Is there any way to save data without connecting to server on the iPhone? If so, please describe how.
Look at the NSUserDefaults class. It can save primitives and NSArray objects of primitives.
Example, your app might write out before app terminates in your app delegate:
[[NSUserDefaults standardUserDefaults] setString:#"Value" forKey:#"Key"];
And then read it in after launch:
NSString *dataYouNeed = [[NSUserDefaults standardUserDefaults] stringForKey:#"Key"];
Just remember to handle the nil case gracefully (i.e. that the app will keep working immediately after a fresh install or a reset to the user defaults).
Edit: the question has already been more-or-less rewritten. Obviously if you need to store data that will act as your application's model (in the MVC sense), Core Data or sqlite is where you would do best to start looking.
If it's a small number of things, use NSUserDefaults. If it's a lot of stuff, use Core Data.
Related
I am developing one application. In my application I want to develop log in page using a plist.
My requirement is when user enters username and password they go to next view.
How do I create a log in page?
I am new to the programming. Please send me any tutorial or sample code.
Thanks in advance
I don't know why you are try to use plist for that. You can (and should) use NSUserDefaults (this is also plist but easy to manage).
Try to save data:
[[NSUserDefaults standardUserDefaults] setObject:#"myName" forKey:#"userName"];
and later get:
[[NSUserDefaults standardUserDefaults] stringForKey:#"userName"];
Of course i probably don't have to tell you that storing password in plain text is a very bad idea in general.
as I get closer to releasing my app, I'm trying to make sure that I'm using stable code to check if the app has been launched before (in order to perform some first time setup). Is this (obviously a no frills method that doesn't take into account app version and updates) pretty much a rock solid way to determine if the app has been launched?
In my app delegate didFinishLaunchingWithOptions method, I perform the following each time:
NSUserDefaults *defaults =[NSUserDefaults standardUserDefaults];
if(![defaults objectForKey:#"not_first_launch"])
{
NSLog(#"This is the first time the app has been launched.\nPerforming first-time setup procedures...");
[self runFirstTimeSetup];
}
My second question is basically, can I assume that when I release an app update, that the user's documents directory for my specific app's sandbox will be left unerased? Does an app update simply add to the directory, not wipe it clean and re-install? I need the user's files to stick around even when I update the app (pretty obvious) but I don't want to make the wrong assumption and have users lose data every time I release an update.
Thanks!
Yes, that's a good use of NSUserDefaults.
User data is preserved through updates.
Just make sure you keep the data that comes with your app and the data generated during runs in separate bins. So that if you have to change the former (via an app update), the latter remains untouched. For example, don't put both of them in the same SQLite table.
I know you already accepted an answer, but I just wanted to touch on the subject. The way I check if the app is being launched for the first time is like this:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
...normal code...
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
if (![defaults objectForKey:#"kFirstUse"]) {
[defaults setObject:[NSDate date] forKey:#"kFirstUse"];
[defaults synchronize];
}
}
The reason why I wanted to post is because while I check if this is the user's first launch, I also save the date of their first launch. For no extra code, I figured why not save this first launch date. I don't use that info at all in my app, but I was thinking maybe in the future I might. In the future, I was thinking about adding in App Purchase, and I would give the stuff away for free to my initial users; so this allows me to be prepared for the future and accomplish my goal at the same time.
And just for completeness, NSUserDefaults do persist between app updates, just make sure not to change the key to any object, otherwise that object won't be found.
Another good thing to add is that line [defaults synchronize]; - that literally makes the app save that data. The app periodically automatically saves the data, but I like to be safe and know that my stuff is saved.
let me know if you have any other questions
In my iPhone app the user can choose from a large list of audio on demand programs available on a website, sorted by speakers, programs names and days of the week.
I'd like the app to have a history of the most recent heard programs, so the user can keep track of what he has already listened to, including the date and time of accesses.
When the user is in the final stage of his choices I have three resulting NSStrings available in memory:
NSString *program;
NSString *speakerName;
NSString *weekDay;
How can I build a database, a history access, storing these 3 strings (plus date, time and how many minutes the audio has been played) every time the user listens to a different audio file so he can have a list of his played programs?
I'm reading about SQLite and Core Data for the iPhone but I'm not certain if that's the way to go, since I'll have just a few elements to save each time on a database.
Does anyone know of a sample xCode project for doing that? What should I study to accomplish this task?
Any suggestions/guidelines will be greatly appreciated. Thanks!
For something this simple, you should use NSUserDefaults.
Basically, NSUserDefaults gives you a dictionary into which you can put NSStrings, NSDates, NSNumbers, or NSDictionarys or NSArrays of these objects. To use it you do something like
[[NSUserDefaults standardUserDefaults] setValue:myString forKey:#"myKey"];
Then later, you can access the value by doing:
[[NSUserDefaults standardUserDefaults] valueForKey:#"myKey"];
Don't worry, I'm not trying to hack someone else's app, if that's what you're thinking =).
I want to have 2 versions of my app, a free version and a deluxe version. My plan was to use an in-app purchase to enable the deluxe version by setting a boolean value in the plist file.
My question is: is this secure or is it easily circumvented? And if it is not secure, can someone suggest a simple alternative? I don't want to download additional content, I would rather keep all of the functionality within the app and enable it somehow.
Edit: I don't mean the application plist file, but something like the user defaults file.
You should store this in the keychain, this is what I'll do. The keychain is far more secure than a .plist or the user defaults (which are .plists, too, as far as I know). Have a look at SFHFKeychainUtils, you should be able to use this or just implement a better method exactly for the need to save a simple bool.
It is easy to edit the com.something.plist without jailbreaking. With a free tool* you can browse your device, you can also edit and save these files. If you store your inapp purchase something like this:
[[NSUserDefaults standardUserDefaults] setBool:YES forKey:#"com.example.pack1"];
[[NSUserDefaults standardUserDefaults] synchronize];
then this will be written to the plist:
<key>com.example.pack1</key>
<true/>
If you name your packages like this: pack1, pack2 etc., and somebody edits your plist (copy/pasting the first key), he/she could use the locked feature easily.
A not too hard to implement method would be to save like this:
[[NSUserDefaults standardUserDefaults] setValue:[self sha1ValueForKey:#"com.example.pack1"]
forKey:#"com.example.pack1"];
[[NSUserDefaults standardUserDefaults] synchronize];
where -sha1ValueForKey: is
-(NSString *)sha1ValueForKey:(NSString *)key {
return [self sha1:[NSString stringWithFormat:#"<SALT>%#", key]];
}
You have to change <SALT> to something.
You can find -sha1: here: http://www.makebetterthings.com/iphone/how-to-get-md5-and-sha1-in-objective-c-ios-sdk/
After this you can verify if the key matches the hashed value.
If somebody wants to hack your plist he/she has to know your hashing mechanism and salt.
This is not the safest way to protect your application but it is easy to implement.
*iExplorer
EDIT:
The suggested method only protects - somewhat - your IAP if the user doesn't have access to the hashed value. If someone gets it from somewhere, it is easy to copy that data to the plist. If the SALT is device dependent copying is useless.
I would recommend reading up on verifying in-app purchases. It sounds to me like you are trying to roll your own in-app purchase verification system which may be wrought with issues you might not have thought of yet. You have to be careful with your user's purchases that they will behave the same in your application as they will in any other, lest ye lose their trust (and future sales!)
Instead of worrying about the Info.plist file, why not just set a preference? Somewhere in your code, this would give you your boolean value:
[[NSUserDefaults standardUserDefaults] boolForKey:#"someKey"];
If the value doesn't exist, the result will be nil. This code sets the value:
[[NSUserDefaults standardUserDefaults] setBool:YES forKey:#"someKey"];
Plus, these values will be backed up in iTunes, so if the user moves their backup to a new iPhone or simply restores from backup, the values will be restored.
I don't have an answer, but it seems that editing your plist file dynamically is not possible, if I trust this subject :
You can not edit you're info.plist
file dynamically. When you submit your
app to The App Store, your app bundle,
which includes info.plist, can't
change because the signature created
when you compile you app is based on
the bundle.
Any pirate has a jail-broken iPhone
Any jail-broken device offers full file system access via tools like PhoneDisk, etc
Any file system access allows people to change the values in your applications .plist file
Game over.
Now, its not trivial to wrapper that up for the script kiddies but then again its not that hard either.
Storing state in defaults is no more nor less safe from privacy than having two versions of your app. Pirates will either pirate the deluxe version, or they'll pirate the unified version with the flag set.
I've started a new iPhone app that needs to remember a single, 40-char string. That's it. I've hooked into Core Data, and am reading about it now, but it really seems like overkill. Is there an easier way to do something so simple?
NSUserDefaults would probably be the easiest way
// To Save
[[NSUserDefaults standardUserDefaults] setString:myString forKey:kMyStringKey];
//To Load
NSString * myString = [[NSUserDefaults standardUserDefaults] stringForKey:kMyStringKey];
This will persistence between sessions.
Edit: This is assuming of course that the string is not constant for everyone using the program. If it is you can just hard code it. This is for if every instance of the app needs a different string, but you want the string saved between runs of the app.