iphone使用keychain来存取用户名和密码

转载地址：http://hi.baidu.com/givingmore/item/39d0653f54df67ae124b1475

iOS的keychain服务提供了一种安全的保存私密信息（密码，序列号，证书等）的方式。每个ios程序都有一个独立的keychain存储。从ios 3.0开始，跨程序分享keychain变得可行。

 

下面就使用keychain来实现存取用户名和密码。

 

苹果已经有现成的类封装好了keychain,KeychainItemWrapper.h和KeychainItemWrapper.m文件,可以在GenericKeychain实例里找到。

 

但是这里我只需要存取用户名和密码，就不用苹果提供的类了，自己写个简单的类来实现就好。

 

代码如下：

 

CHKeychain.h  [cpp] view plaincopy#import <Foundation/Foundation.h>  #import <Security/Security.h>      @interface CHKeychain : NSObject    + (void)save:(NSString *)service data:(id)data;  + (id)load:(NSString *)service;  + (void)delete:(NSString *)service;      @end    CHKeychain.m  [cpp] view plaincopy#import "CHKeychain.h"    @implementation CHKeychain  + (NSMutableDictionary *)getKeychainQuery:(NSString *)service {      return [NSMutableDictionary dictionaryWithObjectsAndKeys:              (id)kSecClassGenericPassword,(id)kSecClass,              service, (id)kSecAttrService,              service, (id)kSecAttrAccount,              (id)kSecAttrAccessibleAfterFirstUnlock,(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((CFDictionaryRef)keychainQuery);      //Add new object to search dictionary(Attention:the data format)      [keychainQuery setObject:[NSKeyedArchiver archivedDataWithRootObject:data] forKey:(id)kSecValueData];      //Add item to keychain with the search dictionary      SecItemAdd((CFDictionaryRef)keychainQuery, NULL);  }    + (id)load:(NSString *)service {      id ret = nil;      NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];      //Configure the search setting      //Since in our simple case we are expecting only a single attribute to be returned (the password) we can set the attribute kSecReturnData to kCFBooleanTrue      [keychainQuery setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnData];      [keychainQuery setObject:(id)kSecMatchLimitOne forKey:(id)kSecMatchLimit];      CFDataRef keyData = NULL;      if (SecItemCopyMatching((CFDictionaryRef)keychainQuery, (CFTypeRef *)&keyData) == noErr) {          @try {              ret = [NSKeyedUnarchiver unarchiveObjectWithData:(NSData *)keyData];          } @catch (NSException *e) {              NSLog(@"Unarchive of %@ failed: %@", service, e);          } @finally {  }      }      if (keyData)       CFRelease(keyData);      return ret;  }    + (void)delete:(NSString *)service {      NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];      SecItemDelete((CFDictionaryRef)keychainQuery);  }      @end  

首先需要定义几个字符串用来做key：

NSString * const KEY_USERNAME_PASSWORD = @"com.company.app.usernamepassword";  NSString * const KEY_USERNAME = @"com.company.app.username";  NSString * const KEY_PASSWORD = @"com.company.app.password";  

把用户名和密码存入keychain：

NSMutableDictionary *usernamepasswordKVPairs = [NSMutableDictionary dictionary];  [usernamepasswordKVPairs setObject:txtfldUsername.text forKey:KEY_USERNAME];  [usernamepasswordKVPairs setObject:txtfldPassword.text forKey:KEY_PASSWORD];  [CHKeychain save:KEY_USERNAME_PASSWORD data:usernamepasswordKVPairs];  

从keychain中取出用户名和密码：

NSMutableDictionary *usernamepasswordKVPairs = (NSMutableDictionary *)[CHKeychain load:KEY_USERNAME_PASSWORD];  txtfldUsername.text = [usernamepasswordKVPairs objectForKey:KEY_USERNAME];  txtfldPassword.text = [usernamepasswordKVPairs objectForKey:KEY_PASSWORD];  

删除一个keychain item:

[CHKeychain delete:KEY_USERNAME_PASSWORD];  

另外附上一篇写得更详细的e文：http://useyourloaf.com/blog/2010/3/29/simple-iphone-keychain-access.html