快速更改语言

Question

现在我知道苹果不推荐这个。

一般来说，您不应在应用程序中更改 iOS 系统语言（通过使用 AppleLanguages 首选项键）。这违背了在设置应用程序中切换语言的基本 iOS 用户模型，并且还使用了未记录的首选项键，这意味着在将来的某个时候，键名可能会更改，这会破坏您的应用程序。

但是，这是一个动态更改语言的应用程序，请相信我。我也知道这里有人问过这个问题：Changing language on the fly, in running iOS, programmatically。然而，这已经过时了，我想知道是否有任何更新、更好或更简单的方法来做到这一点。目前在我的应用程序中，我有一个语言选择屏幕。单击此视图中的按钮会调用与按钮关联的语言的以下函数：

 func changeLang(language: String) {

    if language != (currentLang as! String?)! {
        func handleCancel(alertView: UIAlertAction!)
        {

        }
        var alert = UIAlertController(title: NSLocalizedString("language", comment: "Language"), message: NSLocalizedString("languageWarning", comment: "Warn User of Language Change Different Than Defaults"), preferredStyle: UIAlertControllerStyle.Alert)

        alert.addAction(UIAlertAction(title: "Cancel", style: UIAlertActionStyle.Cancel, handler:handleCancel))
        alert.addAction(UIAlertAction(title: "Yes", style: UIAlertActionStyle.Default, handler:{ (UIAlertAction) in

            NSUserDefaults.standardUserDefaults().setObject([language], forKey: "AppleLanguages")
            NSUserDefaults.standardUserDefaults().synchronize()
            println(self.currentLang)

            let alert = UIAlertView()
            alert.title = NSLocalizedString("language", comment: "Sign In Failed")
            alert.message = NSLocalizedString("languageChangeNotification", comment: "Notify of language change")
            alert.addButtonWithTitle(NSLocalizedString("ok", comment: "Okay"))
            alert.show()

            self.performSegueWithIdentifier("welcome", sender: AnyObject?())


        }))
        self.presentViewController(alert, animated: true, completion: {
        })
    } else {
        self.performSegueWithIdentifier("welcome", sender: AnyObject?())
    }

}

例子：

@IBAction func english(sender: UIButton) {
        changeLang("en")

    }

如果用户选择了与他们自己不同的语言，他们会收到确认警报，然后要求重新启动该设备。这就是我想要改变的。在应用程序重新启动之前，这部分 NSUSerDefaults 似乎不会同步。证据：

let currentLang: AnyObject? = NSLocale.preferredLanguages()[0]
println(currentLang)
// Prints english
changeLang("zh-Hans")
println(currentLang)
// Prints english still until restart 

苹果目前的国际化系统很好，我打算使用它。但是，我如何可以通过强制更新 NSUSerDefaults 来动态更改语言？

编辑：我建议现在使用这个library 来执行此操作。祝你好运！

Answer 1

基本上你必须教你如何通过加载不同的bundle文件来切换语言。

我将我的Objective-C code 翻译成 Swift — 保持 NSBundle 类别不变。

结果是一个视图控制器类，它提供了一个languageDidChange() 方法用于覆盖。

---

NSBundle+Language.h

#import <Foundation/Foundation.h>

@interface NSBundle (Language)
+(void)setLanguage:(NSString*)language;

@end

---

NSBundle+Language.m

#import "NSBundle+Language.h"
#import <objc/runtime.h>

static const char associatedLanguageBundle=0;

@interface PrivateBundle : NSBundle
@end

@implementation PrivateBundle
-(NSString*)localizedStringForKey:(NSString *)key
                            value:(NSString *)value
                            table:(NSString *)tableName
{
    NSBundle* bundle=objc_getAssociatedObject(self, &associatedLanguageBundle);
    return bundle ? [bundle localizedStringForKey:key
                                            value:value
                                            table:tableName] : [super localizedStringForKey:key
                                                                                      value:value
                                                                                      table:tableName];
}
@end

@implementation NSBundle (Language)
+(void)setLanguage:(NSString*)language
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        object_setClass([NSBundle mainBundle],[PrivateBundle class]);
    });

    objc_setAssociatedObject([NSBundle mainBundle], &associatedLanguageBundle, language ?
                             [NSBundle bundleWithPath:[[NSBundle mainBundle] pathForResource:language ofType:@"lproj"]] : nil, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
@end

---

AppDelegate.swift

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

        NSNotificationCenter.defaultCenter().addObserver(self, selector: "languageWillChange:", name: "LANGUAGE_WILL_CHANGE", object: nil)

        let targetLang = NSUserDefaults.standardUserDefaults().objectForKey("selectedLanguage") as? String

        NSBundle.setLanguage((targetLang != nil) ? targetLang : "en")
        return true
    }

    func languageWillChange(notification:NSNotification){
        let targetLang = notification.object as! String
        NSUserDefaults.standardUserDefaults().setObject(targetLang, forKey: "selectedLanguage")
        NSBundle.setLanguage(targetLang)
        NSNotificationCenter.defaultCenter().postNotificationName("LANGUAGE_DID_CHANGE", object: targetLang)
    }    
}

---

BaseViewController.swift

import UIKit



class BaseViewController: UIViewController {

    @IBOutlet weak var englishButton: UIButton!
    @IBOutlet weak var spanishButton: UIButton!

    deinit{
        NSNotificationCenter.defaultCenter().removeObserver(self)
    }
    override func viewDidLoad() {
        super.viewDidLoad()
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "languageDidChangeNotification:", name: "LANGUAGE_DID_CHANGE", object: nil)
        languageDidChange()

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func switchLanguage(sender: UIButton) {

        var localeString:String?
        switch sender {
        case englishButton: localeString = "en"
        case spanishButton: localeString = "es"
        default: localeString = nil
        }


        if localeString != nil {
            NSNotificationCenter.defaultCenter().postNotificationName("LANGUAGE_WILL_CHANGE", object: localeString)
        }
    }


    func languageDidChangeNotification(notification:NSNotification){
        languageDidChange()
    }

    func languageDidChange(){

    }


}

---

ViewController.swift

import UIKit

class ViewController: BaseViewController {

    @IBOutlet weak var helloLabel: UILabel!
    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func languageDidChange() {
        super.languageDidChange()
        self.helloLabel.text = NSLocalizedString("Hello", comment: "")

    }
}

---

除了使用 BaseViewController 的子类，您的视图控制器还可以发布“LANGUAGE_WILL_CHANGE”并监听“LANGUAGE_DID_CHANGE”

我把完整的项目推到这里了：ImmediateLanguageSwitchSwift

Answer 2

正如“vikingosegundo”回答的那样，上面的类别属于Objective c 所以这里是Swift extension版本

import ObjectiveC

private var associatedLanguageBundle:Character = "0"

class PrivateBundle: Bundle {
    override func localizedString(forKey key: String, value: String?, table tableName: String?) -> String {
        let bundle: Bundle? = objc_getAssociatedObject(self, &associatedLanguageBundle) as? Bundle
        return (bundle != nil) ? (bundle!.localizedString(forKey: key, value: value, table: tableName)) : (super.localizedString(forKey: key, value: value, table: tableName))

    }
}

extension Bundle {
    class func setLanguage(_ language: String) {
        var onceToken: Int = 0

        if (onceToken == 0) {
            /* TODO: move below code to a static variable initializer (dispatch_once is deprecated) */
            object_setClass(Bundle.main, PrivateBundle.self)
        }
        onceToken = 1
        objc_setAssociatedObject(Bundle.main, &associatedLanguageBundle, (language != nil) ? Bundle(path: Bundle.main.path(forResource: language, ofType: "lproj") ?? "") : nil, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
    }
}

剩下的代码和“vikingosegundo”提到的一样

随时欢迎指正:)

Answer 3

使用这行代码，它会在不关闭应用程序的情况下更改布局。 从右到左

UIView.appearance().semanticContentAttribute = .forceRightToLeft

对于从左到右翻转

UIView.appearance().semanticContentAttribute = .forceLeftToRight

如果您想更改文本字段布局或文本更改，请使用此代码，因为我遇到了这个问题。文本字段的文本没有改变布局。检查此代码以更改文本字段文本的布局。

extension UITextField {
  open override func awakeFromNib() {
super.awakeFromNib()
  if UserDefaults.languageCode == "ar" {
    if textAlignment == .natural {
        self.textAlignment = .right
    }
  }
 }
}