iOS开发：keychain存储UUID

通常情况下，我们用NSUserDefaults存储数据信息，但是对于一些私密信息，比如密码、证书等等，就需要使用更为安全的keychain了。keychain里保存的信息不会因App被删除而丢失，在用户重新安装App后依然有效，数据还在。

首先需要在TARGETS-Capabilities-Keychain sharing 中将开关打开，打开后会自动生成*.entitleements文件。

1、创建UUID类

UUID.h文件

#import <Foundation/Foundation.h>@interface UUID : NSObject+(NSString *)getUUID;@end

UUID.m文件

#import "UUID.h"#import "KeyChainStore.h"@implementation UUID+(NSString *)getUUID{    NSString * strUUID = (NSString *)[KeyChainStore load:KEY_USERNAME_PASSWORD];        //首次执行该方法时，uuid为空    if ([strUUID isEqualToString:@""] || !strUUID)    {        //生成一个uuid的方法        CFUUIDRef uuidRef = CFUUIDCreate(kCFAllocatorDefault);                strUUID = (NSString *)CFBridgingRelease(CFUUIDCreateString (kCFAllocatorDefault,uuidRef));                //将该uuid保存到keychain        [KeyChainStore save:KEY_USERNAME_PASSWORD data:strUUID];            }    return strUUID;}@end

2、创建KeyChainStore类

KeyChainStore.h文件

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

KeyChainStore.m文件

#import "KeyChainStore.h"@implementation KeyChainStore+ (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:(__bridge NSData *)keyData];        } @catch (NSException *e) {            NSLog(@"Unarchive of %@ failed: %@", service, e);        } @finally {        }    }    if (keyData)        CFRelease(keyData);    return ret;}+ (void)deleteKeyData:(NSString *)service {    NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];    SecItemDelete((CFDictionaryRef)keychainQuery);}@end

3、创建一个pch文件(不是必须);

pch文件的创建方法可参考：http://blog.csdn.net/huang2009303513/article/details/40375235

你有可能会在填Prefix Header 即pch文件的路径那里报错，最近又学习到一种更好的方式$(SRCROOT)/$(PROJECT_NAME)/PrefixHeader.pch,其中$(PROJECT_NAME)是相对工程名,比上面的方法更便捷.

#ifndef PrefixHeader_pch#define PrefixHeader_pch#define  KEY_USERNAME_PASSWORD @"com.company.app.usernamepassword"#define  KEY_USERNAME @"com.company.app.username"#define  KEY_PASSWORD @"com.company.app.password"#endif

4、使用

#import "ViewController.h"#import "UUID.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    NSString * uuid= [UUID getUUID];    NSLog(@"uuid=%@",uuid);    //第一次生成的uuid    //uuid=A9B9C149-03A9-472E-BF16-75386D491A08    //卸载之后生成的uuid（从钥匙串内取出的）    //uuid=A9B9C149-03A9-472E-BF16-75386D491A08    //重置系统之后生成的uuid(重新生成的)-若用户重置了系统的话uuid会重新生成就失去了唯一性。    //uuid=E83ACF06-D9E3-4EC0-A76D-1DE13E793813}