Hey, I am trying to cache info on my IPhone App, but don't even know where to get started, I would to just cache a string (ex: 123123-12313123-1231231-123123), so when the user comes back it will remember it.
Is there a tutorial I can follow some where or could someone provide me some code?
Thanks
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
[userDefaults setString:#"123123123" forKey:#"myKey"];
[userDefaults synchronize];
Later, when you wish to retrieve this object:
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
NSString *myString = [userDefaults stringForKey:#"myKey"];
You'll, of course, want to manage the keys properly, etc.
Related
I'm saving my class instance with some data (images, strings, arrays etc) inside to my NSUserDefaults using this code:
NSData *encodedData = [NSKeyedArchiver archivedDataWithRootObject:myClassInstance];
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults setObject:encodedData forKey:#"myClassData"];
[defaults synchronize];
I'm doing this to use this data if I won't have internet connection.
Does all this data load to memory with NSuserDefaults? Or it loads when i use this:
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSData *encodedData = [defaults objectForKey:#"myClassData"];
It will load when you call
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSData *encodedData = [defaults objectForKey:#"myClassData"];
I am not sure when the data is loaded, but according to guidelines by Apple, you should not use nsuserdefaults to store any amount of data, as it is slow. You should just write the data as a file. NSDictionary and NSArray can write them self to file and read back directly.
You really should not do this. NSUserdefaults is only thought for doing preferences and settings, very small stuff
At the start of my application i make my users to register first then take them to login View.I want to save the successfully registered users and let them get to the loginView instead of Register View.
How can i do this.As far i know iphone is registered as one user.Tell me what is the best way.And how to keep the user data and redirect to login view for a user?
Thanks
You can use NSUserDefaults to save user data such as login info.
Take a look at this tutorial and the reference
In Short, you would do something like:
Saving after registration:
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
[prefs setObject:#"UserName" forKey:#"UserName"];
[prefs setObject:#"Pass" forKey:#"Pass"];
// This is suggested to synch prefs, but is not needed
[prefs synchronize];
Retrieving on app start:
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
NSString *userName = [prefs stringForKey:#"UserName"];
NSString *pass = [prefs stringForKey:#"Pass"];
I'm trying to create an application, and in that I'm receiving some contents from net and loading into and array, if I quit and run the app again i'm losing the data. How can I store the data in the app itself. Should I use some kind of database? If so which one and how can I implement that? I need to store only some string variables.
EDIT:
My app is tabbar based app, and have two tabs. Loading the arrays in one tab and loading that array in a table in the other VC. once I load the array and move to the second tab, the table is loaded with the array. If i go back and add few more values and then if i check, the added datas is not displayed in the table. And also, when I quit the app the table lose all the values, I need to keep the values in the table, even after i quit the app. How can I do that?
here is my code:
in viewdidload:
NSUserDefaults *simplePlistDb = [NSUserDefaults standardUserDefaults];
[simplePlistDb setBool:YES forKey:#"isItWorking"];
[simplePlistDb setObject:alertList forKey:#"myArray"];
[simplePlistDb synchronize];
in cellforrowatindexpath:-
NSUserDefaults *simplePlistDb = [NSUserDefaults standardUserDefaults];
BOOL flag = [simplePlistDb boolForKey:#"isItWorking"];
if (flag)
{
NSArray *myArray = [simplePlistDb objectForKey:#"myArray"];
for (NSString *str in myArray){
NSLog(#"Str:%#", str);
[loadArray addObject:str];
}
cell.textLabel.text = [loadArray objectAtIndex:indexPath.row];
}
Thank you.
You will want to look into Core Data if you want to save a decent amount of data to the iPhone. However, if not, you can just load the items in the array into a plist and load them from there at launch.
Plist Writing: How to create a new custom property list in iPhone Applications
CoreData: http://www.raywenderlich.com/934/core-data-tutorial-getting-started
Edit--->
As Nekto said, you can also use NSUserDefaults, but I advise mainly using NSUserDefaults for simple NSStrings and integers.
I think for your purposes NSUserDefaults will be enough : NSUserDefaults Class Reference.
Examples:
// save
NSUserDefaults *simplePlistDb = [NSUserDefaults standardUserDefaults];
[simplePlistDb setBool:YES forKey:#"isItWorking"];
[simplePlistDb setObject:[NSArray arrayWithObjects:#"very", #"cool", nil]];
[simplePlistDb synchronize];
// restore
NSUserDefaults *simplePlistDb = [NSUserDefaults standardUserDefaults];
BOOL flag = [simplePlistDb boolForKey:#"isItWorking"];
if (flag)
{
NSArray *myArray = [simplePlistDb objectForKey:#"myArray"];
for (NSString *str in myArray)
NSLog(#"%#", str);
}
You can use NSUserDefaults in order to store your data till the time your app is installed in your device.
How to write in NSuserDefaults:
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults setObject:#"yourObject1" forKey:#"correspopndingKey1"];
[defaults setObject:#"yourObject2" forKey:#"correspopndingKey2"];
[defaults synchronize];
How to read from NSuserDefaults:
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *temp1 = [defaults objectForKey:#"correspopndingKey1"];
NSString *temp2 = [defaults objectForKey:#"correspopndingKey2"];
You can store NSArray in a similar way.
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults setObject:objArray forKey:#"correspopndingKey"];
[defaults synchronize];
I'm writing an app for the iPhone that I've already created in Android and Blackberry and was hoping that there was an equivalent for SavedPreferences in iOS. Specifically I'm looking for the functionality to be able to create favorites on the fly. So in Android I can save a string into SavedPreferences with the identifier of "server project favorites". Is there something similar I can do in iOS without bothering with a SQL database for simple strings?
I think NSUserDefaults is what you are looking for.
Example with an array for server project favorites:
// Saving
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSArray *favorites = [NSArray arrayWithObjects:#"Favorite 1", #"Favorite 2", nil];
[defaults setObject:favorites forKey:#"favorites"];
// Retrieving
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSArray *favorites = [defaults arrayForKey:#"favorites"];
You're looking for NSUserDefaults
I have the following code in my initialization (first time) of my app:
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *uid=#"1";
[defaults setObject:uid forKey:#"init_val"];
[defaults synchronize];
Much later in the code (in response to a button press) I check the value using:
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *initVal=[defaults objectForKey:#"init_val"];
initVal is always nil. I have checked and init_val is set up exactly the same in my settings bundle as another field that I can set and read from without issue (they are both set up with a single field named "Key".
#mlewis54:
You can try this code. I am very sure that it will work for you.
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *uid=#"1";
[defaults setObject:uid forKey:#"init_val"];
[defaults synchronize];
For Retrieving Data You Should Use The Following Code :
NSString *initVal=[[NSUserDefaults standardUserDefaults] valueForKey:#"init_val"];
OR
NSString *initVal=[[NSUserDefaults standardUserDefaults] objectForKey:#"init_val"];
EDIT:
If still it gives nil, then you can use the following code:
NSString *initVal=[NSString stringWithFormat:#"%#",[[NSUserDefaults standardUserDefaults] valueForKey:#"init_val"]];
OR
NSString *initVal=[NSString stringWithFormat:#"%#",[[NSUserDefaults standardUserDefaults] objectForKey:#"init_val"]];
Hope this helps you.
Decelare this at an event on click of button ...
NSUserDefaults *savedData = [NSUserDefaults standardUserDefaults];
[savedData setObject:userEmailTextField.text forKey:#"userid"];
and on load load the data and check the value you have entered is showing or not...
userEmailTextField.text =[[NSUserDefaults standardUserDefaults]objectForKey:#"userid"];
You need to use the line
NSString *initVal = [defaults stringForKey:#"init_val"];
- since it's a String you must use stringForKey. You can similarly use boolForKey to get a boolean value.
There's nothing wrong in your code, i tried to copy it in my project and it worked good,
so your error could be probably when you check initVal...
what's the code you use to see if initVal is nil?
and are you sure that when/where you check initVal, that var/oblect is still visible ?
try to insert this immediately after your reading code:
NSLog(#"____text read in pref: %#", initVal);
it writes this in my console window -> __text read in pref: 1
of course it's an NSString, i hope you keep it in mind it's not an int or a NSNumber when you check it...
luca
It might be that the initialisation isn't happening. Put an NSLog in there to check it's executed.
It works fine for me with the same code:
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *uid=#"1";
[defaults setObject:uid forKey:#"init_val"];
[defaults synchronize];
NSUserDefaults *defaultss = [NSUserDefaults standardUserDefaults];
NSString *initVal=[defaultss objectForKey:#"init_val"];
NSLog(#"Value of initVal: %#",initVal);
O/P on console: Value of initVal: 1
So try to do it with the same code with print on console.
Are you sure you properly initialize NSUserDefaults? When I initialize, in my app delegate, I always create the default user defaults by creating a dictionary of the default values then:
[[NSUserDefaults standardUserDefaults] registerDefaults:appDefaults];
Where appDefaults is the dictionary. Then you should be able to access them correctly.