如何从目标c中的settings.bundle中检索值？ [英] How to retrieve values from settings.bundle in objective c?

问题描述

我创建了一个项目，用于设置和检索 settings.bundle 中的值。我还在 settings.bundle 文件中设置了一些默认值。现在的问题是我将值检索为

I have created a project that set and retrieve values from settings.bundle. I have also set some defaults values in settings.bundle file. Now the problem is when I retrieve values as

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
loginName.text = [defaults objectForKey:@"login_name"];

第一次显示null，但是在iPhone应用程序设置中设置了值。
如果我更改值或手动设置，则可以正确检索值。

for the first time it shows null, but the values get set in iPhone application settings. If I change the values or set it manually, then values are retrieved properly.

帮帮我

推荐答案

虽然您定义了默认设置，但它们并未真正存储为值。它们默认存储。如果您尝试读取它，则该值为null。默认设置是值为的另一个属性。但它并不意味着将默认值写为默认值。

Although you define the defaults settings, they are not really stored as a value. They are stored as default. If you try to read it, the value is null. Default setting is another property as value is. But it doesnt mean that will write the default value as a default.

我做的是，首先，检查是否有一些设置，（我确定应该有）值）有任何存储在其上的东西。如果它没有任何东西，那么我写下所有的默认值。

What I do is, first, check if some setting,(that I'm sure that should have a value) has anything stored on it. If it doesn't have anything then I write all the defaults.

这是一个例子。

on AppDelegate.m我检查 email_notificaciones_preference 是否有值，如果没有，我会将所有默认设置写入每个设置。

on AppDelegate.m I check if email_notificaciones_preference has a value, if not, I write ALL default settings to each setting.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
    NSUserDefaults * standardUserDefaults = [NSUserDefaults standardUserDefaults];
    NSString * email_notificaciones_preference = [standardUserDefaults objectForKey:@"email_notificaciones_preference"];
    if (!email_notificaciones_preference) {
        [self registerDefaultsFromSettingsBundle];
    }

}

这个函数是我用的写默认值给每个元素。

This function is what I use to write defaults to each element.

#pragma NSUserDefaults
- (void)registerDefaultsFromSettingsBundle {
    // this function writes default settings as settings
    NSString *settingsBundle = [[NSBundle mainBundle] pathForResource:@"Settings" ofType:@"bundle"];
    if(!settingsBundle) {
        NSLog(@"Could not find Settings.bundle");
        return;
    }

    NSDictionary *settings = [NSDictionary dictionaryWithContentsOfFile:[settingsBundle stringByAppendingPathComponent:@"Root.plist"]];
    NSArray *preferences = [settings objectForKey:@"PreferenceSpecifiers"];

    NSMutableDictionary *defaultsToRegister = [[NSMutableDictionary alloc] initWithCapacity:[preferences count]];
    for(NSDictionary *prefSpecification in preferences) {
        NSString *key = [prefSpecification objectForKey:@"Key"];
        if(key) {
            [defaultsToRegister setObject:[prefSpecification objectForKey:@"DefaultValue"] forKey:key];
            NSLog(@"writing as default %@ to the key %@",[prefSpecification objectForKey:@"DefaultValue"],key);
        }
    }

    [[NSUserDefaults standardUserDefaults] registerDefaults:defaultsToRegister];

}

希望有所帮助。

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