相信在我們存儲(chǔ)一些數(shù)據(jù)的時(shí)候都會(huì)遇到一些苦惱逻谦，如果應(yīng)用一旦被用戶刪除咸产，那么設(shè)備中的信息就會(huì)被清除掉。此時(shí)慎陵，keychain就發(fā)揮了作用眼虱，當(dāng)應(yīng)用被用戶刪除掉時(shí)，保存在keychain中的數(shù)據(jù)還會(huì)存在席纽，除非用戶重裝系統(tǒng)捏悬。那么我們就簡(jiǎn)單說明下keychain的使用吧江醇！
一硼啤、以保存密碼為例：
+ (NSMutableDictionary *)getKeychainQuery:(NSString *)service {
return [NSMutableDictionary dictionaryWithObjectsAndKeys:
(__bridge_transfer id)kSecClassGenericPassword,(__bridge_transfer id)kSecClass,
service, (__bridge_transfer id)kSecAttrService,
service, (__bridge_transfer id)kSecAttrAccount,
(__bridge_transfer id)kSecAttrAccessibleAfterFirstUnlock,(__bridge_transfer id)kSecAttrAccessible,
nil];
}
1.保存數(shù)據(jù)：
+ (void)save:(NSString *)service data:(id)data {
//Get search dictionary
NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];
//Delete old item before add new item
SecItemDelete((__bridge_retained CFDictionaryRef)keychainQuery);
//Add new object to search dictionary(Attention:the data format)
[keychainQuery setObject:[NSKeyedArchiver archivedDataWithRootObject:data] forKey:(__bridge_transfer id)kSecValueData];
//Add item to keychain with the search dictionary
SecItemAdd((__bridge_retained CFDictionaryRef)keychainQuery, NULL);
NSLog(@"save url to keychain");
}
2.取數(shù)據(jù)：
+ (id)load:(NSString *)service {
id ret = nil;
NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];
//Configure the search setting
[keychainQuery setObject:(id)kCFBooleanTrue forKey:(__bridge_transfer id)kSecReturnData];
[keychainQuery setObject:(__bridge_transfer id)kSecMatchLimitOne forKey:(__bridge_transfer id)kSecMatchLimit];
CFDataRef keyData = NULL;
if (SecItemCopyMatching((__bridge_retained CFDictionaryRef)keychainQuery, (CFTypeRef *)&keyData) == noErr) {
@try {
ret = [NSKeyedUnarchiver unarchiveObjectWithData:(__bridge_transfer NSData *)keyData];
} @catch (NSException *e) {
NSLog(@"Unarchive of %@ failed: %@", service, e);
} @finally {
}
}
return ret;
}
3.刪除數(shù)據(jù)：
+ (void)delete:(NSString *)service {
NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];
SecItemDelete((__bridge_retained CFDictionaryRef)keychainQuery);
}
二、在控制器中使用（我把上面的方法封裝在了YNKeyChain這個(gè)類里面方便使用）：
static NSString * const KEY_PASSWORD = @"ynwang.app.password";
//保存
- (IBAction)saveAction:(id)sender {
NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];
[dictionary setObject:self.passwordTextField.text forKey:KEY_PASSWORD];
[YNKeyChain save:KEY_PASSWORD data:dictionary];
}
//刪除
- (IBAction)deleteAction:(id)sender {
[YNKeyChain delete:KEY_PASSWORD];
}
//取數(shù)據(jù)
- (IBAction)showPasswordAction:(id)sender {
NSDictionary *dic = [YNKeyChain load:KEY_PASSWORD];
if (dic) {
self.passwordLabel.text = dic[KEY_PASSWORD];
}
else{
self.passwordLabel.text = @"空";
}
}
三粪薛、運(yùn)行結(jié)果：
四纺铭、keychain的另一個(gè)重要的作用寇钉，就是可以共享同一個(gè)開發(fā)者賬號(hào)的不同APP之間的信息，這樣就實(shí)現(xiàn)了兩個(gè)不同應(yīng)用之間信息的共享舶赔。主要有兩個(gè)步驟扫倡。
1.在APP target的bulib Setting里面添加Code Signing Entitlements為包含AceessGroup的分組信息的plist文件，否則會(huì)出現(xiàn)找不到文件的錯(cuò)誤竟纳。如下圖：
2.新建一個(gè)名字為Code Signing Entitlements中的plist文件撵溃，注意該文件的結(jié)構(gòu)中最頂層的節(jié)點(diǎn)必須是一個(gè)名為“keychain-access-groups”的Array，并且該Array中每一項(xiàng)都是一個(gè)描述分組的NSString锥累。對(duì)于String的格式也有相應(yīng)要求缘挑，格式為:"AppIdentifier.com.*"，其中AppIdentifier就是你的開發(fā)者帳號(hào)對(duì)應(yīng)的ID桶略。
原文鏈接：http://www.reibang.com/p/ec8cab4bc0a4著作權(quán)歸作者所有语淘，轉(zhuǎn)載請(qǐng)聯(lián)系作者獲得授權(quán)鬼悠，并標(biāo)注“簡(jiǎn)書作者”。
以上為keychain的簡(jiǎn)單使用亏娜，感謝會(huì)飛的咸魚提供的文章參考。后續(xù)會(huì)繼續(xù)更新蹬挺，希望對(duì)大家有用维贺。
