Ios 将数据从应用程序委托传递到视图控制器

我需要将一个字符串从App delegate传递到我的初始视图控制器，

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有人能给我列出最好的方法吗？我也试着用NS用户默认值保存和检索，但我没有正常工作

界面：

@interface MyAppDelegate : NSObject  {
  NSString *myString;
}
@property (nonatomic, retain) NSString *myString;
...
@end

let yourViewController = self.window?.rootViewController as? YourViewController
yourViewController?.passData(YOUR_DATA) // pass data
let data = yourViewController?.getData() // access data

let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.passData(YOUR_DATA) // pass data
let data = appDelegate.getData() // access data

private var data : String? // String? or any type you want
func getData() -> String? {
    return data
}
func passData(_ data : String?) {
    self.data = data
}

在应用程序代理的.m文件中，您将写入：

@implementation MyAppDelegate
@synthesize myString;
    myString = some string;
@end

然后，在viewcontroller.m文件中，您可以获取：

MyAppDelegate *appDelegate = (MyAppDelegate*)[[UIApplication sharedApplication] delegate];
someString = appDelegate.myString;  //..to read
appDelegate.myString = some NSString;     //..to write

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您可以通过应用程序代理访问根视图控制器，如下所示：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    MyViewController* mainController = (MyViewController*)  self.window.rootViewController;
    [mainController passData:@"hello"];

    return YES;
}

这是给斯威夫特的：

视图控制器

let appDelegate = UIApplication.sharedApplication().delegate as AppDelegate

var model : CloudData = self.appDelegate.getCloudData()

此外，如果您有一个要在视图控制器之间传递的对象（例如，我有一个要共享的CloudKit数据），请将其添加到应用程序委托中：

    /* Function for any view controller to grab the instantiated CloudDataObject */
func getCloudData() ->CloudData{
    return cloudDataObject
}

然后回到视图控制器

let appDelegate = UIApplication.sharedApplication().delegate as AppDelegate

var model : CloudData = self.appDelegate.getCloudData()

使用Swift 4.2：

将数据从AppDelegate传递到ViewController:

@interface MyAppDelegate : NSObject  {
  NSString *myString;
}
@property (nonatomic, retain) NSString *myString;
...
@end

let yourViewController = self.window?.rootViewController as? YourViewController
yourViewController?.passData(YOUR_DATA) // pass data
let data = yourViewController?.getData() // access data

let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.passData(YOUR_DATA) // pass data
let data = appDelegate.getData() // access data

private var data : String? // String? or any type you want
func getData() -> String? {
    return data
}
func passData(_ data : String?) {
    self.data = data
}

将数据从ViewController传递到AppDelegate:

@interface MyAppDelegate : NSObject  {
  NSString *myString;
}
@property (nonatomic, retain) NSString *myString;
...
@end

let yourViewController = self.window?.rootViewController as? YourViewController
yourViewController?.passData(YOUR_DATA) // pass data
let data = yourViewController?.getData() // access data

let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.passData(YOUR_DATA) // pass data
let data = appDelegate.getData() // access data

private var data : String? // String? or any type you want
func getData() -> String? {
    return data
}
func passData(_ data : String?) {
    self.data = data
}

向ViewController或AppDelegate添加以下代码：

@interface MyAppDelegate : NSObject  {
  NSString *myString;
}
@property (nonatomic, retain) NSString *myString;
...
@end

let yourViewController = self.window?.rootViewController as? YourViewController
yourViewController?.passData(YOUR_DATA) // pass data
let data = yourViewController?.getData() // access data

let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.passData(YOUR_DATA) // pass data
let data = appDelegate.getData() // access data

private var data : String? // String? or any type you want
func getData() -> String? {
    return data
}
func passData(_ data : String?) {
    self.data = data
}

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这篇文章救了我一命。非常感谢你的朋友。你的答案应该包含大写字母：“我的方法是危险的和糟糕的做法，因为它破坏了封装并创建了全局状态。”这不是出于某种原因。原因非常明确，因为应用程序委托的目的是响应应用程序状态的更改。使用它作为数据和常量的转储地是一种糟糕的形式，会导致依赖于一个在MVC范例中不是贡献公民的对象。passData从哪里来？如何申报？