我正在开发一个 iPhone 应用程序
我像这样从 root.plist 中读取了一个密钥：
NSString *Key1Var = [[NSUserDefaults standardUserDefaults] stringForKey:@"Key1"];
("Key1" 是一个PSMultiValueSpecifier 已经在root.plist 中设置了默认字符串值)
一旦用户进行设置，就可以正常工作。
但是，如果用户在进行任何设置之前运行应用程序，他将获得“Key1”的nil。
在这种情况下，我期待我为“Key1”设置的默认值。
我需要做什么，
让用户不用做设置，让应用程序第一次运行？
问候， 哈里什
【问题讨论】：
标签： iphone objective-c xcode
请参阅this question 以获得完整的解决方案。
您实际上想在访问设置之前运行此代码：
- (void)registerDefaultsFromSettingsBundle {
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];
}
}
[[NSUserDefaults standardUserDefaults] registerDefaults:defaultsToRegister];
[defaultsToRegister release];
}
这会将默认值加载到 standardUserDefaults 对象中，因此您将不再返回 nil 值，并且您不必在代码中复制默认设置。
【讨论】：
stringByAppendingPathComponent 不可用的错误。
我会在发布后尽早执行此操作，然后再尝试获取我的设置：
userDefaultsValuesPath=[[NSBundle mainBundle] pathForResource:@"UserDefaults"
ofType:@"plist"];
userDefaultsValuesDict=[NSDictionary dictionaryWithContentsOfFile:userDefaultsValuesPath];
// set them in the standard user defaults
[[NSUserDefaults standardUserDefaults] registerDefaults:userDefaultsValuesDict];
if (![[NSUserDefaults standardUserDefaults] synchronize])
NSLog(@"not successful in writing the default prefs");
【讨论】：
-pathForResource:。如果由于某种原因您不能这样做，您可以将 plist 复制到您的应用程序包的资源以及设置包的资源中。
如果有人需要的话，基于Mike Weller's 原始解决方案的 Swift 3 版本：
static func registerDefaultsFromSettingsBundle() {
guard let settingsBundle = Bundle.main.url(forResource: "Settings", withExtension: "bundle") else {
print("Could not find Settings.bundle")
return
}
guard let settings = NSDictionary(contentsOf: settingsBundle.appendingPathComponent("Root.plist")) else {
print("Couldn't find Root.plist in settings bundle")
return
}
guard let preferences = settings.object(forKey: "PreferenceSpecifiers") as? [[String: AnyObject]] else {
print("Root.plist has an invalid format")
return
}
var defaultsToRegister = [String: AnyObject]()
for var p in preferences {
if let k = p["Key"] as? String, let v = p["DefaultValue"] {
print("Registering " + v.debugDescription + " for key " + k)
defaultsToRegister[k] = v as AnyObject
}
}
UserDefaults.standard.register(defaults: defaultsToRegister)
}
【讨论】：
这是我在 iOS 7 中使用的代码，很大程度上基于上面Mike Weller 的代码。
将此方法放在您的 AppDelegate.m 中：
- (void)registerDefaultsFromSettingsBundleWithPlist:(NSString *)plist {
NSString *settingsBundle = [[NSBundle mainBundle] pathForResource:@"Settings" ofType:@"bundle"];
if(!settingsBundle) {
NSLog(@"Could not find Settings.bundle");
return;
}
NSString *bundle = [NSString stringWithFormat:@"%@.plist",plist];
NSDictionary *settings = [NSDictionary dictionaryWithContentsOfFile:[settingsBundle stringByAppendingPathComponent:bundle]];
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];
}
}
[[NSUserDefaults standardUserDefaults] registerDefaults:defaultsToRegister];
//[defaultsToRegister release];
}
然后从代码早期的某个位置（例如 didFinishLaunchingWithOptions）为您正在使用的每个设置文件（用于嵌套设置）调用它：
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
//register default settings into NSUserDefaults
@try {
[self registerDefaultsFromSettingsBundleWithPlist:@"Root"];
[self registerDefaultsFromSettingsBundleWithPlist:@"Chat"];
[self registerDefaultsFromSettingsBundleWithPlist:@"IVR"];
[self registerDefaultsFromSettingsBundleWithPlist:@"Video"];
}
@catch (NSException * e) {
NSLog(@"Exception: %@", e);
NSLog(@"Try adding the Default Value field to each preference item in the Settings.bundle plist files.");
}
@finally {
}
...
【讨论】：
我已将Mike Weller 的解决方案翻译成 Swift 2.0/iOS 9 并使其适用于我的应用程序：
func registerDefaultsFromSettingsBundle() {
guard let settingsBundle = NSBundle.mainBundle().URLForResource("Settings", withExtension:"bundle") else {
NSLog("Could not find Settings.bundle")
return;
}
guard let settings = NSDictionary(contentsOfURL: settingsBundle.URLByAppendingPathComponent("Root.plist")) else {
NSLog("Could not find Root.plist in settings bundle")
return
}
guard let preferences = settings.objectForKey("PreferenceSpecifiers") as? [[String: AnyObject]] else {
NSLog("Root.plist has invalid format")
return
}
var defaultsToRegister = [String: AnyObject]()
for var p in preferences {
if let k = p["Key"] as? String, v = p["DefaultValue"] {
NSLog("%@", "registering \(v) for key \(k)")
defaultsToRegister[k] = v
}
}
NSUserDefaults.standardUserDefaults().registerDefaults(defaultsToRegister)
}
【讨论】：
在我的应用程序委托中，我重写了+initialize 方法并注册了新的应用程序默认首选项。
例如：
+ (void) initialize {
if ([self class] == [MyAppDelegate class]) {
// initialize user defaults dictionary
BOOL isFirstTimeRun = YES;
BOOL isKeychainTurnedOn = NO;
BOOL isSSLTurnedOn = YES;
NSString *testURLString = @"http://stackoverflow.com";
NSMutableDictionary *resourceDict = [NSMutableDictionary dictionary];
[resourceDict setObject:[NSNumber numberWithBool:isFirstTimeRun] forKey:kIsFirstTimeRunKey];
[resourceDict setObject:[NSNumber numberWithBool:isKeychainTurnedOn] forKey:kIsKeychainTurnedOnKey];
[resourceDict setObject:[NSNumber numberWithBool:isSSLTurnedOn] forKey:kIsSSLTurnedOnKey];
[resourceDict setObject:testURLString forKey:kTestURLString];
[[NSUserDefaults standardUserDefaults] registerDefaults:resourceDict];
}
}
【讨论】：
NSBundle* mainBundle = [NSBundle mainBundle];
// Reads the value of the custom key I added to the Info.plist
NSString *value = [mainBundle objectForInfoDictionaryKey:@"key"];
//Log the value
NSLog(@"Value = %@", value);
// Get the value for the "Bundle version" from the Info.plist
[mainBundle objectForInfoDictionaryKey:@"CFBundleVersion"];
// Get the bundle identifier
[mainBundle bundleIdentifier];
【讨论】：