Ex.
输入:var array: [Int] = [1, 2, 3, 1, 3, 4, 2, 1]
输出:
[[1, 1, 1], [2, 2], [3,3], [4]]
具有Dictionary(grouping:by:)
的解决方案
let array = [1, 2, 3, 1, 3, 4, 2, 1]
let output = Dictionary(grouping: array, by: {$0})
.values
.sorted(by: { $0[0] < $1[0] })