无法使用类型为“(字符串?！)"的参数列表调用“追加" [英] Cannot invoke 'append' with an argument list of type '(String?!)'

问题描述

我正在尝试将 Parse 中的用户名添加到数组中以在 UITableView 中显示它们，但是当我将用户名附加到我的数组时出现错误.

I'm trying to add usernames from Parse in an array to display them in a UITableView, but get an error when I'm appending the usernames to my array.

我得到的错误是:无法使用类型为(字符串?！)"的参数列表调用追加"

The error I get is: Cannot invoke 'append' with an argument list of type '(String?!)'

我做错了什么?

var usernames = [""]

func updateUsers() {      
    var query = PFUser.query()
    query!.whereKey("username", notEqualTo: PFUser.currentUser()!.username!)
    var fetchedUsers = query!.findObjects()

    for fetchedUser in fetchedUsers! {
        self.usernames.append(fetchedUser.username)
    }
}

推荐答案

我解决了我的问题.我将数组声明为空数组，并使用以下代码解开可选项:

I solved my problem. I declare the array as an empty array and for unwrap the optional with the following code:

var usernames = [String]()

self.usernames.removeAll(keepCapacity: true)

    for fetchedUser in fetchedUsers! {
        if let username = fetchedUser.username as String! {
            self.usernames.append(username)
        }
    }

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