ios - 用高阶函数重构给定的 for-in 循环

Question

给定以下代码:

let assetsFetchResult = PHAsset.fetchAssets(in: panoramasCollection, options: fetchOptions)
private var pAssets = [PHAsset]()
for i in 0..<assetsFetchResult.count {
    let asset = assetsFetchResult.object(at: i)
    pAssets.append(asset)
}

如何使用 map、filter 或 reduce 等高阶函数重构 for-in 循环？如您所见，我依赖于索引变量，各种高阶函数似乎没有在各自的闭包中给我索引。

Answer 1

map、filter 等“高阶函数”不适用于PHFetchResult，assetsFetchResult 是。

你可以这样做:

private var pAssets = [PHAsset]()
assetsFetchResult.enumerateObjects { (asset, index, stop) in
    pAssets.append(asset)
}