swift - 如何返回一个数组？

Question

我试图返回一个包含所有变量的数组。所以我可以将所有内容存储在一个数组中。我该如何修复我的代码，以便将所有内容都放入一个数组中？

func getFriendRecord () -> [String] {
    var info = ""
    let fetchRequest: NSFetchRequest<Friend> = Friend.fetchRequest()
    do {
        let searchResults = try getContext().fetch(fetchRequest)
        for trans in searchResults as [NSManagedObject] {
            let firstName = String(trans.value(forKey: "firstName") as! String)
            let lastName = String(trans.value(forKey: "lastName") as! String)
            let gender = String(trans.value(forKey: "gender") as! String)
            let age = String(trans.value(forKey: "age") as! String)
            let address = String(trans.value(forKey: "address") as! String)
            info = info + firstName + ", " + lastName + ", " + gender + ", " + age + ", " + address + "\n"
        }
    } catch {
        print("Error with request: \(error)")
    }
    return info
}

Answer 1

如果你想返回一个数组，那么info应该是一个数组:

var info: [String] = []

然后您将向该数组添加其他元素:

let record = [firstName, lastName, gender, age, address].joined(separator: ", ") + "\n"
info.append(record)

我已将其更改为 joined，因为您应该避免在表达式中使用多个 +。在 Swift 中，由于与重载相关的不明显原因，编译速度极慢。没什么问题，只是效果不好。您也可以在这里使用字符串插值，这完全没问题(甚至可能更好一点):

let record = "\(firstName), \(lastName), \(gender), \(age), \(address)\n"