我无法从 plist 键值中解包值
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【中文标题】我无法从 plist 键值中解包值【英文标题】:I can't Unwrap a value from a plist key value 【发布时间】:2020-10-05 18:17:30 【问题描述】:我是 swift 新手,我正在尝试将属性从 nsDictionary 加载到 vTitle
var nsDictionary: NSDictionary?
if let path = Bundle.main.path(forResource: "AppData", ofType: "plist")
nsDictionary = NSDictionary(contentsOfFile: path)
let vTitle:String = nsDictionary["LbVacationsTitle"]
当我调试时,我在 nsDictionary 中看到了正确的键,但我不能只解开一个键的值 LbVacationsTitle 的类型是字符串
【问题讨论】:
你能发布一些调试信息吗?就像path
不是零? nsDictionary
是零吗?你能打印出来吗?此外,在 Swift 4+ 中,建议使用 Codable 和 PropertyList 解码器。
@Larme 路径和 nsDictionary 不是零。 Tx 回复
【参考方案1】:
取决于您的风格偏好...
var nsDictionary: NSDictionary?
if let path = Bundle.main.path(forResource: "AppData", ofType: "plist")
nsDictionary = NSDictionary(contentsOfFile: path)
if let dict = nsDictionary
let vTitle = dict["LbVacationsTitle"] as? String
if let vt = vTitle
// ...
...或...
var nsDictionary: NSDictionary?
if let path = Bundle.main.path(forResource: "AppData", ofType: "plist")
nsDictionary = NSDictionary(contentsOfFile: path)
guard let dict = nsDictionary else
print("Couldn't get a valid dictionary")
return
let vTitle = dict["LbVacationsTitle"] as? String
guard let vt = vTitle else
print("Couldn't find a string matching LbVacationsTitle")
return
// ...
【讨论】:
我用了第二个带保护的,效果很好。发送【参考方案2】:请不要在 Swift 中使用NSDictionary
API 来读取属性列表。
有PropertyListSerialization
(甚至PropertyListDecoder
)
let url = Bundle.main.url(forResource: "AppData", withExtension: "plist")!
let data = try! Data(contentsOf: url)
let dictionary = try! PropertyListSerialization.propertyList(from: data, format: nil) as! [String:Any]
let vTitle = dictionary["LbVacationsTitle"] as! String
由于文件在应用程序包中是不可变的,因此任何崩溃都表明存在设计错误
【讨论】:
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