ios - swift 1.2 "Cannot express tuple conversion"错误

Question

这个方法在 Swift 的最后一个稳定版本中运行良好，但在 Swift 1.2 中无法编译:

  final func rotateBlocks(orientation: Orientation) {
    if let blockRowColumnTranslation:Array<(columnDiff: Int, rowDiff: Int)> = blockRowColumnPositions[orientation] {
        for (idx, (columnDiff:Int, rowDiff:Int)) in enumerate(blockRowColumnTranslation) {
            blocks[idx].column = column + columnDiff
            blocks[idx].row = row + rowDiff
        }
    }
}

这一行:

for (idx, (columnDiff:Int, rowDiff:Int)) in enumerate(blockRowColumnTranslation) {

抛出以下错误:

"Cannot express tuple conversion "(index:Int, element:(columnDiff:Int,rowDiff:Int)) to "(Int, (Int, Int))"

关于这里发生的事情以及如何解决它有什么想法吗？

Answer 1

我会使用 typealias 来简化，但下面的编译对我来说没有错误。

var row: Int = 0
var column: Int = 1
struct block {
    var column: Int
    var row: Int
}
var blocks = [block]()

enum Orientation { case Up; case Down; }
typealias Diff = (columnDiff: Int, rowDiff: Int)
typealias DiffArray = Array<Diff>
typealias DiffArrayDict = [Orientation: DiffArray]

var blockRowColumnPositions = DiffArrayDict();

func rotateBlocks(orientation: Orientation) {
    if let blockRowColumnTranslation: DiffArray = blockRowColumnPositions[orientation] {
        for (idx, diff) in enumerate(blockRowColumnTranslation) {
            blocks[idx].column = column + diff.columnDiff
            blocks[idx].row = row + diff.rowDiff
        }
    }
}