iOS開發——keychain的使用 唯一識別蘋果設備

通常情況下，我們用NSUserDefaults存儲數據信息，但是對於一些私密信息，比如密碼、證書等等，就需要使用更爲安全的keychain了。keychain裏保存的信息不會因App被刪除而丟失，在用戶重新安裝App後依然有效，數據還在。

使用蘋果官方發佈的KeychainItemWrapper或者SFHFKeychainUtils很方便，後來看到 iphone使用keychain來存取用戶名和密碼 一文，覺得對了解keychain有很大的幫助，於是ARC控也嘗試了一把。

需要導入Security.framework 

@implementation WQKeyChain  
+ (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];  
}  
  
+ (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);  
}  
  
+ (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;  
}  
  
+ (void)delete:(NSString *)service {  
    NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];  
    SecItemDelete((__bridge_retained CFDictionaryRef)keychainQuery);  
}  
@end  

比如，保存密碼
@interface WQUserDataManager : NSObject  
  
/** 
 *  @brief  存儲密碼 
 * 
 *  @param  password    密碼內容 
 */  
+(void)savePassWord:(NSString *)password;  
  
/** 
 *  @brief  讀取密碼 
 * 
 *  @return 密碼內容 
 */  
+(id)readPassWord;  
  
/** 
 *  @brief  刪除密碼數據 
 */  
+(void)deletePassWord;  
  
@end  

#import "WQUserDataManager.h"  

  
@implementation WQUserDataManager  
  
static NSString * const KEY_IN_KEYCHAIN = @"com.wuqian.app.allinfo";  
static NSString * const KEY_PASSWORD = @"com.wuqian.app.password";  
  
+(void)savePassWord:(NSString *)password  
{  
    NSMutableDictionary *usernamepasswordKVPairs = [NSMutableDictionary dictionary];  
    [usernamepasswordKVPairs setObject:password forKey:KEY_PASSWORD];  
    [WQKeyChain save:KEY_IN_KEYCHAIN data:usernamepasswordKVPairs];  
}  
  
+(id)readPassWord  
{  
    NSMutableDictionary *usernamepasswordKVPair = (NSMutableDictionary *)[WQKeyChain load:KEY_IN_KEYCHAIN];  
    return [usernamepasswordKVPair objectForKey:KEY_PASSWORD];  
}  
  
+(void)deletePassWord  
{  
    [WQKeyChain delete:KEY_IN_KEYCHAIN];  
}  
@end  

實現一個簡單的界面，把設定的密碼存起來，然後立即讀取顯示出來看看效果

-(IBAction)btnAciton:(id)sender  
{  
    [WQUserDataManager savePassWord:self.textfield.text];  
    self.label.text = [WQUserDataManager readPassWord];  
}  

達到了預期的效果。