多值类型设置捆绑字段始终返回 null

问题描述

第一次启动应用程序时，我在从设置包中检索默认值时遇到问题.所有非多值字段都正确返回默认值.所有多值字段都返回 NULL.我用来检索当前值的代码:

I have a problem retrieving default values from the settings bundle when first launching an App. All non-multivalue fields return the default correctly. All multivalue fields return NULL. The code I am using to retrieve the current value:

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *upt=[defaults objectForKey:@"upthreshold"];

Root.plist 中的相关部分是:

The relevant section from Root.plist is:

                <dict>
                    <key>Title</key>
                    <string>Update Threshold</string>
                    <key>Type</key>
                    <string>PSMultiValueSpecifier</string>
                    <key>Key</key>
                    <string>upthreshold</string>
                    <key>DefaultValue</key>
                    <string>15</string>
                    <key>Titles</key>
                    <array>
                            <string>2 km</string>
                            <string>5 km</string>
                            <string>10 km</string>
                            <string>15 km</string>
                            <string>25 km</string>
                            <string>50 km</string>
                            <string>75 km</string>
                            <string>100 km</string>
                            <string>150 km</string>
                            <string>250 km</string>
                            <string>500 km</string>
                            <string>1000 km</string>
                    </array>
                    <key>Values</key>
                    <array>
                            <string>2</string>
                            <string>5</string>
                            <string>10</string>
                            <string>15</string>
                            <string>25</string>
                            <string>50</string>
                            <string>75</string>
                            <string>100</string>
                            <string>150</string>
                            <string>250</string>
                            <string>500</string>
                            <string>1000</string>
                    </array>
            </dict>

我希望15"会作为当前值返回，因为它被设置为默认值.多值字段是否需要一些不同的处理?正如我之前所说，在此之前有 6 个字段可以正确返回它们的值.此字段和以下 2 个多值字段没有.多值字段的定义都相同.

I would expect that "15" would come back as the current value as it is set to the default value. Is there some different processing required for Multivalue fields? As I said previously, there are 6 fields prior to this that return their values correctly. This field and the following 2 Multivalue fields do not. The multivalue fields are all defined the same.

推荐答案

如果用户未在设置应用程序中更改该值，则没有设置.设置包中指定的默认值只是设置应用程序中显示的默认值

If the value wasn't changed by the user in the settings app there is no setting.The default value specified in the settings bundle is only the default for display in the settings app

您必须手动注册默认值.NSUserdefaults 不使用设置包中的默认值.
使用类似这样的东西，将它添加到您的应用程序的开头(在您访问用户默认值之前).
注册用户默认值不会保存到磁盘或任何东西.每次启动应用程序时都必须注册它们.

you have to manually register your default values. NSUserdefaults doesn't use the defaults from the settings bundle.
Use something like this, add it at the beginning of your app (before you access the userdefaults).
Registered Userdefaults are not saved to disk or anything. You have to register them every time you start the app.

NSDictionary *userDefaultsDefaults = [NSDictionary dictionaryWithObjectsAndKeys:
                                      @"15", @"upthreshold",
                                      nil];
[[NSUserDefaults standardUserDefaults] registerDefaults:userDefaultsDefaults];

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