I am trying to checking if a certain view has been loaded ever before in the lifetime of the app. I have implemented the following code but not quite sure why it isn't working. It is being done in the viewDidLoad method only of the view controller (perhaps this is the problem). If anyone can let me know what my mistake is, it would be appreciated. Thanks!
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
BOOL hasRunBefore = [defaults boolForKey:#"FirstRun"];
if (hasRunBefore) {
NSLog (#"not the very first time this controller has been loaded");
[defaults setBool:YES forKey:#"FirstRun"];
[defaults synchronize];
}
else if (!hasRunBefore) {
[defaults setBool:NO forKey:#"FirstRun"];
NSLog (#"the very first time this controller has been loaded");
[defaults synchronize];
}
There are a couple of mistakes in your code. See the corrections below:
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
BOOL hasRunBefore = [defaults boolForKey:#"FirstRun"];
if (hasRunBefore) {
NSLog (#"not the very first time this controller has been loaded");
/* Toggle the boolean state */
[defaults setBool:NO forKey:#"FirstRun"];
}
else if (!hasRunBefore) {
/* Toggle the boolean state */
[defaults setBool:YES forKey:#"FirstRun"];
NSLog (#"the very first time this controller has been loaded");
}
[defaults synchronize];
However, I am not sure why you would want to toggle the FirstRun back to NO in the if(hasRunBefore). I only point out what is wrong, you might want to check your logic again.
-EDIT-
Like I pointed out about your logic, you should only have this:
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
BOOL hasRunBefore = [defaults boolForKey:#"FirstRun"];
if (!hasRunBefore) {
[defaults setBool:YES forKey:#"FirstRun"];
[defaults synchronize];
NSLog (#"the very first time this controller has been loaded");
}
else
NSLog (#"Not the first time this controller has been loaded");
The values set in defaults are persistent for as long as the app is installed on the device.
You should think about using a BOOL value set in the app delegate (which does not persist from run to run)
OR
You should set "FirstRun" back to NO in your app delegate in the following method.
- (void)applicationWillTerminate:(UIApplication *)application
NSUserDefaults is a possibility, but you could also use a static BOOL and set it to YES when the view controller is loaded for the first time.
Related
I am new to Xcode and I am using Objective C in OSX.
I am trying to load the user’s last selected value for a slider when the app relaunches.
my code for the slider is…
- (IBAction)sliderChanged:(id)sender {
amount = [self.amountSlider integerValue];
NSString *amountString = [NSString stringWithFormat:#"%ld", amount];
[self.amountLabel setStringValue:amountString];
}
I have this setter…
- (void)setInteger:(NSInteger)valueforKey:(NSString *)defaultName{
[[NSUserDefaults standardUserDefaults] setObject:#"amountString" forKey:#"amountSlider"];
}
I would like to know how to code the getter.
A step-by-step instructions with code will be appreciated.
Any improvements/corrections to my existing code above would also be appreciated.
Make separate functions for retrieving, saving from defaults like this.
- (void)saveValueToUserDefaults:(NSString *)pValue key:(NSString *)kKey {
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[self removeValueFromUserDefaults:kKey];
[defaults setObject:pValue forKey:kKey];
[defaults synchronize];
}
- (void)removeValueFromUserDefaults:(NSString *)kKey {
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
if ([defaults objectForKey:kKey]) {
[defaults removeObjectForKey:kKey];
}
}
- (NSString *)retriveValueFromUserDefaults:(NSString *)kKey {
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
if ([defaults objectForKey:kKey]) {
return [defaults objectForKey:kKey];
} else {
return kStringEmpty;
}
}
This will make simple to save and retrieve values from defaults.
Like-
[self saveValueToUserDefaults:YOUR_AMOUNT forKey:YOUR_KEY];
and get like this,
YOUR_AMOUNT = [self retriveValueFromUserDefaults:YOUR_KEY];
You asked for it :D
in your class create integer variable called amountChecker = 0
create a function called checker like this :
-(void) checker {
if (amount == amountChecker){
[[NSUserDefaults standardUserDefaults] setObject:amountLabel.text forKey:#"amountSlider"];
}
else
amount = amountChecker;
}
then .. in this function :
- (IBAction)sliderChanged:(id)sender {
amount = [self.amountSlider integerValue];
NSString *amountString = [NSString stringWithFormat:#"%ld", amount];
[self.amountLabel setStringValue:amountString];
[self performSelector:#selector(checker) withObject:nil afterDelay:1];
}
now this code will only store your value if a second passes and your slider didn't change , instead of storing your value like 60 times every second :D
it all starts when you change the slider then after one second it will check if the value changed if not it will store it
and when you reopen the app you will use this code :
amount = [[NSUserDefaults standardUserDefaults] objectForKey:#"amountSlider"];
I have created about 10-20 UITextViews, but everytime I write something in the simulator, it disappears when exiting the viewcontroller, going back to the "menu" and then clicking back to the viewcontroller with the UITextViews. I really need the text to be saved, but I can't figure out how to do it, despite looking on Youtube etc.
You can have separate save and load method for each uitextview or you can store them in json file. Input : Textfield.text, Section : which textfield do you want to save and load. Then you just call the load method in the ViewDidLoad.
- (void) saveTemporary:(NSString *)input :(NSString *)section
{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults setObject:input forKey:[NSString stringWithFormat:#"textfield_%#",section]];
[[NSUserDefaults standardUserDefaults] synchronize];
}
-(NSString *)loadTemporary :(NSString *)section
{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *loadingString = [defaults objectForKey:[NSString stringWithFormat:#"textfield_%#",section]];
return loadingString;
}
Here is for the json Tutorial :
http://www.raywenderlich.com/5492/working-with-json-in-ios-5
I have an app already in the AppStore that uses NSUserDefaults. Some of the defaults are Default settings that I go ahead and set when the app is first launched, and then the user is allowed to change them later if they wish. So, in my AppDelegate appDidFinishLaunchingWithOptions I put:
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
if (! [defaults boolForKey:#"notFirstRun"]) {
[defaults setBool:YES forKey:#"notFirstRun"];
[defaults setInteger:0 forKey:#"verseKey"];
[defaults synchronize];
}
The issue I am having now is I want to add some more Default settings in the NSUserDefault category, so I want to make it look like this:
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
if (! [defaults boolForKey:#"notFirstRun"]) {
[defaults setBool:YES forKey:#"notFirstRun"];
NSString *smalltitle = #"4";
NSString *smallarticle = #"3";
[defaults setObject:smalltitle forKey:#"Title"];
[defaults setObject:smallarticle forKey:#"Article"];
[defaults setInteger:0 forKey:#"verseKey"];
[defaults synchronize];
}
I know that this will cause an issue for those who have already downloaded the app, and are merely updating it. They will not run that code because the notFirstRun Bool has already been set to YES. Any thoughts on what I should do here?
The proper solution is to not actually populate NSUserDefaults with default values. Instead, use the registerDefaults: method.
At app startup you do:
NSUserDefaults *default = [NSUserDefaults standardUserDefaults];
[defaults registerDefaults:#{
#"Title" : #"4",
#"Article" : #"3",
#"verseKey" : #0
}];
That's it. Call this every time the app is run. These defaults are not actually persisted. The value is only returned if there isn't already an explicit value for the key. You can update these defaults all you want without affecting any existing values.
Make a new notFirstRun Boolean value (i.e. notFirstRunTwo). That will be 'NO' for existing users, too.
I suggest to do the following :
check userdefaults for stored app version if it is equal to the current or not , if not.
store the current app version and do your first launch initialization
the code
`
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *appVersion = [NSString stringWithFormat:#"%#",[[NSBundle mainBundle] objectForInfoDictionaryKey:#"CFBundleShortVersionString"]];
if (! [defaults objectForKey:appVersion ])
{
/// store the current version and then do your first run functions
[defaults setObject:[NSNumber numberWithInt:1] forKey:appVersion];
/// here do your first run
......
}`
Trying to save button state as hidden when navigating off the view controller.
under IBAction
btnonce.hidden = YES;
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults setValue:Act1Button.hidden forKey:#"isHidden"];
Calling it in ViewDidLoad
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
btnonce.hidden = [userDefaults valueForKey:#"isHidden"];
I'm getting the error: Implicit conversion of "BOOL" (aka signed char) to ID is disallowed with ARC
How to rectify this?
For saving the Bool value in NSUserDefaults use this code
[defaults setBool:Act1Button.hidden forKey:#"isHidden"];
For retrieving use this
btnonce.hidden = [userDefaults boolForKey:#"isHidden"];
I set up multiple NSUserDefaults in my app that work for the most part. The NSUserDefaults are called from one ViewController and implemented at another (such as in a game with a level select). This seems to work well, until the user presses the back button on the level select screen. When they try to go back to the level select viewController, the NSUserDefaults are not loaded onto the screen.
Here is my code:
LevelSelectViewController:
- (void)viewDidLoad
{
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
[userDefaults synchronize];
[super viewDidLoad];
}
- (void)Level1DidFinish:(Level1 *)controller
{
[self dismissModalViewControllerAnimated:YES];
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
NSInteger rank = [userDefaults integerForKey:#"levelRank"];
{
if (rank == 1) {
button2.hidden = NO;
}
}
}
Level1ViewController:
{
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
[userDefaults setInteger:1 forKey:#"levelRank"];
}
You need to call [userDefaults synchronize] after setting a value for a key. The automatic synchronization happens quite rarely, so in this case, while one completes a level, the sync won't have yet happened.
So modify your code like this:
Level1ViewController:
{
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
[userDefaults setInteger:1 forKey:#"easyRank"];
[userDefaults synchronize];
}
Your first issue is you are creating an instance of userDefaults, but are not setting any values. So calling synchronize here is actually doing nothing:
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
[userDefaults synchronize];
After you set a your Integer, then you need to call synchronize:
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
[userDefaults setInteger:1 forKey:#"easyRank"];
[userDefaults synchronize];
You're setting values for two different keys. What are you expecting to happen?
Either Level1ViewController needs to set a value for levelRank or LevelSelectViewController needs to read the value for the easyRank key.