swift - 如何将 indexPath 数组拆分为单独的 indexPath 数组，每个数组的 indexPath 具有相同的 indexPath.section

Question

最近想根据indexPaths删除单元格，所以函数的入参是[IndexPath]类型，需要根据把[IndexPath]拆分成几个数组indexPath.section，有什么简单的方法吗？ 例如

indexPaths = 
[IndexPath(row: 0, section: 1),
 IndexPath(row: 1, section: 1), 
 IndexPath(row: 2, section: 1), 
 IndexPath(row: 2, section: 0)]

想把这个转换成

indexPath1 = 
[IndexPath(row: 0, section: 1),
 IndexPath(row: 1, section: 1), 
 IndexPath(row: 2, section: 1)]

indexPath0 = 
[IndexPath(row: 2, section: 0)]

// maybe get a [Array]
[indexPath0, indexPath1]

Answer 1

一个可能的解决方案是首先构建一个字典，其中键是节号，值是该节中 IndexPath 的数组。

let indexPaths = [
    IndexPath(row: 0, section: 1),
    IndexPath(row: 1, section: 1),
    IndexPath(row: 2, section: 1),
    IndexPath(row: 2, section: 0),
]

let pathDict = Dictionary(grouping: indexPaths) { (path) in
    return path.section
}

然后你可以将这个字典映射到路径数组的数组中。但首先按部分对这些数组进行排序。

let sectionPaths = pathDict.sorted { (arg0, arg1) -> Bool in
    return arg0.key < arg1.key // sort by section
}.map { $0.value } // get just the arrays of IndexPath

print(sectionPaths)

输出:

[[[0, 2]], [[1, 0], [1, 1], [1, 2]]]