Ios 扩展where子句中的ArrayType

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从Swift 2.2转换过来后，我在Swift 3.0中得到了这个错误。数组的元素也是数组。那么如何在Swift 3.0中定义它呢？

@NDoc Updated！！看看，根据您的需要修改代码应该很容易。@MartinR谢谢！正是我需要的。

extension Array where Element : Collection, Element.Index == Int, Element.IndexDistance == Int {
    func transpose() -> [[Element.Iterator.Element]] {
        typealias InnerElement = Element.Iterator.Element
        if self.isEmpty { return [] }
        let count = self[0].count
        var out = [[InnerElement]](repeating: [InnerElement](), count: count)
        for outer in self {
            for (index, inner) in outer.enumerated() {
                out[index].append(inner)
            }
        }
        return out
    }
}

extension Array where Element : Collection, Element.Index == Int, Element.IndexDistance == Int {
    func transpose() -> [[Element.Iterator.Element]] {
        typealias InnerElement = Element.Iterator.Element
        if self.isEmpty { return [] }
        let count = self[0].count
        var out = [[InnerElement]](repeating: [InnerElement](), count: count)
        for outer in self {
            for (index, inner) in outer.enumerated() {
                out[index].append(inner)
            }
        }
        return out
    }
}