原文地址

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface KeyChainManager : NSObject



/*!
 保存数据
 
 @data  要存储的数据
 @identifier 存储数据的标示
 */
+(BOOL) keyChainSaveData:(id)data withIdentifier:(NSString*)identifier ;

/*!
 读取数据
 
 @identifier 存储数据的标示
 */
+(id) keyChainReadData:(NSString*)identifier ;


/*!
 更新数据
 
 @data  要更新的数据
 @identifier 数据存储时的标示
 */
+(BOOL)keyChainUpdata:(id)data withIdentifier:(NSString*)identifier ;

/*!
 删除数据
 
 @identifier 数据存储时的标示
 */
+(void) keyChainDelete:(NSString*)identifier ;
@end

#import "KeyChainManager.h"

#import <Security/Security.h>


@implementation KeyChainManager
/*!
 创建生成保存数据查询条件
 */
+(NSMutableDictionary*) keyChainIdentifier:(NSString*)identifier {
    NSMutableDictionary * keyChainMutableDictionary = [NSMutableDictionary dictionaryWithObjectsAndKeys:(id)kSecClassGenericPassword,kSecClass,identifier,kSecAttrService,identifier,kSecAttrAccount,kSecAttrAccessibleAfterFirstUnlock,kSecAttrAccessible, nil];
    return keyChainMutableDictionary;
}

/*!
 保存数据
 */
+(BOOL) keyChainSaveData:(id)data withIdentifier:(NSString*)identifier{
    // 获取存储的数据的条件
    NSMutableDictionary * saveQueryMutableDictionary = [self keyChainIdentifier:identifier];
    // 删除旧的数据
    SecItemDelete((CFDictionaryRef)saveQueryMutableDictionary);
    // 设置新的数据
    [saveQueryMutableDictionary setObject:[NSKeyedArchiver archivedDataWithRootObject:data] forKey:(id)kSecValueData];
    // 添加数据
    OSStatus saveState = SecItemAdd((CFDictionaryRef)saveQueryMutableDictionary, nil);
    // 释放对象
    saveQueryMutableDictionary = nil ;
    // 判断是否存储成功
    if (saveState == errSecSuccess) {
        return YES;
    }
    return NO;
}


/*!
 读取数据
 */
+(id) keyChainReadData:(NSString*)identifier{
    id idObject = nil ;
    // 通过标记获取数据查询条件
    NSMutableDictionary * keyChainReadQueryMutableDictionary = [self keyChainIdentifier:identifier];
    // 这是获取数据的时，必须提供的两个属性
    // TODO: 查询结果返回到 kSecValueData
    [keyChainReadQueryMutableDictionary setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnData];
    // TODO: 只返回搜索到的第一条数据
    [keyChainReadQueryMutableDictionary setObject:(id)kSecMatchLimitOne forKey:(id)kSecMatchLimit];
    // 创建一个数据对象
    CFDataRef keyChainData = nil ;
    // 通过条件查询数据
    if (SecItemCopyMatching((CFDictionaryRef)keyChainReadQueryMutableDictionary , (CFTypeRef *)&keyChainData) == noErr){
        @try {
            idObject = [NSKeyedUnarchiver unarchiveObjectWithData:(__bridge NSData *)(keyChainData)];
        } @catch (NSException * exception){
            NSLog(@"Unarchive of search data where %@ failed of %@ ",identifier,exception);
        }
    }
    if (keyChainData) {
        CFRelease(keyChainData);
    }
    // 释放对象
    keyChainReadQueryMutableDictionary = nil;
    // 返回数据
    return idObject ;
}


/*!
 更新数据
 
 @data  要更新的数据
 @identifier 数据存储时的标示
 */
+(BOOL)keyChainUpdata:(id)data withIdentifier:(NSString*)identifier {
    // 通过标记获取数据更新的条件
    NSMutableDictionary * keyChainUpdataQueryMutableDictionary = [self keyChainIdentifier:identifier];
    // 创建更新数据字典
    NSMutableDictionary * updataMutableDictionary = [NSMutableDictionary dictionaryWithCapacity:0];
    // 存储数据
    [updataMutableDictionary setObject:[NSKeyedArchiver archivedDataWithRootObject:data] forKey:(id)kSecValueData];
    // 获取存储的状态
    OSStatus  updataStatus = SecItemUpdate((CFDictionaryRef)keyChainUpdataQueryMutableDictionary, (CFDictionaryRef)updataMutableDictionary);
    // 释放对象
    keyChainUpdataQueryMutableDictionary = nil;
    updataMutableDictionary = nil;
    // 判断是否更新成功
    if (updataStatus == errSecSuccess) {
        return  YES ;
    }
    return NO;
}


/*!
 删除数据
 */
+(void) keyChainDelete:(NSString*)identifier {
    // 获取删除数据的查询条件
    NSMutableDictionary * keyChainDeleteQueryMutableDictionary = [self keyChainIdentifier:identifier];
    // 删除指定条件的数据
    SecItemDelete((CFDictionaryRef)keyChainDeleteQueryMutableDictionary);
    // 释放内存
    keyChainDeleteQueryMutableDictionary = nil ;
}

@end

使用

    BOOL save = [KeyChainManager keyChainSaveData:@"思念诉说，眼神多像云朵" withIdentifier:Keychain];
    if (save) {
        NSLog(@"存储成功");
    }else {
        NSLog(@"存储失败");
    }
    // 获取数据
    NSString * readString = [KeyChainManager keyChainReadData:Keychain];
    NSLog(@"获取得到的数据:%@",readString);

    // 更新数据
    BOOL updata = [KeyChainManager keyChainUpdata:@"长发落寞，我期待的女孩" withIdentifier:Keychain];
    if (updata) {
        NSLog(@"更新成功");
    }else{
        NSLog(@"更新失败");
    }
    // 读取数据
    NSString * readUpdataString = [KeyChainManager keyChainReadData:Keychain];
    NSLog(@"获取更新后得到的数据:%@",readUpdataString);
    
    // 删除数据
    [KeyChainManager keyChainDelete:Keychain];
    // 读取数据
    NSString * readDeleteString = [KeyChainManager keyChainReadData:Keychain];
    NSLog(@"获取删除后得到的数据:%@",readDeleteString);