iphone密码储存

//获取密码
+ (NSString *) getPasswordForUsername: (NSString *) username andServiceName: (NSString *) serviceName error: (NSError **) error;

//保存密码
+ (void) storeUsername: (NSString *) username andPassword: (NSString *) password forServiceName: (NSString *) serviceName updateExisting: (BOOL) updateExisting error: (NSError **) error;

//删除密码
+ (void) deleteItemForUsername: (NSString *) username andServiceName: (NSString *) serviceName error: (NSError **) error;