arrays - Swift 3 - 使用数组中的值按字典值过滤和排序字典数组

Question

我正在尝试以优雅的方式实现以下行为:

Reorder users by the id in userIds and filter out all users whose id isn't in userIds

尝试以“swift 方式”做到这一点:

var users = [["id": 3, "stuff": 2, "test": 3], ["id": 2, "stuff": 2, "test": 3], ["id": 1, "stuff": 2, "test": 3]]
var userIds = [1, 2, 3]

userIds.map({ userId in users[users.index(where: { $0["id"] == userId })!] })

产生重新排序和过滤的预期结果。但是，当 userIds 包含不属于 users 中的 user 的 ID 时，代码会崩溃(例如 4 ) 多亏了强制解包。

我缺少什么才能让它正常工作而不会崩溃？

Answer 1

var users = [
    ["id": 3, "stuff": 2, "test": 3],
    ["id": 2, "stuff": 2, "test": 3],
    ["id": 1, "stuff": 2, "test": 3]
]
var userIds = [2, 1, 3]

let filteredUsers = userIds.flatMap { id in
    users.first { $0["id"] == id }
}
print(filteredUsers)