Could you give me some algorithm or example?
NSUserDefaults will nicely hold onto snippets of data.
Example:
- (void)applicationDidFinishLaunching:(UIApplication *)application {
[window addSubview:tabBarController.view];
if ([[NSUserDefaults standardUserDefaults] integerForKey:kTabIndexKey])
tabBarController.selectedIndex = [[NSUserDefaults standardUserDefaults] integerForKey:kTabIndexKey];
}
- (void)applicationWillTerminate:(UIApplication *)application {
[[NSUserDefaults standardUserDefaults] setInteger:tabBarController.selectedIndex forKey:kTabIndexKey];
}
Persists and loads an integer (your method would be "setString" and "stringForKey", check the docs.)
Related
I am trying to change the Root View controller if the application has been opened once. Here is what im doing. The boolean is fully functional and i know because it prints 'Welcome Back'. Here is what im trying to do.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// Override point for customization after application launch.
if ([[NSUserDefaults standardUserDefaults] boolForKey:#"HasLaunchedOnce"])
{
// App Already launched
RootMenuController *viewController = [[RootMenuController alloc] init];
[UIApplication sharedApplication].keyWindow.rootViewController = viewController;
}
else
{
[[NSUserDefaults standardUserDefaults] setBool:YES forKey:#"HasLaunchedOnce"];
[[NSUserDefaults standardUserDefaults] synchronize];
// This is the first launch ever
}
[self.window makeKeyAndVisible];
return YES;
}
It seems like you are not setting/updating application window properly. I have created an sample project which might help. https://github.com/deepthit/UpdateRootViewController.git
Say for example if I have two buttons one for apples and one for orange, and I select apples and takes me to the apples screen. How can I make it for now on every time I run the app it will go to the apples screen?
in viewDidLoad
if([[NSUserDefaults standardUserDefaults] objectForKey:#"fruit"] != nil)
{
if ([[[NSUserDefaults standardUserDefaults] objectForKey:#"fruit"]isEqualToString:#"apple"]) {
[self.navigationController pushViewController:appleVC animated:NO];
}
else{
[self.navigationController pushViewController:orangeVC animated:NO];
}
}
and on Button Methods
on Apple button
[[NSUserDefaults standardUserDefaults] setObject:#"apple" forKey:#"fruit"];
on Orange button
[[NSUserDefaults standardUserDefaults] setObject:#"orange" forKey:#"fruit"];
You can store information like this using NSUserDefaults.
You'd store a boolean bAppleSelected like this:
NSUserDefaults * standardUserDefaults = [NSUserDefaults standardUserDefaults];
[standardUserDefaults setBool:bAppleSelected forKey=#"appleSelected"];
You can read it by accessing the default userDefaults:
BOOL bApple = [standardUserDefaults boolForKey=#"appleSelected"];
On your app delegate you must have some method that instantiates the very first controller and displays it in a window. You can just create an "apples controller" and push it there
You can use NSUserdefaults here,
NSString* fruit=#"apple";
[[NSUserDefaults standardUserDefaults]setObject:fruit forKey:#"controllerName"];
[[NSUserDefaults standardUserDefaults]synchronize];
and insted of the name string of your firstview controller in appdelegate file use the above NSUserDefaults.
I'm trying to make some sort of setup wizard that remembers a specific view however I have some problems with my AppDelegate.m code since I'm using ARC.
Does anyone know how to fix this, because If I compile the app crashes at the splash screen..
My AppDelegate.m:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
NSString *controllerName = [[NSUserDefaults standardUserDefaults] objectForKey:#"WIZARD_VIEW"];
if ([controllerName length]) {
Class controllerClass = NSClassFromString(controllerName);
UIViewController *controller = [[controllerClass alloc] init];
// Override point for customization after application launch.
return YES;
}
To be more clear, in the viewcontroller files I added the following code as a suggestion:
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
[[NSUserDefaults standardUserDefaults] setObject:[[self class] description] forKey:#"WIZARD_VIEW"];
NSLog(#"ViewWillAppear Done.");
[[NSUserDefaults standardUserDefaults] synchronize];
}
- (void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
[[NSUserDefaults standardUserDefaults] removeObjectForKey:#"WIZARD_VIEW"];
NSLog(#"viewWillDisappear");
[[NSUserDefaults standardUserDefaults] synchronize];
}
Crashlog while compiling:
/Users/Tim/Documents/XCODE_DEV/App/AppDelegate.m:17:33: No visible #interface for 'NSUserDefaults' declares the selector 'forKey:'
/Users/Tim/Documents/XCODE_DEV/App/AppDelegate.m:20:27: Unused variable 'controller'
The first time you have to register the defaults.To register the defaults isn't enough to call the setObject:forKey method, you have to use the registerDefaults method:
- (void)registerDefaults:(NSDictionary *)dictionary;
Documentation:
NSUserDefaults
So in your case:
NSUserDefaults* standard=[NSUserDefaults standardUserDefaults];
[standard registerDefaults: #{ #"WIZARD_VIEW" : [[self class]description]} ];
You better place these lines in the initialize method, which gets called before any non-static method.If the defaults are already registred there's no problem, this will not overwrite the defaults that you have if is the 2nd+ time that the application starts.
Looking at the compiler warnings, I'm going to guess that in your AppDelegate.m, on line 17 you are calling forKey: on NSUserDefaults.
NSUserDefaults doesn't have a forKey: method, so it throws an exception.
It's probably just a square bracket in the wrong place.
I'm trying to play an intro movie when my app is getting launch, but am totally driven crazy already, I did a lot of testing in my code, along with trying to use this
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// Override point for customization after application launch.
NSLog(#"App started to launch");
[self.window makeKeyAndVisible];
[self.window addSubview:_intro.view];
return YES;
}
but that's make my video run, even if I'm coming from the background.
If like pressing the middle button, then double pressing the middle button and pressing app icon, I get the movie to play again.
I forget to mention that this is my ViewDidLoad
- (void)viewDidLoad
{
[super viewDidLoad];
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
BOOL launchedBefore = [userDefaults boolForKey:#"hasRunBefore"];
NSLog(#"value of hasRunBefore is %d",launchedBefore);
if(!launchedBefore)
{
[userDefaults setBool:1 forKey:#"hasRunBefore"];
launchedBefore = [userDefaults boolForKey:#"hasRunBefore"];
NSLog(#"value of hasRunBefore is %d",launchedBefore);
[self playvideo];
}
}
NSUserDefaults does not commit the changes to disk until you send the synchronize message.
Try adding doing this:
[userDefaults setBool:YES forKey:#"hasRunBefore"];
[userDefaults synchronize];
So i'm trying to use this method to load a certain theme based on what the user chose in the settings bundle. When I insert NSLog it will load the default them (Modern Theme), but it will never change to the Pink Theme.
Is this method loaded every time the app is launched, even if the app is still running in the background.
Otherwise, where else could I do this, if I want to use the settings bundle.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
NSDictionary *userDefaultsDefaults = [NSDictionary dictionaryWithObjectsAndKeys: #"Modern Theme", #"theme", nil];
[[NSUserDefaults standardUserDefaults] registerDefaults:userDefaultsDefaults];
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
theme =[defaults objectForKey:#"theme"];
NSLog(#"%#", theme);
if ([theme isEqualToString:#"Modern Theme"]) {
viewController = [[viewTwo alloc] initWithNibName:#"viewTwo" bundle:nil];
}
else {
viewController = [[viewOne alloc] initWithNibName:#"viewOne" bundle:nil];
}
self.window.rootViewController = self.viewController;
[self.window makeKeyAndVisible];
return YES;
}
Have you tried putting your code in applicationDidBecomeActive:? That one is guaranteed to be called whether on the initial launch or resuming from the background.
Reference docs.
The method
- (void)applicationWillResignActive:(UIApplication *)application
is fired when the app is resumed from the background.
I'd nearly load the theme in the ViewController's
-(void)viewDidAppear:(BOOL)animated
method.