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
在swift 3.0从Plist读取。
func readPropertyList() {
var propertyListFormat = PropertyListSerialization.PropertyListFormat.xml //Format of the Property List.
var plistData: [String: AnyObject] = [:] //Our data
let plistPath: String? = Bundle.main.path(forResource: "data", ofType: "plist")! //the path of the data
let plistXML = FileManager.default.contents(atPath: plistPath!)!
do {//convert the data to a dictionary and handle errors.
plistData = try PropertyListSerialization.propertyList(from: plistXML, options: .mutableContainersAndLeaves, format: &propertyListFormat) as! [String:AnyObject]
} catch {
print("Error reading plist: \(error), format: \(propertyListFormat)")
}
}
阅读更多 如何在swift中使用属性列表(. plist)。
其他回答
以下是我找到的解决方案:
let levelBlocks = NSDictionary(contentsOfFile: NSBundle.mainBundle().pathForResource("LevelBlocks", ofType: "plist"))
let test: AnyObject = levelBlocks.objectForKey("Level1")
println(test) // Prints the value of test
我将测试类型设置为AnyObject，以关闭关于可能发生的意外推断的警告。
而且，它必须在类方法中完成。
访问并保存已知类型的特定值:
let value = levelBlocks.objectForKey("Level1").objectForKey("amount") as Int
println(toString(value)) // Converts value to String and prints it
我已经创建了一个简单的字典初始化器替换NSDictionary(contentsOfFile: path)。只要去掉NS。
extension Dictionary where Key == String, Value == Any {
public init?(contentsOfFile path: String) {
let url = URL(fileURLWithPath: path)
self.init(contentsOfURL: url)
}
public init?(contentsOfURL url: URL) {
guard let data = try? Data(contentsOf: url),
let dictionary = (try? PropertyListSerialization.propertyList(from: data, options: [], format: nil) as? [String: Any]) ?? nil
else { return nil }
self = dictionary
}
}
你可以这样使用它:
let filePath = Bundle.main.path(forResource: "Preferences", ofType: "plist")!
let preferences = Dictionary(contentsOfFile: filePath)!
UserDefaults.standard.register(defaults: preferences)
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"])
Swift 4.0 iOS 11.2.6列表解析和代码解析它，基于https://stackoverflow.com/users/3647770/ashok-r上面的答案。
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<array>
<dict>
<key>identity</key>
<string>blah-1</string>
<key>major</key>
<string>1</string>
<key>minor</key>
<string>1</string>
<key>uuid</key>
<string>f45321</string>
<key>web</key>
<string>http://web</string>
</dict>
<dict>
<key>identity</key>
<string></string>
<key>major</key>
<string></string>
<key>minor</key>
<string></string>
<key>uuid</key>
<string></string>
<key>web</key>
<string></string>
</dict>
</array>
</plist>
do {
let plistXML = try Data(contentsOf: url)
var plistData: [[String: AnyObject]] = [[:]]
var propertyListFormat = PropertyListSerialization.PropertyListFormat.xml
do {
plistData = try PropertyListSerialization.propertyList(from: plistXML, options: .mutableContainersAndLeaves, format: &propertyListFormat) as! [[String:AnyObject]]
} catch {
print("Error reading plist: \(error), format: \(propertyListFormat)")
}
} catch {
print("error no upload")
}
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)"
}
}
}
