NSUserDefaults

新版本xocde，不可以获得设备的udid。以下是替待udid的方法：

 NSString* string    =   [[NSUserDefaults standardUserDefaults] stringForKey:@"deviceId"];
    if( [string isEqual:@""]|| string==nil )
    {
        CFUUIDRef deviceId = CFUUIDCreate (NULL);
        
        CFStringRef deviceIdStringRef = CFUUIDCreateString(NULL,deviceId);
        
        CFRelease(deviceId);
        
        NSString *deviceIdString = (NSString *)deviceIdStringRef;
        
        NSUserDefaults *standardUserDefault = [NSUserDefaults standardUserDefaults];
        
        [standardUserDefault setValue:deviceIdString forKey:@"deviceId"];
        
        [deviceIdString release];
        
        [standardUserDefault synchronize];
    }