我在玩苹果的新Swift编程语言,遇到了一些问题…

目前我试图读取一个plist文件,在Objective-C中,我会做以下工作来获取内容作为NSDictionary:

NSString *filePath = [[NSBundle mainBundle] pathForResource:@"Config" ofType:@"plist"];
NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfFile:filePath];

我如何得到一个plist作为一个字典在Swift?

我假设我可以得到路径到plist:

let path = NSBundle.mainBundle().pathForResource("Config", ofType: "plist")

当这工作(如果它是正确的?):我如何获得内容作为一个字典?

还有一个更普遍的问题:

是否可以使用默认的NS*类?我想是的……还是我遗漏了什么?据我所知,默认框架NS*类仍然有效,可以使用吗?


当前回答

斯威夫特3.0

如果你想从.plist读取一个“二维数组”,你可以这样尝试:

if let path = Bundle.main.path(forResource: "Info", ofType: "plist") {
    if let dimension1 = NSDictionary(contentsOfFile: path) {
        if let dimension2 = dimension1["key"] as? [String] {
            destination_array = dimension2
        }
    }
}

其他回答

Plist是一个简单的Swift枚举,用于处理属性列表。

// load an applications info.plist data

let info = Plist(NSBundle.mainBundle().infoDictionary)
let identifier = info["CFBundleIndentifier"].string!

更多的例子:

import Plist

// initialize using an NSDictionary
// and retrieve keyed values

let info = Plist(dict)
let name = info["name"].string ?? ""
let age = info["age"].int ?? 0


// initialize using an NSArray
// and retrieve indexed values

let info = Plist(array)
let itemAtIndex0 = info[0].value


// utility initiaizer to load a plist file at specified path
let info = Plist(path: "path_to_plist_file")

// we support index chaining - you can get to a dictionary from an array via
// a dictionary and so on
// don't worry, the following will not fail with errors in case
// the index path is invalid
if let complicatedAccessOfSomeStringValueOfInterest = info["dictKey"][10]["anotherKey"].string {
  // do something
}
else {
  // data cannot be indexed
}

// you can also re-use parts of a plist data structure

let info = Plist(...)
let firstSection = info["Sections"][0]["SectionData"]
let sectionKey = firstSection["key"].string!
let sectionSecret = firstSection["secret"].int!

Plist.swift

Plist本身非常简单,下面是它的清单,以防你直接引用。

//
//  Plist.swift
//


import Foundation


public enum Plist {

    case dictionary(NSDictionary)
    case Array(NSArray)
    case Value(Any)
    case none

    public init(_ dict: NSDictionary) {
        self = .dictionary(dict)
    }

    public init(_ array: NSArray) {
        self = .Array(array)
    }

    public init(_ value: Any?) {
        self = Plist.wrap(value)
    }

}


// MARK:- initialize from a path

extension Plist {

    public init(path: String) {
        if let dict = NSDictionary(contentsOfFile: path) {
            self = .dictionary(dict)
        }
        else if let array = NSArray(contentsOfFile: path) {
            self = .Array(array)
        }
        else {
            self = .none
        }
    }

}


// MARK:- private helpers

extension Plist {

    /// wraps a given object to a Plist
    fileprivate static func wrap(_ object: Any?) -> Plist {

        if let dict = object as? NSDictionary {
            return .dictionary(dict)
        }
        if let array = object as? NSArray {
            return .Array(array)
        }
        if let value = object {
            return .Value(value)
        }
        return .none
    }

    /// tries to cast to an optional T
    fileprivate func cast<T>() -> T? {
        switch self {
        case let .Value(value):
            return value as? T
        default:
            return nil
        }
    }
}

// MARK:- subscripting

extension Plist {

    /// index a dictionary
    public subscript(key: String) -> Plist {
        switch self {

        case let .dictionary(dict):
            let v = dict.object(forKey: key)
            return Plist.wrap(v)

        default:
            return .none
        }
    }

    /// index an array
    public subscript(index: Int) -> Plist {
        switch self {
        case let .Array(array):
            if index >= 0 && index < array.count {
                return Plist.wrap(array[index])
            }
            return .none

        default:
            return .none
        }
    }

}


// MARK:- Value extraction

extension Plist {

    public var string: String?       { return cast() }
    public var int: Int?             { return cast() }
    public var double: Double?       { return cast() }
    public var float: Float?         { return cast() }
    public var date: Date?         { return cast() }
    public var data: Data?         { return cast() }
    public var number: NSNumber?     { return cast() }
    public var bool: Bool?           { return cast() }


    // unwraps and returns the underlying value
    public var value: Any? {
        switch self {
        case let .Value(value):
            return value
        case let .dictionary(dict):
            return dict
        case let .Array(array):
            return array
        case .none:
            return nil
        }
    }

    // returns the underlying array
    public var array: NSArray? {
        switch self {
        case let .Array(array):
            return array
        default:
            return nil
        }
    }

    // returns the underlying dictionary
    public var dict: NSDictionary? {
        switch self {
        case let .dictionary(dict):
            return dict
        default:
            return nil
        }
    }

}


// MARK:- CustomStringConvertible

extension Plist : CustomStringConvertible {
    public var description:String {
        switch self {
        case let .Array(array): return "(array \(array))"
        case let .dictionary(dict): return "(dict \(dict))"
        case let .Value(value): return "(value \(value))"
        case .none: return "(none)"
        }
    }
}

能在一行内完成吗

    var dict = NSDictionary(contentsOfFile: NSBundle.mainBundle().pathForResource("Config", ofType: "plist"))

如果我想将.plist转换为Swift字典,这是我所做的:

if let path = NSBundle.mainBundle().pathForResource("Config", ofType: "plist") {
  if let dict = NSDictionary(contentsOfFile: path) as? Dictionary<String, AnyObject> {
    // use swift dictionary as normal
  }
}

为Swift 2.0编辑:

if let path = NSBundle.mainBundle().pathForResource("Config", ofType: "plist"), dict = NSDictionary(contentsOfFile: path) as? [String: AnyObject] {
    // use swift dictionary as normal
}

为Swift 3.0编辑:

if let path = Bundle.main.path(forResource: "Config", ofType: "plist"), let dict = NSDictionary(contentsOfFile: path) as? [String: AnyObject] {
        // use swift dictionary as normal
}

我一直在使用Swift 3.0,并希望为更新的语法贡献一个答案。此外,可能更重要的是,我使用PropertyListSerialization对象来做繁重的工作,这比仅仅使用NSDictionary灵活得多,因为它允许数组作为plist的根类型。

下面是我正在使用的plist的截图。这有点复杂,以便显示可用的功率,但这将适用于任何允许的plist类型组合。

正如你所看到的,我正在使用字符串数组:字符串字典来存储网站名称及其对应的URL列表。

如上所述,我使用PropertyListSerialization对象来为我做繁重的工作。此外,Swift 3.0变得更加“Swifty”,所以所有的对象名称都失去了“NS”前缀。

let path = Bundle.main().pathForResource("DefaultSiteList", ofType: "plist")!
let url = URL(fileURLWithPath: path)
let data = try! Data(contentsOf: url)
let plist = try! PropertyListSerialization.propertyList(from: data, options: .mutableContainers, format: nil)

在上面的代码运行后,plist的类型将是Array<AnyObject>,但我们知道它的实际类型,所以我们可以将它强制转换为正确的类型:

let dictArray = plist as! [[String:String]]
// [[String:String]] is equivalent to Array< Dictionary<String, String> >

现在我们可以以自然的方式访问Array of String:String dictionary的各种属性。希望将它们转换为实际的强类型结构体或类;)

print(dictArray[0]["Name"])

你可以使用它,我在github https://github.com/DaRkD0G/LoadExtension中创建了一个简单的字典扩展

extension Dictionary {
    /**
        Load a Plist file from the app bundle into a new dictionary

        :param: File name
        :return: Dictionary<String, AnyObject>?
    */
    static func loadPlistFromProject(filename: String) -> Dictionary<String, AnyObject>? {

        if let path = NSBundle.mainBundle().pathForResource("GameParam", ofType: "plist") {
            return NSDictionary(contentsOfFile: path) as? Dictionary<String, AnyObject>
        }
        println("Could not find file: \(filename)")
        return nil
    }
}

你可以用它来计算负载

/**
  Example function for load Files Plist

  :param: Name File Plist
*/
func loadPlist(filename: String) -> ExampleClass? {
    if let dictionary = Dictionary<String, AnyObject>.loadPlistFromProject(filename) {
        let stringValue = (dictionary["name"] as NSString)
        let intergerValue = (dictionary["score"] as NSString).integerValue
        let doubleValue = (dictionary["transition"] as NSString).doubleValue

        return ExampleClass(stringValue: stringValue, intergerValue: intergerValue, doubleValue: doubleValue)
    }
    return nil
}