Question

我要通过此语句在UserDefaults中访问用户数组中的“全名”

Optional({ message = Hello; success = true; user = { fullname = "xyz"; id = 0; }; })

if currentUser?[""] != nil {

// do something 
}

Answer 1

让我们假设可选的Optional({ message = Hello; success = true; user = { fullname = “xyz”; id = 0; }; })设置为currentUser：

if let currentUser = currentUser { //get a not optional value of currentUser
    let fullname = currentUser["fullname"] //you will get an optional here
    if fullname != nil {
       print("Full name: \(fullname!)")
    } else {
       print("Full name wasn't provided")
    }
}

但可以在一行检查中提供相同的内容：

if let currentUser = currentUser, let fullname = currentUser["fullname"] {
    print("Full name: \(fullname)"
}

有关您可以在文档https://developer.apple.com/documentation/swift/optional或某些博客文章中阅读的可选内容的更多信息，我建议您使用以下内容：https://hackernoon.com/swift-optionals-explained-simply-e109a4297298

Answer 2

快捷键3

商店

UserDefaults.standard.set(true, forKey: "Key") //Bool
UserDefaults.standard.set(1, forKey: "Key")  //Integer
UserDefaults.standard.set("TEST", forKey: "Key") //setObject

检索

UserDefaults.standard.bool(forKey: "Key")
UserDefaults.standard.integer(forKey: "Key")
UserDefaults.standard.string(forKey: "Key")

检索对象

var returnValue: [datatype]? = UserDefaults.standard.object(forKey: "key_name") as? [datatype]

删除

UserDefaults.standard.removeObject(forKey: "Key")

删除所有键

if let appDomain = Bundle.main.bundleIdentifier {
UserDefaults.standard.removePersistentDomain(forName: appDomain)
}

如何访问存储在UserDefaults中的对象的属性

2 个答案: