Using NSUserDefaults to save/load a few small values... it's pretty straightforward.
But WHERE would I place my SAVE or LOAD code?
I want the defaults to LOAD only if/when a certain view is displayed.
I want the defaults to SAVE, only when that view is exited/unloaded/hidden.
(I created a simple app using the "view-based template" and have my string values on the view, inside of UITextFields.)
How about the viewWillAppear and dealloc/viewDidDisappear methods of that view's UIViewController?
Well, your talking about views so:
viewDidLoad / viewWillLoad
viewDidUnload / dealloc
Seem like good candidates. Also, in your init methods, especially if you want to initialize iVars at that point to something from NSUserDefaults.
You should always put the code itself into its own file pair to manage the user defaults, and this module should be responsible for serialization and deserialization, though objects that are serialized should own that virtuosity themselves. You get only the settings you absolutely need in viewDid Load, so as not to slow down the initialization.
If you have capacious user settings, arrays and dictionaries, multiple session data, don't make the mistake of storing them under a single dictionary and key. Split them up.
If your app requires users log on (I do crypto so most of mine do) then only after logon, verifying password from a minimal load of user settings, should you go on to load the heavier session settings. This is on "user time" anyway.
Related
so I have a UITableView and within each cell, a UITextView. I want the user to be able to edit each UITextView as many times as they like, then go back to somewhere else in the app, close the app, whatever, and then come back and see the same thing they wrote. I have not been able to figure out how to do it.
Please help. I'm still pretty new to Swift.
This is a design problem. Anyway my suggestion is to add a flag in your data model.
Data model (the data that you are presenting in your table). If you don't have any data model, add one.
Example:
class UserInformation {
name: String
isEditing: Bool = false
}
and then save this in your preferred location either in DB (core data, realm etc) or plist (which i don't recommend)
now during the creation of cell. You could just check if this is in editing mode. And then fill up the text field using the saved data.
EDIT: You can't just magically know/retain a state in an object without persisting.
You want to store textView informations in any case, including terminating application, there are some steps to implement this feature.
At first, you have to pick up a place for storing your information:
Hard disk
Your own server
Other service (firebase ...)
RAM is not useable in this case.
Supposing you like hard disk option, let's select a method for storing:
Create a file (JSON, text file, ...), save your information every time user enter a new one, open it to get information back.
Save it by CoreData / Realm in database way (CoreData is like SQL lite, a lite weight database for mobile application supported by Apple)
In my project, I have an NSArrayController bound to save to a the application's standard defaults (NSUserDefaults). This in itself works perfectly - objects added are saved and restored as expected.
However, if I programmatically modify one of the NSMutableDictionaries contained in the NSArrayController's array, none of the changes are saved. Only values set with the creation of the dictionary seem to stick.
I suspect this is because simply calling setObject:forValue: on the dictionaries in the array doesn't notify the controller of changes, but I'm not sure. Am I doing something wrong?
UPDATE: I have since switched from NSMutableDictionary to a custom object that conforms to KVC (to the best of my knowledge - I'm using properties so that should be taken care of) as well as NSCoding. It can and does save and restore fine - it's just not consistent. It kinda saves whenever it feels like it instead of when I update a property.
Well, I ended up just writing my own controller responsible for loading and saving downloads to their own plist file. It saves when it's told to without fail, so the problem is solved.
I am new in iphone development and i needed a array which i use to access in different class so my senior told me that you should declare in App delegate and access it another class in which it require, so i wrote line for that
MyAppAppDelegate * appObject =
(MyAppAppDelegate*)[[UIApplication sharedApplication]delegate];
I done my task successfully but i couldn't get it 100%. Someone tell that why we use this and in what exactly situation in which we've to use this?
AppDelegate is loaded first when you run your application as it contains window. So, the variable and objects you want to access throughout your project is declared in AppDelegate. You just have to create an instance and you can access all the objects in AppDelegate.
ApplicationDelegate can be useful as a singleton class but you have to use it with discretion - and there are varying opinions on this - but if you have a few global type properties or methods you want to recall from various other classes, and I emphasize few, then ApplicationDelegate may be a nice place to add these.
And yes, it is bad design - but you can get away with it if you are prudent and as #Sedate Alien mentions, take a look at dependency injection.
The purpose of ApplicationDelegate, by the way, is mainly to handle events like loading your application, when you return to home screen, when you come back from home screen, etc.
Any code examples for using a UITableView to implement in-app settings?
That is where to get the iPhone settings app look and feel one custom builds the settings into a UITableView. So you you would custom set the sections and cells that get returned with switch type statements.
In particular interested in reviewing the coding approach for how to:
best configure the cellForRowAtIndexPath and didSelectRowAtIndexPath
how to handle those cells for which you want in cell editing (e.g. text)
those cells where you need to launch off into another screen to set a date/time for example
how to collect up parameters and pass back to calling rootViewController (in my case need to persist data out to Core Data persistence)
Note: using Core Data so not interested in using libraries such as InAppSettings [any feedback re whether such libraries might be ok appreciated at this SO question I created].
thanks
I am not sure if you can use the inappsettingskit for your needs. It is open source so you are free to modify the code as you wish, but it doesn't look as an out of the box solution.
If you want to make these settings available in the settings app you will have to live with some workarounds for example saving NSDate AND getting a nice UI control to modify it: Use a textfield, there is no control specified which let's you pick a date. Have a look at Apple's documentation.
So the last option will be coding. First of all, determine what kind of types you want to support. Then create custom TableViewCells which reflect those kinds. If some kinds do need some special way of editing, for example a color picker, you'll have to write those controllers as well. You set a cell into editing mode with the delegate method tableView:didSelectRowAtIndexPath and present the custom controller or get into editing directly for example a UITextField. A Slider is handled directly without any coding.
The cells will need some kind of identifier so you can identify those in your model. A TableView and Core Data can interact with each other pretty well by using the NSFetchedResultsController. Create a simple window based app with a template and check the Use Core Data for Storage. The rootViewController illustrates how a tableView works together with Core Data. For your case it will be getting a bit more complicated as inserting a row will have to determine what kind of cell it should add.
I think you should look into this and get back with some more specific questions.
I'm trying to write an iphone OS app that includes a logbook feature. The problem that I'm having is that I want each new logbook to have its own categories that are user-defined, for example a chemical receipt log would have chemical name, vendor, receipt date, expiration date and comments.
The way that I'm trying to go about this is by calling an editCategory view controller when a new logbook is created that contains a number of UITextields where the user can enter the categories. I want to take those strings and apply them to a newLogEntry view controller, so that when the user creates a new log entry, they are presented with each category followed by a UITextfield so they can enter the relevant data.
The trick is, I have no idea how to grab the category data from editCategory and apply it to newLogEntry. I'm currently using Core Data, as that seems to be the easiest way to go about this, but I'm not married to it if it interferes with a good solution. Also, I'm still more comfortable with genetic code than objective-C code, so please bear with my ignorance.
Have you considered using the App Delegate? You could keep those values in the App Delegate, and call on them in the ViewDidLoad method of your newLogEntry view controller.