How can I make my application display something only when they first launch the application for the first time. Example: They open up my app, an alert comes up, saying something like, "Do you want to play the tutorial?" Then, if they close the app, then re-open it, it won't show up again.
Thanks
I'd recommend using NSUserDefaults:
- (void)openOneTime
{
NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
static const NSString* kKey = #"One Time Key";
NSObject* keyValue = [defaults objectForKey:kKey];
if (keyValue == nil)
{
[self doMyOneTimeThing]; // pop a dialog, etc...
}
// Adds an object for our key which will get found the next time around,
// bypassing the above code block. The type and value of the object is
// not important; what matters more is that an object exists for that
// key at all.
[defaults setBool:YES forKey:kKey];
}
More tips on storing data persistently:
Method 1: Use the global user preferences system. You can do this, but it might be considered slightly hacky because it is designed to store user preferences, and I think this is a gray area, since the user doesn't have explicit control here. In any case, check out the docs for NSUserDefaults to find out how to do that.
Method 2: Write to a file whose existence indicates whether or not the tutorial has been viewed. You can easily create a file with an NSData object by calling its writeToFile:atomically: method. Later, you can use the NSFileManager class to check if that file exists or not.
Sample code:
- (NSString*) filename {
NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES);
NSString* documentsDirectory = [paths objectAtIndex:0];
return [documentsDirectory stringByAppendingPathComponent:#"notFirstTime"];
}
- (void) setNotFirstTime {
NSData* data = [[[NSData alloc] init] autorelease];
[data writeToFile:[self filename] atomically:YES];
}
- (BOOL) isNotFirstTime {
return [[NSFileManager defaultManager] fileExistsAtPath:[self filename]];
}
You could store in your property store a boolean value saying whether it's the first time or not, then check that on application start.
Related
I am trying to access the nsstring data out side the function and also outside the class.
How can I access useridStr outside the function and class? This is my code:
-(id)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSString *loginStatus = [[NSString alloc] initWithBytes:[webData mutableBytes]
length:[webData length] encoding:NSUTF8StringEncoding];
NSDictionary *loginDict = [[loginStatus JSONValue] objectForKey:#"UserDetails"];
NSArray *userId = [loginDict valueForKey: #"userid"];
NSString *useridStr = [userId lastObject];
NSLog(#"--------------....%#", useridStr);
}
NSUserDefaults *pre = [NSUserDefaults standardUserDefaults];
[pre setObject:useridStr forKey:#"useridStr"];
where you want to need string:
NSUserDefaults *pre =[NSUserDefaults standardUserDefaults];
NSString * useridStr =[pre stringForKey:#"useridStr"];
OR
In .h file of anotherView
-(id)initUserInfo:(NSString *)string;
In .m file of anotherView
-(id)initUserInfo:(NSString *)string{
if (self = [super initWithNibName:#"nextView" bundle:nil]) {
useridStr=string
}
return self;
}
In .m File of firstView
-(IBAction)btnNext_TouchUpInside:(id)sender{
nextView *second =[[nextView alloc]initUserInfo:useridStr];
[self presentModalViewController:second animated:NO];
}
What Piyush suggested is also correct. But there is also another way to achieve it.
As he suggested NSUserDefaults to save data you should keep in mind that NSUserDefaults is generally used to save data like preferences which you want it to be stored even after Application is closed by user and you want those data again when you start your application.
So if you want to save data like preferences go for NSUserDefaults. If you want your data to be available throughout your application while its running and you do not need to save them like preferences I would recommend you declare that object globally in Appdelegate file and access them whenever you need. You should not store them as NSUserDefaults because as Apple document says whatever you store in NSUserDefaults it will be saved in user's default database. So that will consume memory of your device. So in short saving everything to NSUserDefaults won't be a good idea if we consider memory managent concepts.
I've created a small class that loads dictionary items from a plist file. The getSettingForKey method works the first time I call the static method, however after a few more calls the dictionary throws a SIGABRT exception for a call with the same key that worked on a previous call. Any ideas?
static NSDictionary *dictionary = nil;
static NSLock *dictionaryLock;
#implementation ApplicationSettingsHelper
+ (void) initialize
{
dictionaryLock = [[NSLock alloc] init];
// Read plist from application bundle.
NSString *path = [[NSBundle mainBundle] bundlePath];
NSString *finalPath = [path stringByAppendingPathComponent:#"Xxxx.plist"];
dictionary = [NSDictionary dictionaryWithContentsOfFile:finalPath];
// dump the contents of the dictionary to the console.
for(id key in dictionary)
{
NSLog(#"bundle: key=%#, value=%#", key, [dictionary objectForKey:key]);
}
}
+ (NSDictionary *)dictionaryItems
{
[dictionaryLock lock];
if (dictionary == nil)
{
[self initialize];
}
[dictionaryLock unlock];
return dictionary;
}
+(id)getSettingForKey:(NSString *)key
{
return [[self dictionaryItems] objectForKey:key];
}
#end
Moshe - I've taken your suggestion and updated to use NSUserDefaults instead:
+ (void)load
{
// Load the default values for the user defaults
NSString* pathToUserDefaultsValues = [[NSBundle mainBundle]
pathForResource:#"Xxxx"
ofType:#"plist"];
NSDictionary* userDefaultsValues = [NSDictionary dictionaryWithContentsOfFile:pathToUserDefaultsValues];
// Set them in the standard user defaults
[[NSUserDefaults standardUserDefaults] registerDefaults:userDefaultsValues];
}
+ (id)getSettingForKey:(NSString *)key
{
return [[NSUserDefaults standardUserDefaults] valueForKey:key];
}
Your dictionary has probably been deallocated, causing an invalid memory access. When you create a dictionary using the dictionaryWithContentsOfFile: method, it is autoreleased, which means it will automatically be released in the future. Since you never retain the dictionary, that release will cause the dictionary to be deallocated.
Also, most of your dictionaryItems method is useless.
[dictionaryLock lock];
if (dictionary == nil) {
[self initialize];
}
[dictionaryLock unlock];
The +initialize method is automatically called by the runtime before any other method is called on your class, unless you have a +load method. Since the runtime will call it for you and it will attempt to create the dictionary, the dictionary can only be nil in the dictionaryItems method if there wasn't enough memory to create it, in which case it will fail again. Also, if you don't use the lock anywhere else, it is unnecessary also, since removing that check would cause it to be locked and immediately unlocked. Therefore, you can remove the lock and change your dictionaryItems method to simply:
+ (NSDictionary *)dictionaryItems {
return dictionary;
}
In addition to #ughoavgfhw's answer, you are also initializing dictionaryLock after you are locking it. Unless you are initializing dictionaryLock somewhere else, I'm surprised your code is getting as far as it is.
Edit: I see from #ughoavgfhw's edit that +initialize is called before anything else, so your lock is initialized there.
In my app I need to save a double value (high score) and String (player name) what should i use to get this.
any idea will be great.
Thank you
If this is all you're saving then NSUserDefaults should be fine
// To store
[[NSUserDefaults standardUserDefaults] setObject:name forKey:#"name"];
[[NSUserDefaults standardUserDefaults] setDouble:score forKey:#"score"];
// To read back in
NSString *name = [[NSUserDefaults standardUserDefualts] objectForKey:#"name"];
double score = [[NSUserDefaults standardUserDefaults] doubleForKey:#"score"];
// Don't forget that your name is autoreleased - if you want to keep it, set it to a retained
// property or retain it yourself :)
As deanWombourne said, you can use NSUserDefaults to store these data but it isn't very secure. If you don't want to store this data "in the air", you can take a look to SFHFKeychainUtils by Buzz Andersen to store them in the iPhone Keychain.
First of all, copy SFHFKeychainUtils files to your project. Click on the SFHFKeychainUtils.m and click on Get Info. Go to Target tab and check if the box near your target is checked. If not, check it. Control-click on your Framework folder and select Add Existing Framework. Find Security.framework and add it to your project. Check also that this framework is added to your target by doing the same procedure done for SFHFKeychainUtils.m. Now open you implementation file on where you want to use this code and add on the top #import "SFHFKeychainUtils.h".
This is a little example on how to use this code:
// to store your data
NSError *error = nil;
[SFHFKeychainUtils storeUsername:kName andPassword:name forServiceName:kStoredName updateExisting:YES error:&error];
[SFHFKeychainUtils storeUsername:kScore andPassword:score forServiceName:kStoredScore updateExisting:YES error:&error];
// to get them back
NSString *name = [SFHFKeychainUtils getPasswordForUsername:kName andServiceName:kScoredName error:&error];
double score = [SFHFKeychainUtils getPasswordForUsername:kScore andServiceName:kScoredScore error:&error];
// kName, kScore, kStoredName, kStoredScore are defined key but you can use also strings with #"your string here".
// It is important that when you store and get back a value, username and serviceName must be the same.
I've been developing an iPhone app for the last few months. Recently I wanted to up performance and cache a few of the images that are used in the UI. The images are downloaded randomly from the web by the user so I can't add specific images to the project. I'm also already using NSUserDefaults to save other info within the app.
So now I'm attempting to save a dictionary of UIImages to my NSUserDefaults object and get...
-[UIImage encodeWithCoder:]: unrecognized selector sent to instance
I then decided to subclass UIImage with a class named UISaveableImage and implement NSCoding. So now I'm at...
#implementation UISaveableImage
-(void)encodeWithCoder:(NSCoder *)encoder
{
[encoder encodeObject:super forKey:#"image"];
}
-(id)initWithCoder:(NSCoder *)decoder
{
if (self=[super init]){
super = [decoder decodeObjectForKey:#"image"];
}
return self;
}
#end
which isn't any better than where I started. If I was able to convert an UIImage to NSData I would be good, but all I can find are function like UIImagePNGRepresentation which require me to know what type of image this was. Something that UIImage doesn't allow me to do. Thoughts? I feel like I might have wandered down the wrong path...
You don't want to store images in NSUserDefaults. They're big blobs of data, and NSUserDefaults is stored as a plist; you want to write small bits of info to it.
You should write the images to disk, and then store the filenames to defaults:
NSString *filename = myImageFilename;
[UIImagePNGRepresentation(image) writeToFile: myImageFilename atomically];
[[NSUserDefaults standardDefaults] setObject: myImageFilename forKey: #"lastImageFilename"];
Stumbling upon this a year later. I would add (in case someone else stumbles here as well) that you should store the images in the cache directory and avoid iTunes trying to back them up.
- (NSString *)pathForSearchPath:(NSSearchPathDirectory)searchPath {
NSArray *paths = NSSearchPathForDirectoriesInDomains(searchPath, NSUserDomainMask, YES);
NSString *directoryPath = [paths objectAtIndex:0];
return directoryPath;
}
- (NSString *)cacheDirectoryPath {
return [self pathForSearchPath:NSCachesDirectory];
}
I've got some settings saved in my Settings.bundle, and I try to use them in application:didFinishLaunchingWithOptions, but on a first run on the simulator accessing objects by key always returns nil (or 0 in the case of ints). Once I go to the settings screen and then exit, they work fine for every run thereafter.
What's going on? Isn't the point of using default values in the Settings.bundle to be able to use them without requiring the user to enter them first?
If I got your question right, in your app delegate's - (void)applicationDidFinishLaunching:(UIApplication *)application, set the default values for your settings by calling
registerDefaults:dictionaryWithYourDefaultValues
on [NSUserDefaults standardUserDefaults]
- (void)applicationDidFinishLaunching:(UIApplication *)application {
NSUserDefaults *ud = [NSUserDefaults standardUserDefaults];
NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:3], #"SomeSettingKey",
#"Some string value", #"SomeOtherSettingKey",
nil];
[ud registerDefaults:dict];
}
These values will only by used if those settings haven't been set or changed by previous executions of your application.
As coneybeare said "You should detect if it is the first load, then store all your defaults initially."
On applicationDidFinishLaunching try to set default value in your preference.
Here is the sample:
NSUserDefaults *defaults =[NSUserDefaults standardUserDefaults];
if([defaults objectForKey:#"YOUR_KEY"] == nil)
{
[defaults setValue:#"KEY_VALUE" forKey:#"YOUR_KEY"];
}
When application will run second time it will come with KEY_VALUE for YOUR_KEY.
Thanks,
Jim.
Isn't the point of using default
values in the Settings.bundle to be
able to use them without requiring the
user to enter them first?
No. The point of the settings bundle is to give the user a place to edit all 3rd Party app settings in a convenient place. Whether or not this centralization is really a good idea is a User Experience issue that is off topic.
To answer your question, you should detect if it is the first load, then store all your defaults initially.
And while we are on the subject, I would also check out In App Settings Kit as it provides your app with a simple way to display your app settings in both places (in-app and Settings.app) with minimal code.
The values in the Settings.bundle are intended for the Settings app to able to fill in default values for your app. They are not used by your own app.
But you can set defaults yourself with the registerDefaults: method of NSUserDefaults. This will not actually set them on disk but just give "defaults for the defaults": they are used when no value has been set by the user yet.
Setting registerDefaults: must be done before any use of the default values. The "applicationDidFinishLaunching:" method that others suggested for this, is too late in most cases. By the time "applicationDidFinishLaunching:" is called, your views have already been loaded from the nib files, and their "viewDidLoad:" methods have been called. And they may typically read user defaults.
To guarantee that the defaults are set before first use, I use the following utility class, which loads the values from the Root.plist file and sets them with "registerDefaults:". You use this class to read user defaults instead of "[NSUserDefaults standardUserDefaults]". Use "[Settings get]" instead.
As a bonus, it also contains a registration method for user default change notifications, because I always forget how that is done.
#import "Settings.h"
#implementation Settings
static bool initialized = NO;
+ (void) setDefaults
{
NSString *bundlePath = [[NSBundle mainBundle] bundlePath];
NSString *settingsBundlePath = [bundlePath stringByAppendingPathComponent:#"Settings.bundle"];
NSBundle *settingsBundle = [NSBundle bundleWithPath:settingsBundlePath];
NSString *settingsPath = [settingsBundle pathForResource:#"Root" ofType:#"plist"];
NSDictionary *settingsDict = [NSDictionary dictionaryWithContentsOfFile:settingsPath];
NSArray *prefSpecifierArray = [settingsDict objectForKey:#"PreferenceSpecifiers"];
NSMutableDictionary *appDefaults = [[NSMutableDictionary alloc] init];
for (NSDictionary *prefItem in prefSpecifierArray)
{
NSString *key = [prefItem objectForKey:#"Key"];
if (key != nil) {
id defaultValue = [prefItem objectForKey:#"DefaultValue"];
[appDefaults setObject:defaultValue forKey:key];
}
}
// set them in the standard user defaults
[[NSUserDefaults standardUserDefaults] registerDefaults:appDefaults];
if (![[NSUserDefaults standardUserDefaults] synchronize]) {
NSLog(#"Settings setDefaults: Unsuccessful in writing the default settings");
}
}
+ (NSUserDefaults *)get
{
if (!initialized) {
[Settings setDefaults];
initialized = YES;
}
return [NSUserDefaults standardUserDefaults];
}
+ (void) registerForChange:(id)observer selector:(SEL)method
{
[[NSNotificationCenter defaultCenter] addObserver:observer selector:method name:NSUserDefaultsDidChangeNotification object:nil];
}
+ (void) unregisterForChange:(id)observer
{
[[NSNotificationCenter defaultCenter] removeObserver:observer name:NSUserDefaultsDidChangeNotification object:nil];
}