I have the paid content on my application on App Store. And I save it using the following code:
paidContentCount = [[NSUserDefaults standardUserDefaults] integerForKey:#"paidContentCount"];
But it's easy to hack it. How can I protect integer data from hacking?
Never store such settings in NSUserDefaults! Use an iOS Keychain for it. Here is the wrapper, which makes the biggest part of work.
Besides it, you can read this article from Ray Wenderlich - there are a lot of good ideas of basic security.
You can try saving your content as string with [NSString hash] method, and after your app is loaded, compare paid content's hashes with value from NSUserDefaults
UPDATE: forgot that [NSString hash] returns NSInteger
Related
Just wondering if anybody experience this issue?
I am developing an application in iOS using Objective-C at the moment.
Sometimes my data in NSUserDefaults will be missing after I compile the app.
But if I ignore it and recompile the app again the data suddenly reappears.
I already synchronized in several places (not in every key, but only in several places).
If anyone happened to face this issue before I hope you can share how to handle this issue.
P.S. I need a storage to save 1 particular object so I can retrieve it when the app reopens.
Edited to add the code
NSString *enPIN = [[NSString alloc]initWithString:[NSString stringWithFormat:#"%#", [enterField.text md5]]];
[[NSUserDefaults standardUserDefaults] setObject:enPIN forKey:#"pin"];
[[NSUserDefaults standardUserDefaults]synchronize];
NSLog(#"check pin %#", [[NSUserDefaults standardUserDefaults] objectForKey:#"pin"]);
The object is a string, i hash it using md5 and then store it in nsuserdefault, if it only randomly dissapearing maybe its not weird, but its also reapearing again after it dissapear if i recompile the apps
Check if your defaults are using only string value or bool or such.
If you are using any Object with Class (key and parameters) like NSObject to store in defaults I prefer you do the encoding and decoding accordingly before storing and retrieving the values.
Also If you storing any NSDictionary check if any of the object value inside that dictionary is not anything other than Bool, String , if there also any NSObject class or reference is stored then you may face same issue.
Refer this stackoverflow link as to how encode objects before storing to NSUserDefaults.
Lastly [defaults synchronise] call mandatory on viewwilldisappear or immediately after storing new value whichever way is your implementation.
Hope this helps.
I had a similar issue the other day with NSUserDefaults
Not quite sure what was causing it, but it was due to a bug in Xcode. I was able to fix the issue without changing my code at all. I simply cleaned the project (CMD-Shift-K) and restarted my computer, and then it worked just fine. It's worth a try
Are you getting any kind of error messages in the console?
Hello I can not save locally where I have to save an array of strings, I add that this array must be saved when closing the application for iOS and the reopening needs to be recharged, I found thousands of guides online but none are very specific, someone says use NSUserDefaults others say to use NSCoding but in both cases i can not recharge these data can anyone help me?
To Save SMALL data - NSUserDefaults, NSCoding as suggested by other people or saving in plist also or else create a file in document directory and write the contents of array in that file.
LARGE Data- Save it in database using either sqlite or core data.
Choice depends on the requirement of the application and since you have not given the details of the data like maximum number of strings in the array, everyone can suggest you instead of telling a solution. Hope it helps :)
You can use NSUserDefaults:
[[NSUserDefaults standardUserDefaults] setObject:yourMutableArray forKey:#"Key"];
To get the value from NSMutableArray:
NSMutableArray *array = [NSMutableArray arrayWithArray:[[NSUserDefaults standardUserDefaults] objectForKey:#"Key"]];
Hope this is helpful.
I've got a pretty simple task that I'm trying to accomplish in Objective-C.
I make a call to a web site, and get a value from the web site through an HTTP call. I want to save this value to disk so I can retrieve it later.
What would be the best method to do this - a text file, or in the PList file?
It's just one value that may occasionally be updated. The call to the web site is made on-demand.
Consider using NSUserDefaults for storing single values
For Storing:
[[NSUserDefaults standardUserDefaults] setInteger:100 forKey:#"storageKey"];
For Retrieving:
NSInteger myValue = [[NSUserDefaults standardUserDefaults] integerForKey:storageKey];
What kind of database do you suggest? I want to store user email, username, password, and a couple other random pieces of information. It doesn't have to be fancy. Just a simple database. Are there any free options?
The user information needs to be stored in the keychain to keep it secure.
Any other information could be stored in any one of:
User defaults NSUserDefaults
File on disk (maybe a plist)
Database Core Data (technically just a file on disk)
Which you choose depends on what the data is, how much there is and what kind of access you need to it.
If your data is small and chosen by the user as some kind of setting then user defaults makes sense and is the lowest cost for you to implement.
To use a database, check out Core Data intro.
Wain is right but I think as you want to store small amount of data for further use, the most efficient ways is to use NSUserDefault.
NSUserDefault stores data in NSDictionary type things.
I think this is the step you have to take:
1- check if data exists. I mean if user selected the number if the last run of your app. So in viewDidLoad method:
NSMutableDictionary *userDefaultDataDictionary = [[[NSUserDefaults standardUserDefaults] dictionaryForKey:ALL_DATA_KEY] mutableCopy];
if (userDefaultDataDictionary) {
// so the dictionary exists, which means user has entered the number in previous app run
// and you can read it from the NSDictionaty:
if(userDefaultDataDictionary[LABLE_KEY]){
//and store it
}
}
2 - you can implement some method like syncronize to store data in NSUserDefault every time something has been changed.
- (void) synchronize
{
NSMutableDictionary *dictionaryForUserDefault = [[[NSUserDefaults standardUserDefaults] dictionaryForKey:ALL_DATA_KEY] mutableCopy];
if(!dictionaryForUserDefault)
dictionaryForUserDefault = [[NSMutableDictionary alloc] init];
dictionaryForUserDefault[LABLE_KEY] = //data you want to store
[[NSUserDefaults standardUserDefaults] setObject:dictionaryForUserDefault forKey:ALL_DATA_KEY];
[[NSUserDefaults standardUserDefaults] synchronize];
}
P.S. and don't forget to #define your keys for your dictionary:
#define LABLE_KEY #"Lables"
#define ALL_DATA_KEY #"AllData"
Store it in a plist. If you're talking about data pertaining to one or a few users, that's probably the easy thing. here is a simple example.
Since you say database, store in Sqlite. There's some provided stuff for it already in xcode.
The entire database is contained in one file, which can be moved around if you need to.
Here is some more information on how to use one in your app.
I was wondering if there is a way to store small amounts of data, without going to a full-blown core-data API. I just need to store 6 'double' values somewhere... What's the best approach for that?
Thanks, Alex.
Core Data is just one way to store data, and it only makes sense when you need the things that it does. Here are five good options for storing your data:
Use NSUserDefaults. (Dead simple.)
Store the data in an appropriate structure (say, NSDictionary) and store it as a property list. (Pretty darn easy.)
Store the data in a class of your own design that implements NSCoding, and then write an instance of that class to a file using NSKeyedArchiver. (Works well for storing entire object graphs; this is basically what IB does. It might take an hour or two for the light to come on, but once you understand it this is a very nice way to read and write objects.)
Use Cocoa Touch's file system API, notably NSFileHandle and NSFileManager. (Conceptually simple if you've ever worked with a file system before. Puts you in complete control.)
Use the regular old POSIX file system API. (Best for existing Unix code, or code that you also want to compile on other platforms.)
Before you jump into any of those, read Apple's Archives and Serializations Programming Guide, User Defaults Programming Topics, and File System Programming Guide.
You can use NSUserDefaults to accomplish that (http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSUserDefaults_Class/Reference/Reference.html).
-(void)saveToUserDefaults:(NSString*)myString
{
NSUserDefaults *standardUserDefaults = [NSUserDefaults standardUserDefaults];
if (standardUserDefaults) {
[standardUserDefaults setObject:myString forKey:#"Prefs"];
[standardUserDefaults synchronize];
}
}
-(NSString*)retrieveFromUserDefaults
{
NSUserDefaults *standardUserDefaults = [NSUserDefaults standardUserDefaults];
NSString *val = nil;
if (standardUserDefaults)
val = [standardUserDefaults objectForKey:#"Prefs"];
return val;
}
The easiest way to store small amounts of data without using some of the larger API's is the NSUserDefaults class. It's really easy to set up and use.