(绝对有用)iOS获取UUID，并使用keychain存储

#import 尖括号（Foundation/Foundation.h）

@interface UUID : NSObject

+(NSString *)getUUID;

@end

#import "UUID.h"

#import 尖括号（Foundation/Foundation.h）

#import "KeychainItemWrapper.h"

@implementation UUID

+(NSString *)getUUID

{

    KeychainItemWrapper *keychainItem = [[KeychainItemWrapper alloc]

                                    initWithIdentifier:@"UUID"

                                                                                 accessGroup:@"YOUR_BUNDLE_SEED.com.yourcompany.userinfo"];

    NSString *strUUID = [keychainItem objectForKey:(id)CFBridgingRelease(kSecValueData)];

    //首次执行该方法时，uuid为空

    if ([strUUID isEqualToString:@""])

    {

        CFUUIDRef uuidRef = CFUUIDCreate(kCFAllocatorDefault);

        strUUID = (NSString *)CFBridgingRelease(CFUUIDCreateString(kCFAllocatorDefault,uuidRef));

        [keychainItem setObject:strUUID forKey:(id)CFBridgingRelease(kSecValueData)];

    }

    return strUUID;

}

@end

第二个类是苹果官方的一个Demo里封装的,Demo的下载地址：http://developer.apple.com/library/ios/#samplecode/GenericKeychain/Listings/Classes_KeychainItemWrapper_h.html#//apple_ref/doc/uid/DTS40007797-Classes_KeychainItemWrapper_h-DontLinkElementID_9

KeychainItemWrapper.h中的代码：

#import 尖括号（UIKit/UIKit.h）

@interface KeychainItemWrapper : NSObject

{

    NSMutableDictionary *keychainItemData;

    NSMutableDictionary *genericPasswordQuery;

}

@property (nonatomic, retain) NSMutableDictionary *keychainItemData;

@property (nonatomic, retain) NSMutableDictionary *genericPasswordQuery;

- (id)initWithIdentifier: (NSString *)identifier accessGroup:(NSString *) accessGroup;

- (void)setObject:(id)inObject forKey:(id)key;

- (id)objectForKey:(id)key;

- (void)resetKeychainItem;

@end

KeychainItemWrapper.m中的代码：

#import "KeychainItemWrapper.h"

#import 尖括号(Security/Security.h)

@interface KeychainItemWrapper (PrivateMethods)

- (NSMutableDictionary *)secItemFormatToDictionary:(NSDictionary *)dictionaryToConvert;

- (NSMutableDictionary *)dictionaryToSecItemFormat:(NSDictionary *)dictionaryToConvert;

- (void)writeToKeychain;

@end

@implementation KeychainItemWrapper

@synthesize keychainItemData, genericPasswordQuery;

- (id)initWithIdentifier: (NSString *)identifier accessGroup:(NSString *) accessGroup;

{

    if (self = [super init])

    {

         genericPasswordQuery = [[NSMutableDictionary alloc] init];

[genericPasswordQuery setObject:(id)CFBridgingRelease(kSecClassGenericPassword) forKey:(id)kSecClass];

        [genericPasswordQuery setObject:identifier forKey:(id)CFBridgingRelease(kSecAttrGeneric)];

if (accessGroup != nil)

{

#if TARGET_IPHONE_SIMULATOR

#else

[genericPasswordQuery setObject:accessGroup forKey:(id)kSecAttrAccessGroup];

#endif

}

        [genericPasswordQuery setObject:(id)CFBridgingRelease(kSecMatchLimitOne) forKey:(id)kSecMatchLimit];

        [genericPasswordQuery setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnAttributes];

        NSDictionary *tempQuery = [NSDictionary dictionaryWithDictionary:genericPasswordQuery];

        NSMutableDictionary *outDictionary = nil;

        if (! SecItemCopyMatching((CFDictionaryRef)tempQuery, (CFTypeRef*)&outDictionary) == noErr)

        {

            [self resetKeychainItem];

[keychainItemData setObject:identifier forKey:(id)kSecAttrGeneric];

if (accessGroup != nil)

{

#if TARGET_IPHONE_SIMULATOR

#else

[keychainItemData setObject:accessGroup forKey:(id)kSecAttrAccessGroup];

#endif

}

}

        else

        {

            self.keychainItemData = [self secItemFormatToDictionary:outDictionary];

        }

[outDictionary release];

    }

return self;

}

- (void)dealloc

{

    [keychainItemData release];

    [genericPasswordQuery release];

[super dealloc];

}

- (void)setObject:(id)inObject forKey:(id)key 

{

    if (inObject == nil) return;

    id currentObject = [keychainItemData objectForKey:key];

    if (![currentObject isEqual:inObject])

    {

        [keychainItemData setObject:inObject forKey:key];

        [self writeToKeychain];

    }

}

- (id)objectForKey:(id)key

{

    return [keychainItemData objectForKey:key];

}

- (void)resetKeychainItem

{

OSStatus junk = noErr;

    if (!keychainItemData) 

    {

        self.keychainItemData = [[NSMutableDictionary alloc] init];

    }

    else if (keychainItemData)

    {

        NSMutableDictionary *tempDictionary = [self dictionaryToSecItemFormat:keychainItemData];

junk = SecItemDelete((CFDictionaryRef)tempDictionary);

        NSAssert( junk == noErr || junk == errSecItemNotFound, @"Problem deleting current dictionary." );

    }

    [keychainItemData setObject:@"" forKey:(id)kSecAttrAccount];

    [keychainItemData setObject:@"" forKey:(id)kSecAttrLabel];

    [keychainItemData setObject:@"" forKey:(id)kSecAttrDescription]; 

  [keychainItemData setObject:@"" forKey:(id)kSecValueData];

}

- (NSMutableDictionary *)dictionaryToSecItemFormat:(NSDictionary *)dictionaryToConvert

{

   NSMutableDictionary *returnDictionary = [NSMutableDictionary dictionaryWithDictionary:dictionaryToConvert];

    [returnDictionary setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];

  NSString *passwordString = [dictionaryToConvert objectForKey:(id)kSecValueData];

    [returnDictionary setObject:[passwordString dataUsingEncoding:NSUTF8StringEncoding]forKey:(id)kSecValueData];

    return returnDictionary;

}

- (NSMutableDictionary *)secItemFormatToDictionary:(NSDictionary *)dictionaryToConvert

{

    NSMutableDictionary *returnDictionary = [NSMutableDictionarydictionaryWithDictionary:dictionaryToConvert];

    [returnDictionary setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnData];

         [returnDictionary setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];

     NSData *passwordData = NULL;

    if (SecItemCopyMatching((CFDictionaryRef)returnDictionary, (CFTypeRef*)&passwordData) == noErr)

    {

        [returnDictionary removeObjectForKey:(id)kSecReturnData];

        NSString *password = [[[NSString alloc] initWithBytes:[passwordData bytes]length:[passwordData length] 

                                                     encoding:NSUTF8StringEncoding]autorelease];

        [returnDictionary setObject:password forKey:(id)kSecValueData];

    }

    else

    {

           NSAssert(NO, @"Serious error, no matching item found in the keychain.\n");

    }

    [passwordData release];

return returnDictionary;

}

- (void)writeToKeychain

{

    NSDictionary *attributes = NULL;

    NSMutableDictionary *updateItem = NULL;

OSStatus result;

    if (SecItemCopyMatching((CFDictionaryRef)genericPasswordQuery, (CFTypeRef*)&attributes) == noErr)

    {

        updateItem = [NSMutableDictionary dictionaryWithDictionary:attributes];

        [updateItem setObject:[genericPasswordQuery objectForKey:(id)kSecClass] forKey:(id)kSecClass];

        NSMutableDictionary *tempCheck = [self dictionaryToSecItemFormat:keychainItemData];

        [tempCheck removeObjectForKey:(id)kSecClass];

#if TARGET_IPHONE_SIMULATOR

[tempCheck removeObjectForKey:(id)kSecAttrAccessGroup];

#endif

        result = SecItemUpdate((CFDictionaryRef)updateItem, (CFDictionaryRef)tempCheck);

NSAssert( result == noErr, @"Couldn‘t update the Keychain Item." );

    }

    else

    {

        result = SecItemAdd((CFDictionaryRef)[self dictionaryToSecItemFormat:keychainItemData], NULL);

NSAssert( result == noErr, @"Couldn‘t add the Keychain Item." );

    }

}

@end

                                         initWithIdentifier:@"UUID"

                                        accessGroup:@"YOUR_BUNDLE_SEED.com.yourcompany.userinfo"];

    （1）在项目相同的目录下创建KeychainAccessGroups.plist文件。