用10个字符并确保随机使用4个不同集合中的至少一个字符 [英] How to have 10 characters total and make sure at least one character from 4 different sets is used randomly

问题描述

我有一个文本字段和一个生成随机字符集的按钮。设置1 =小写，设置2 =大写，设置3 =数字，设置4 =符号

I have a text field and a button that generates a random set of characters. Set 1 = lowercase, set 2 = uppercase, set 3 = numbers, set 4 = symbols

我希望按钮生成的字符数不少于10个，并且最少

I want the the button to generate no more no less that 10 characters and minimum pull from each of the sets at least once.

到目前为止，我的想法是

My idea of how to do it so far is

let roomIDGenerated = uniqueRoomID.text

let roomIDCount = roomIDGenerated?.characters.count

let randomCharacterSet = arc4random() upp

   while roomIDCount < 10 {
        <#code#>
    }

但是我不知道该怎么做...我不知道t总是希望前4个字符始终是每个字符。.也许最后使用了一组必需的字符。

But I don't see how to do it...i don't always want the first 4 characters to always be one of each.. maybe one of the required sets is used last.

我有点卡住了，任何帮助将不胜感激

I'm kinda stuck in general, any help would be appreciated

推荐答案

马丁评论了我采用的相同方法。这是我的实现：

Martin commented with the same approach I was taking. Here is my implementation:

extension CollectionType {
    var random: Generator.Element {
        guard !isEmpty else { fatalError("array cannot be empty") }
        let array = Array(self)
        return array[Int(arc4random_uniform(UInt32(array.count)))]
    }
}

// from http://stackoverflow.com/a/24029847/1223781
extension MutableCollectionType where Index == Int {
    func shuffled() -> Self {
        var copy = self
        copy.shuffle()
        return copy
    }

    mutating func shuffle() {
        guard count >= 2 else { return }

        for i in 0..<count - 1 {
            let j = Int(arc4random_uniform(UInt32(count - i))) + i
            guard i != j else { continue }
            swap(&self[i], &self[j])
        }
    }
}

let sets = ["abc", "ABC", "123", "#$%"].map { Array($0.characters) }
let size = 10

var randoms = sets.map { $0.random }
while randoms.count < 10 {
    randoms.append(sets.random.random)
}
print(randoms.shuffled()) // ["b", "b", "3", "c", "#", "%", "A", "#", "1", "%"]

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