使用keychain来存储，也就是钥匙串，使用keychain需要导入Security框架

自定义一个keychain的类

import <Security/Security.h>

@implementation CXDKeychain

• (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 {
  //获取搜索字典
  NSMutableDictionary *keychainQuery = [self getKeychainquery:service];
  //添加新的删除旧的
  SecItemDelete((__bridge_retained CFDictionaryRef)keychainQuery);
  //添加新的对象到字符串
  [keychainQuery setObject:[NSKeyedArchiver archivedDataWithRootObject:data] forKey:(__bridge_transfer id)kSecValueData];
  //查询钥匙串
  SecItemAdd((__bridge_retained CFDictionaryRef)keychainQuery, NULL);
  }

• (id)load:(NSString *)service {
  id ret = nil;
  NSMutableDictionary *keychainQuery = [self getKeychainquery:service];
  //配置搜索设置
  [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 *exception) {
  NSLog(@"Unarchive of %@ failed: %@", service, exception);
  } @finally {

    }
  

  }
  return ret;
  }

• (void)delete:(NSString *)service {
  NSMutableDictionary *keychainQuery = [self getKeychainquery:service];
  SecItemDelete((__bridge_retained CFDictionaryRef)keychainQuery);
  }

在别的类实现存储，加载，删除敏感信息方法
//用来标识这个钥匙串
static NSString const KEY_IN_KEYCHAIN = @"com.cxd.app.allinfo";
//用来标识密码
static NSString const KEY_PASSWORD = @"com.cxd.app.password";

• (void)savePassword:(NSString *)password {
  NSMutableDictionary *passwordDict = [NSMutableDictionary dictionary];
  [passwordDict setObject:password forKey:KEY_PASSWORD];
  [CXDKeychain save:KEY_IN_KEYCHAIN data:passwordDict];
  }

• (id)readPassword {
  NSMutableDictionary *passwordDict = (NSMutableDictionary *)[self load:KEY_IN_KEYCHAIN];
  return [passwordDict objectForKey:KEY_PASSWORD];
  }

• (void)deletePassword {
  [CXDKeychain delete:KEY_IN_KEYCHAIN];
  }