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

问题描述

我正在尝试从数组中的Parse添加用户名以在UITableView中显示它们，但是在将用户名附加到数组中时出现错误.

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:无法用'(String ?!)'类型的参数列表调用'append'

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

我在做什么错了?

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数组:

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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