objective-c 如何在 Swift 中编写 init 方法？
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How to write init method in Swift?
提问by Vineesh TP
I want to write an initmethod in Swift. Here I initialize an NSObjectclass in Objective-C:
我想init用 Swift编写一个方法。这里我NSObject在 Objective-C 中初始化了一个类：
-(id)initWithNewsDictionary:(NSDictionary *)dictionary
{
self = [super init];
if (self) {
self.title = dictionary[@"title"];
self.shortDescription = dictionary[@"description"];
self.newsDescription = dictionary[@"content:encoded"];
self.link = dictionary[@"link"];
self.pubDate = [self getDate:dictionary[@"pubDate"]];
}
return self;
}
How can I write this method in Swift ?
如何在 Swift 中编写此方法？
回答by holex
that could be good bases for your class, I guess:
我想这可能是您班级的良好基础：
class MyClass {
// you may need to set the proper types in accordance with your dictionarty's content
var title: String?
var shortDescription: String?
var newsDescription: String?
var link: NSURL?
var pubDate: NSDate?
//
init () {
// uncomment this line if your class has been inherited from any other class
//super.init()
}
//
convenience init(_ dictionary: Dictionary<String, AnyObject>) {
self.init()
title = dictionary["title"] as? NSString
shortDescription = dictionary["shortDescription"] as? NSString
newsDescription = dictionary["newsDescription"] as? NSString
link = dictionary["link"] as? NSURL
pubDate = self.getDate(dictionary["pubDate"])
}
//
func getDate(object: AnyObject?) -> NSDate? {
// parse the object as a date here and replace the next line for your wish...
return object as? NSDate
}
}
advanced-mode
高级模式
I would like to avoid to copy-pand-paste the keys in a project, so I'd put the possible keys into e.g. an enumlike this:
我想避免在项目中复制粘贴键，所以我将可能的键放入例如enum这样的：
enum MyKeys : Int {
case KeyTitle, KeyShortDescription, KeyNewsDescription, KeyLink, KeyPubDate
func toKey() -> String! {
switch self {
case .KeyLink:
return "title"
case .KeyNewsDescription:
return "newsDescription"
case .KeyPubDate:
return "pubDate"
case .KeyShortDescription:
return "shortDescription"
case .KeyTitle:
return "title"
default:
return ""
}
}
}
and you can improve your convenience init(...)method like e.g. this, and in the future you can avoid any possible mistyping of the keys in your code:
并且您可以convenience init(...)像这样改进您的方法，将来您可以避免在代码中输入任何可能的键错误：
convenience init(_ dictionary: Dictionary<String, AnyObject>) {
self.init()
title = dictionary[MyKeys.KeyTitle.toKey()] as? NSString
shortDescription = dictionary[MyKeys.KeyShortDescription.toKey()] as? NSString
newsDescription = dictionary[MyKeys.KeyNewsDescription.toKey()] as? NSString
link = dictionary[MyKeys.KeyLink.toKey()] as? NSURL
pubDate = self.getDate(dictionary[MyKeys.KeyPubDate.toKey()])
}
NOTE: that is just a raw idea of how you could do it, it is not necessary to use conveniece initializer at all, but it looked obvious choice regarding I don't know anything about your final class – you have shared one method only.
注意：这只是一个关于如何做到这一点的原始想法，根本没有必要使用方便的初始化程序，但它看起来很明显，因为我对你的最终课程一无所知——你只共享了一个方法。
回答by Shai
class myClass {
var text: String
var response: String?
init(text: String) {
self.text = text
}
}
请参阅Swift：初始化
回答by abdul sathar
Do not need for call this method from other class it will get called automatically
不需要从其他类调用此方法它会自动调用
override init()
{
super.init()
// synthesize.delegate = self
// println("my array elements are \(readingData)")
}
回答by CW0007007
try:
尝试：
initWithDictionary(dictionary : NSDictionary) {
init()
self.title = "... etc"
}
Source:
来源：
https://docs.swift.org/swift-book/LanguageGuide/Initialization.html
https://docs.swift.org/swift-book/LanguageGuide/Initialization.html
