The application I'm working on creates pdf files and saves them in the device's documents directory. What I'm trying to do is create filenames with unique ID number, for example "invoice76.pdf".
How do I ensure each time the pdf file is created the number is incremented from the previous file name.
I tried using a global int but that obviously resets it each time the application is started.
Probably the simplest solution would be to store it in the NSUserDefaults. Alternatively, you could save the value in your own plist file.
Use this code which works betweeb app restarts:
- (void)storeIndex:(NSInteger)index{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
//change value to new value
[defaults setInteger:index forKey:#"pdfIndex"];
//make save
[defaults synchronize];
}
- (NSInteger)lastIndex{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSInteger value = [defaults integerForKey:#"pdsIndex"];
return value;
}
//stores new index and returns its value
- (NSInteger)incrementIndex{
NSInteger lastIndex = [self lastIndex];
lastIndex++;
[self storeIndex:lastIndex];
return lastIndex;
}
Pull an nsstring timestamp from nsdate, and if saving multiple files at the same time (and you don't want to use a massive timestamp) increment through n in a for loop. This will guarantee a unique ID. Then when loading, sort your array ascending and you have your list.
I am developing iPhone app,i have one doubt
I have an NSMutableDictionary which contains data in this format
dict at 0th index:
"ProductId":"77386",
"ProductImage":"http://static.abcd.com/images/product/large/design_gallery_slide_green - Copy (2).jpg",
"Productshortname":"Apple iPhone 5c 16GB",
"categorycode":null,
"categoryid":8,
"categoryimage":"",
"categoryshortname":"",
"favorite":"0",
"price":"31500",
"productnameinUrl":"apple-iphone-5c-16gb",
"storecount":"10"
dict at 1st index:
"ProductId":"11386",
"ProductImage":"http://static.abcd.com/images/product/large/design_gallery_slide_green - Copy (2).jpg",
"Productshortname":"Apple iPhone 5s 16GB",
"categorycode":null,
"categoryid":8,
"categoryimage":"",
"categoryshortname":"",
"favorite":"1",
"price":"31500",
"productnameinUrl":"apple-iphone-5s-16gb",
"storecount":"18"
dict at 2nd index:
"ProductId":"31386",
"ProductImage":"http://static.abcd.com/images/product/large/design_gallery_slide_green - Copy (2).jpg",
"Productshortname":"Apple iPhone 4s 16GB",
"categorycode":null,
"categoryid":8,
"categoryimage":"",
"categoryshortname":"",
"favorite":"1",
"price":"31500",
"productnameinUrl":"apple-iphone-4s-16gb",
"storecount":"38"
and so on...
What i want to do is, i want to store this dictionary indexes some where in my directory and i want to fetch it after some time or even after closing and opening the app after few times.
where should i store this kind of data ? is there any storage for strong this kind of data?
Please help and thanks in advance !!
You can store the data in NSUserdefaults and can access any time and anywhere as you want
yourdict;//Your NSDictionary Object That contains the data to store
[[NSUserDefaults standardUserDefaults] setObject:yourdict forKey:#"dict"];
[[NSUserDefaults standardUserDefaults] synchronize];
At the time of retrieval of data,
dict = [[NSUserDefaults standardUserDefaults] objectForKey:#"dict"];
You've already chosen an approved answer but I'll throw my thoughts in anyway.
This information looks like it could get large.
The user defaults isn't designed for large chunks of data. It's really meant for small bits of information, such as boolean preferences etc etc, not to be treated as an easy-to-use database.
Some problems with the user defaults:
The defaults file is read and parsed when you launch your app, regardless of whether you need your information from it at that time or not. This is because other parts of your app also use it for storing their bits of info too.
The entire defaults file needs to be parsed in order for you to retrieve anything, even if you just want a single entry.
You don't choose when the defaults file is parsed. You can't do any smart threading if it becomes huge (say you put 1000 products in there)
I'd recommend either writing the dictionary to it's own plist using NSDictionary's writeToFile: and reading using initWithContentsOfFile: (this still suffers from point #2 above)
OR
Using CoreData/sqlite to write the information to a real database.
NSDictionary methods: https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/Reference/Reference.html#//apple_ref/occ/instm/NSDictionary/writeToFile:atomically:
An other option (And better in my experience) is to use - NSCoder, this option is great as you can use an Object with normal properties to access your data, which make your code more readable.
You can read about it here - NSCoding / NSKeyed​Archiver by NSHipster
An here is the reference - NSCoder docs
NSDictionary has a writeToFile: method which will do it for you.
NSDicationary writeToFile:Atomically:
use NSUserDefault and save your data like this in array
Here you can use this in anyway in your application for store value of NSUserDefaults.
// --- Saving
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
// saving an NSString
[prefs setObject:#"TextToSave" forKey:#"keyToLookupString"];
// saving an NSInteger
[prefs setInteger:42 forKey:#"integerKey"];
// saving a Double
[prefs setDouble:3.1415 forKey:#"doubleKey"];
// saving a Float
[prefs setFloat:1.2345678 forKey:#"floatKey"];
// This is suggested to synch prefs, but is not needed (I didn't put it in my tut)
[prefs synchronize];
Here you can use this in anyway in your application for get value of NSUserDefaults.
// --- Retrieving
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
// getting an NSString
NSString *myString = [prefs stringForKey:#"keyToLookupString"];
// getting an NSInteger
NSInteger myInt = [prefs integerForKey:#"integerKey"];
// getting an Float
float myFloat = [prefs floatForKey:#"floatKey"];
Thanks & Cheers ..
Looks like there can be more amount of data, so the best approach is to use core data to handle this scenario.
You can check few tutorials on how to use core data - Link1 , Link2
There are advantage of using core data over NSUserDefault and file system, as those load all the data at once and you might face some issue in performance.
You can also check following links which will illustrate you performance of different mechanism used to store data - PerformanceLinks1 PerformanceLinks2
try this
NSMutableDictionary *dictionary = [NSMutableDictionary dictionaryWithObjectsAndKeys:
#"audio.caf",#"pictureAudioKey",
#"audio.m4a",#"englishAudioKey",
#"audio2.m4a",#"spanishAudioKey",
#"audio3.m4a",#"frenchAudioKey",
#"audio4.m4a",#"germanAudioKey",
#"audio5.m4a",#"italianAudioKey",
#"audio6.m4a",#"chineseAudioKey",
#"image.jpg",#"photoimagekey",
#"name.txt", #"identity",
#"imagename.txt",#"numberkey",nil];
NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [documentPaths objectAtIndex:0];
NSString *dictionaryPath = [documentsDirectory stringByAppendingPathComponent:[[self imageNameTextField]text]];
dictionaryPath =[dictionaryPath stringByAppendingFormat:#"dicitonary" ] ;
NSDictionary *savedDictionary = dictionary;
NSLog(#"The Save file is:%#", savedDictionary);
[savedDictionary writeToFile:dictionaryPath atomically:YES];
I want to save some user preferences, but
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
just returns nil.
iOS-Developper Library says, that this should return the existing shared defaults object or create one if none exists... What am I missing?
I also use Appirater and there all this stuff seems also not to work...
This code gets called when the user pushes a button...
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
int index = ([defaults integerForKey:#"BackgroundColorSpecifier"]+ 1)%self.backgroundColors.count;
[defaults setInteger:index forKey:#"BackgroundColorSpecifier"];
[defaults synchronize];
This gets called in application: didFinishLaunchingWithOptions:
NSUserDefaults *standardDefaults = [NSUserDefaults standardUserDefaults];
[standardDefaults registerDefaults:#{#"BackgroundColorSpecifier": #0}];
[standardDefaults synchronize];
When I debug this code snippets the green "position-indicator" jumps around in a very strange manner...
I don't have any clue, whats going on... Please help!
This is far more likely to be a problem with the debugger than anything else, particularly with your other issues. I've seen similar things in my own projects but don't have a reliable way of clearing it out other than the usual restart / clean options.
NSLogs will usually give more consistent results than the debugger if the debugger is having an off day.
NSUserDefaults isn't broken. We'd have heard about it by now.
you can use this function to log you userDefaults dic
- (void)logCache
{
NSDictionary * dic = [[NSBundle mainBundle] infoDictionary];
NSString *bundleId = [dic objectForKey: #"CFBundleIdentifier"];
NSUserDefaults *appUserDefaults = [[NSUserDefaults alloc] init];
NSDictionary *cacheDic = [appUserDefaults persistentDomainForName: bundleId];
NsLog(#"cacheDic::%#",cacheDic);
}
Ive made a simple ios utility application in xcode (version 4.4.1) but Ive realised that I need to store one integer in persistent memory. As far as I know using core data is the best way to achieve this.
Ive added the core data framework to my app but I dont know the code that I need to add for it to work.
Could someone please help
Thanks
If you just need to store/retrieve an integer, NSUserDefaults should be the way to go.
Saving
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
// saving an NSInteger
[prefs setInteger:42 forKey:#"integerKey"];
// This is suggested to synch prefs, but is not needed (I didn't put it in my tut)
[prefs synchronize];
Retrieving
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
// getting an NSInteger
NSInteger myInt = [prefs integerForKey:#"integerKey"];
Reference:
http://www.icodeblog.com/2008/10/03/iphone-programming-tutorial-savingretrieving-data-using-nsuserdefaults/
I have two viewcontrollers. In my first viewcontroller:
{
NSString *string=textField.text;
NSUserDefaults *data = [NSUserDefaults standardUserDefaults];
[data setObject:string forKey:#"strings"];
[data synchronize];
}
How do I get the string value in my other viewcontroller?
Here you can use this in anyway in your application for store value of NSUserDefaults.
// --- Saving
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
// saving an NSString
[prefs setObject:#"TextToSave" forKey:#"keyToLookupString"];
// saving an NSInteger
[prefs setInteger:42 forKey:#"integerKey"];
// saving a Double
[prefs setDouble:3.1415 forKey:#"doubleKey"];
// saving a Float
[prefs setFloat:1.2345678 forKey:#"floatKey"];
// This is suggested to synch prefs, but is not needed (I didn't put it in my tut)
[prefs synchronize];
Here you can use this in anyway in your application for get value of NSUserDefaults.
// --- Retrieving
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
// getting an NSString
NSString *myString = [prefs stringForKey:#"keyToLookupString"];
// getting an NSInteger
NSInteger myInt = [prefs integerForKey:#"integerKey"];
// getting an Float
float myFloat = [prefs floatForKey:#"floatKey"];
you can access NSUserDefaults in any controller (Any class of your application) of your application with the same code you have written in one class.
for getting the string value use the below code
NSUserDefaults *data = [NSUserDefaults standardUserDefaults];
NSString *myString = [data objectForKey:#"strings"];
NSUserDefaults * defaults = [NSUserDefaults standardUserDefaults];
NSString *myString = [defaults stringForKey:#"strings"];
THis is the way to retrieve the data. Please note NSUserDefault is not used to pass data between two controllers. There are better methods for that.
Edit : After seeing Shaan Singh's comment
To pass data 2 view controllers you can declare a property in second view controller and access that from the present view controller.
It is already answered brilliantly here.
In the other ViewController,
NSUserDefaults *data = [NSUserDefaults standardUserDefaults];
NSString *string = [data objectForKey:#"strings"];
This will work because NSUserDefaults are a global key-value store that will persist across classes and applications.