总结一下：
2.CFUUID、IDFA、IDFV都是可变的（其它方法，比如苹果自带的UUID和MAC地址基本上被禁止使用），但是IDFA和IDFV不一定都能获取到（iOS系统不同版本不一定支持），所以直接选择了CFUUID(iOS2.0就开始支持了)。
PS：
3.代码中使用stringByReplacingOccurrencesOfString将间隔符-去掉了（原来是这种：CAE1CC3A-92C1-45A5-9F55-932264020358，去掉后变为CAE1CC3A92C145A59F55932264020358）。
4.SdkMgr为自定义类名，根据需要自行修改。
NSString * const KEY_UDID_INSTEAD = @"com.app.uuid.test";
+(NSString *)getDeviceUUID{
NSString *getUDIDInKeychain = (NSString *)[SdkMgr load:KEY_UDID_INSTEAD];
if (!getUDIDInKeychain ||[getUDIDInKeychain isEqualToString:@""]||[getUDIDInKeychain isKindOfClass:[NSNull class]]) {
CFUUIDRef puuid = CFUUIDCreate( nil );
CFStringRef uuidString = CFUUIDCreateString( nil, puuid );
NSString * result = (NSString *)CFBridgingRelease(CFStringCreateCopy( NULL, uuidString));
CFRelease(puuid);
CFRelease(uuidString);
//去掉横线，保留32位长度
NSString *rst = [result stringByReplacingOccurrencesOfString:@"-" withString:@""];
[SdkMgr save:KEY_UDID_INSTEAD data:rst];
getUDIDInKeychain = (NSString *)[SdkMgr load:KEY_UDID_INSTEAD];
}
return getUDIDInKeychain;
}
#pragma mark - private
+ (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:(NSData *)keyData];
} @catch (NSException *e) {
NSLog(@"Unarchive of %@ failed: %@", service, e);
} @finally {
}
}
if (keyData)
CFRelease(keyData);
return ret;
}
+ (void)delete:(NSString *)service {
NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];
SecItemDelete((CFDictionaryRef)keychainQuery);
}
@end
