Is this code correct to load and save NSUserDefaults.
// Load
NSDictionary *dict = [[NSUserDefaults standardUserDefaults]
dictionaryRepresentation];
// Save
NSDictionary *dict = ....
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults registerDefaults:dict];
[defaults synchronize]; << Not sure if this is needed
I'm using JSON to hold the dictionary contents and I'm having problems.
I'd just like to know if this code is correct, before I look elsewhere for my problem.
Your Load code will get you a dictionary of all the current default values.
[Note This will probably be much larger than you expect as Mac OS installs a raft of defaults, you might want to make it smaller. For example, you can limit the dictionary to just those defaults in your domain which differ from their registered default using:
NSDictionary *userDefaults = [[NSUserDefaults standardUserDefaults] persistentDomainForName:#"<your bundle identifier>"];
end note]
Your Save code probably doesn't do what you expect, it installs the values you are restoring as the defaults for those keys - so if you support "Restore to Default Settings", or something similar, then these are the values that would result. What you probably want to do it set the current value of the keys, this can be done with a simple loop:
NSDictionary *dict = ....
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
foreach(id key in dict)
[defaults setObject:[dict objectForKey:key] forKey:key];
The above code is only an outline, you may need to take care what preferences you save/restore and in what order - but all that depends on your application.
// Get
NSDictionary *dict = [[NSUserDefaults standardUserDefaults] objectForKey:#"myDictionary"];
// Set
NSDictionary *dict = ...
[[NSUserDefaults standardUserDefaults] setObject:dict forKey:#"myDictionary"];
Related
I would like to save Array/NSDictionary to NSUserDefaults but anything I try is just not working. Here is my code so please if you know how to do this, help me.
NSArray *oneArray = [NSArray arrayWithObjects:#"Radio One",nil];
NSDictionary *one = [NSDictionary dictionaryWithObject:oneArray forKey:#"Stations"];
NSArray *oneLinkArray = [NSArray arrayWithObjects:#"http://mobile.com:28000/",nil];
NSDictionary *oneLink = [NSDictionary dictionaryWithObject:oneLinkArray forKey:#"Stations"];
[data addObject:one];
[link addObject:oneLink];
The reason I need this is to put this station into favorites. So my thinking is to save these info in to NSUserDefaults and retrieve in favorites table.
Thanks and please any suggestion is welcomed and appreciated.
You can use something like this when you store everything into a dictionary
[[NSUserDefaults standardUserDefaults] setObject:link forKey:#"dictionary1"];
Or you can put everything into an array and store it like this
[[NSUserDefaults standardUserDefaults] setObject:data forKey:#"array1"];
You can access it again by using
NSDictionary * myDictionary = [[NSUserDefaults standardUserDefaults] dictionaryForKey:#"dictionary1"];
Typically adding an object into NSUserDefaults goes like this:
NSMutableDictionary *dictionaryToAdd = [[NSMutableDictionary alloc] init];
[dictionaryToAdd setObject:#"xyz" forKey:#"myKey"];
NSUserDefaults *myDefaults = [NSUserDefaults standardUserDefaults];
[myDefaults setObject:dictionaryToAdd forKey:#"someKey"];
[myDefaults synchronize];
A few things on your code above though - you're adding stuff into 'data' and 'link' but I don't see those in your code, so I'm assuming those arrays exist somewhere.
To sum it up - declare an NSUserDefaults object, set objects into it like an NSDictionary, and then synchronize it to save data.
Additional code as requested:
//You have an array named arrayToAdd that has already been created
NSUserDefaults *myDefaults = [NSUserDefaults standardUserDefaults];
[myDefaults setObject:arrayToAdd forKey:#"SomeKeyThatYouMakeUp"];
[myDefaults synchronize];
//You want to get the array out of NSUserDefaults
NSArray *mySavedArray;
NSUserDefaults *myDefaults = [NSUserDefaults standardUserDefaults];
mySavedArray = [myDefaults objectForKey:#"SomeKeyThatYouMakeUp"];
I'm storing all my data in NSUserDefaults.
Now I'm trying to store some keys with a specific prefix in an Array. Therefore, I first load the UserDefaults in a Dictionary.
NSString *myPrefix = #"prefix";
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSDictionary *dict = [defaults dictionaryRepresentation];
for (NSString *keyWithPrefix in dict.keyEnumerator) {
if ([keyWithPrefix hasPrefix: myPrefix]) {
[relevantKeys addObject: keyWithPrefix];
}
}
The Problem is: when I print "dict" (which represents UserDefaults). There are some keys missing.
Does NSUserDefaults delete keys, that are not needed temporarily?
Nope it does not, NSUserDefault is a persistance storage,
Please read the following answer it has a very good explanation
How persistent is [NSUserDefaults standardUserDefaults]?
No, but are you calling [NSUserdefaults synchronize] when you are updating them ?
You should probably be using -synchronize method when storing what you want. i,e:
[[NSUserDefaults standardUserDefaults] setValue:someDictionary forKey:#"someKey"];
[[NSUSerDefaults standardUserDefaults] synchronize];
I am trying to do following task
[[NSUserDefaults standardUserDefaults] setObject:#"Dry" forKey:#"vesselType_preference"];
[[NSUserDefaults standardUserDefaults] synchronize];
where my "vesselType_preference" is multivalue attribute, but it is not getting effected. Please help this is working for other type of attribute but not working for multivalue type.
Thanks
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
if (![defaults objectForKey:#"vesselType_preference"])
{
[defaults setObject:#"Dry" forKey:#"vesselType_preference"];
}
[[NSUserDefaults standardUserDefaults] synchronize];
This should work.
NSUserDefaults can only handle objects of NSDictionary, NSData, NSArray, NSString and BOOL. (There might be another in there, not sure) If you need to store a multiple value object like an array or dictionary, I would store your settings there first, then save that to the defaults.
Your code looks fine for storing information to the user defaults. Just make sure you have your object type specified before saving. (id) will not work... or won't work properly.
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 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.