1.添加 Security.framework
2.继承于NSObject .h

#import <Foundation/Foundation.h>
@interface KeyChain : NSObject
+ (NSMutableDictionary *)getKeychainQuery:(NSString *)service;
+ (void)save:(NSString *)service data:(id)data;
+ (id)load:(NSString *)service;
+ (void)delete:(NSString *)service;
@end

继承于NSObject .m

#import "KeyChain.h"
@implementation KeyChain
+ (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

3.UserDataManager.h

#import <Foundation/Foundation.h>
@interface UserDataManager : NSObject
/**
 *  @brief  存储密码
 *
 *  @param  password    密码内容
 */
+(void)savePassWord:(NSString *)password;
/**
 *  @brief  读取密码
 *
 *  @return 密码内容
 */
+(id)readPassWord;
/**
 *  @brief  删除密码数据
 */
+(void)deletePassWord;
@end

UserDataManager.m

#import "UserDataManager.h"
#import "KeyChain.h"

@implementation UserDataManager
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];
    [KeyChain save:KEY_IN_KEYCHAIN data:usernamepasswordKVPairs];
}
+(id)readPassWord
{
    NSMutableDictionary *usernamepasswordKVPair = (NSMutableDictionary *)[KeyChain load:KEY_IN_KEYCHAIN];
    return [usernamepasswordKVPair objectForKey:KEY_PASSWORD];
}
+(void)deletePassWord
{
    [KeyChain delete:KEY_IN_KEYCHAIN];
}
@end

4.ViewController

#import "ViewController.h"
#import "UserDataManager.h"
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UILabel *showLabel;
@end
@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];

    [UserDataManager savePassWord:@"123"];
}
- (IBAction)show:(UIButton *)sender {
    self.showLabel.text = [UserDataManager readPassWord];
}
@end