UDID被弃用，使用UUID来作为设备的唯一标识。获取到UUID后，如果用NSUserDefaults存储，当程序被卸载后重装时，再获得的UUID和之前就不同了。使用keychain存储可以保证程序卸载重装时，UUID不变。但当刷机或者升级系统后，UUID还是会改变的。但这仍是目前为止最佳的解决办法了，如果有更好的解决办法，欢迎留言。
#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. ");
}
[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。
NSString * uuid= [UUID getUUID];
NSLog(@"uuid=%@",uuid);