iOS:在 NSUserDefaults 中使用布尔值

问题描述

当我的应用程序的 rootViewController 加载时，我希望能够检查用户登录凭据是否已保存到 NSUserDefaults.

When the rootViewController of my application is loaded, I want to be able to check whether or not the users login credentials have been saved to NSUserDefaults.

基本上，当用户加载应用程序并且他/她没有保存她的登录凭据时，将推送 modalAlertView 并且用户将能够适当地保存他们的凭据.这会将那些 UITextField 字符串保存到相应的 NSUserDefault 对象中.但是，是否有可能在完成此保存后，我可以创建一个 NSUserDefault 对象，它是一个布尔值并将值更改为是?

Basically, when the user loads the application and he/she doesn't have her login credentials saved, a modalAlertView will be pushed and the user will be able to save their credentials appropriately. This saves those UITextField strings to a respective NSUserDefault object. However, is it possible, that when this saving is done, I can create an NSUserDefault object which is a boolean and change the value to a yes?

意味着布尔值已经设置为否，并且当用户保存其登录凭据时，它也会将布尔值更改为是?

Meaning that the boolean is already set to no, and when the user saves their login credentials, it also changes the boolean to a yes?

推荐答案

您可以使用以下方法设置布尔值:

You can set your boolean by using:

[[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"logged_in"];
[[NSUserDefaults standardUserDefaults] synchronize];

并使用以下代码阅读:

if(![[NSUserDefaults standardUserDefaults] boolForKey:@"logged_in"]) {
    [self displayLogin];
} else {
    [self displayMainScreen];
}

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