[iOS] 刪除 User Defaults
很多時候我們會把資料儲存在User Defaults，也就是本機端，只要App不被刪掉，那麼每次重新開啟App，就能再從User Defaults取得先前所儲存的資料。
有某時候我們需要把User Defaults給清空，比如要給其它帳號使用，此時登出A就要將A所儲存的User Defaults給清除乾淨，而登入B後又是全新沒有受污染的User Defaults。
該怎麼做呢？以下的code就能刪除所有存在User Defaults中的key，不過卻不會刪掉系統預設的key呢！
/**
Theme: Delete User Defaults
IDE: Xcode 7
Language: Objective C
Date: 104/12/07
Author: HappyMan
Blog: https://cg2010studio.wordpress.com/
*/
#pragma mark - 刪除 UserDefaults
NSUserDefaults *defs = [NSUserDefaults standardUserDefaults];
NSDictionary *dict = [defs dictionaryRepresentation];
for (id key in dict) {
[defs removeObjectForKey:key];
}
[defs synchronize];
清空前的User Defaults之key群：
(
GGUserDefaultsKeyLoginAccount,
AppleKeyboardsExpanded,
GGUserDefaultsKeyLoginPassword,
PCSavePendingUserDefaults,
GGUserDefaultsKeyhasFirstShowMenu,
GGUserDefaultsKeyIsLogin,
INNextHearbeatDate,
com.apple.content-rating.ExplicitBooksAllowed,
GGUserDefaultsKeyLoginPasswordAlternative,
AppleKeyboards,
HasUserRegisteredFonts,
PKEnableStockholmSettings,
GGUserDefaultsKeyRememberPassword,
AppleLanguagesDidMigrate,
com.apple.content-rating.TVShowRating,
com.apple.content-rating.ExplicitMusicPodcastsAllowed,
NSLanguages,
com.apple.content-rating.MovieRating,
GGUserDefaultsKeyQBId,
GGUserDefaultsKeyLoginAccountAlternative,
PreferredLanguages,
AddingEmojiKeybordHandled,
MSVLoggingMasterSwitchEnabledKey,
AppleLocale,
AppleLanguages,
NSInterfaceStyle,
com.apple.content-rating.AppRating,
AppleITunesStoreItemKinds
)
清空後的User Defaults之key群：
(
PKEnableStockholmSettings,
INNextHearbeatDate,
MSVLoggingMasterSwitchEnabledKey,
AppleITunesStoreItemKinds,
AddingEmojiKeybordHandled,
com.apple.content-rating.ExplicitBooksAllowed,
com.apple.content-rating.MovieRating,
HasUserRegisteredFonts,
AppleLanguagesDidMigrate,
com.apple.content-rating.AppRating,
AppleLanguages,
NSLanguages,
NSInterfaceStyle,
com.apple.content-rating.ExplicitMusicPodcastsAllowed,
AppleKeyboardsExpanded,
AppleKeyboards,
PreferredLanguages,
AppleLocale,
com.apple.content-rating.TVShowRating
)
key前綴為PC或GG，就是我在此專案中儲存資料用的key喔～
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