I have this line of code:
NSString *dateString = [self.dates objectAtIndex:row];
that gets set when a user selects a row in a picker. I'd like to have this code available everywhere and not just in the picker select area. Other wise I get a "dateString" is undeclared error message of course.
how would i go about doing this?
thanks for any help.
Why don't you use the singleton design pattern ? To me, it seems to be a cleaner solution that solutions posted above.
VariableStore.m
#import "VariableStore.h"
#implementation VariableStore
#synthesize dateString;
+ (VariableStore *)sharedInstance
{
static VariableStore *myInstance = nil;
if (nil == myInstance)
myInstance = [[[self class] alloc] init];
return myInstance;
}
#end
VariableStore.h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#interface VariableStore : NSObject
{
NSString *dateString;
}
+ (VariableStore *)sharedInstance;
#property (nonatomic, retain) NSString *dateString;
#end
AnyClassWhereYouWantToUseYourVariable.h
#import "VariableStore.h"
AnyClassWhereYouWantToUseYourVariable.m
NSLog("dateString = %#", [VariableStore sharedInstance].dateString);
A simple, but not very elegant solution is to use NSUserDefaults.
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
// saving an NSString
[prefs setObject:#"TextToSave" forKey:#"keyToLookupString"];
[prefs synchronize];
// getting an NSString
NSString *myString = [prefs stringForKey:#"keyToLookupString"];
Define as a global variable in your interface file(.h) file. If you want to use in other class as well make the property and synthesize it.
Use this code. You can save the entire string.
Just create NSString object of
in (YourDelegare.h) file
NSString * dateString;
in (YourDelegare.m) file
-(void) saveMyState
{
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
[prefs setObject:dateString forKey:#"dateString"];
[prefs synchronize];
}
- (void) retrieveMyState
{
//Retrieving
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
dateString = [prefs stringForKey:#"dateString"];
}
just call these methods wherever required.
Or you can declare that variable in your delegate file.
In yourdelegate.h:
NSString *yourString;
#property (nonatomic, retain) NSString *yourString;
In yourdelegate.m:
#synthesize yourString;
In viewcontrolller.h:
yourdelegate *appDelegate;
In viewcontrolller.m:
appDelegate = [[UIApplication sharedApplication] delegate]; // in viewDidLoad
appDelegate.yourString = [self.dates objectAtIndex:row]; // where ever you need
And, like magic, it's a global variable now.
Related
I am developing a game,in that i want to add the points continuously,for this i used plist but whenever the screen is disappear and starts then plist starts again.what to do?
Thanks in Advance.
To add more info to Ahmed's answer you should implement in your AppDelegate.m three methods like this:
AppDelegate.h
NSNumber *gamescore;
#property(nonatomic, strong) NSNumber *gamescore;
#define UIAppDelegate \
((AppDelegate *)[UIApplication sharedApplication].delegate)
AppDelegate.m
#synthesize gamescore;
- (BOOL) checkFirstRun {
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSNumber *defaultcheck;
defaultcheck = [defaults objectForKey:#"GameScore"];
if (defaultcheck==nil) {
return TRUE;
} else {
return FALSE;
}
}
- (void) storeGlobalVars {
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults setObject:gamescore forKey:#"GameScore"];
[defaults synchronize];
}
- (void) readGlobalVars {
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
gamescore = [defaults objectForKey:#"GameScore"];
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
// ...
if ([self checkFirstRun]) {
// first run, lets create basic default values
gamescore = [NSNumber numberWithInt:0];
[self storeGlobalVars];
} else {
[self readGlobalVars];
}
// ...
Later in your application, after importing AppDelegate.h you can use the UIAppDelegate.gamescore to access the AppDelegate's property.
And you have to remember that gamescore is an NSNumber object, you have to manipulate it using NSNumber's numberWithInt and/or intValue.
The CheckFirstRun is needed because your user's device at application first run doesn't contain the default plist and the initial values, you have to create an initial set.
You can make AppDelegate variables and store it in them. There scope remains in the complete application until the application closes.
In AppDelegate.h
for example
NSString *string;
#property(nonatomic, strong) NSString *string;
In AppDelegate.m
#synthesize string;
in applicationDidFinishLaunchingWithOptions
string = #"";
And then is your classes
add #import "AppDelegate.h"
then in your code
((AppDelegate *)[UIApplication SharedApplication].Delegate).string = #"1";
I have this method to save a mutable array named myWallet that contains instances of the Class Card.
- (void)saveMyWallet
{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults setObject:[NSKeyedArchiver archivedDataWithRootObject:self.myWallet] forKey:#"myWalletArray"];
[defaults synchronize];
}
The Card Class that I have has three instance variables: name, pin, and points. So far, saving new instances of the Card in UserDefaults is ok. I would just like to know some suggestions on how can I overwrite the value of points because as I proceed in the computation of points, I want to update it.
Here is my Card Class
Card.h
#import <Foundation/Foundation.h>
#interface Card : NSObject <NSCoding>
#property (nonatomic, strong) NSString *name;
#property (nonatomic, strong) NSString *pin;
#property (nonatomic, strong) NSNumber *points;
#property (nonatomic, strong) NSMutableArray *pointsToDeduct;
- (double) subtractPoints: (double) requiredPoints;
- (void) encodeWithCoder:(NSCoder *)coder;
- (id) initWithCoder: (NSCoder *)coder;
#end
Card.m
#import "Card.h"
#implementation Card
#synthesize name = _name;
#synthesize pin = _pin;
#synthesize points = _points;
#synthesize pointsToDeduct = _pointsToDeduct;
- (id)initWithCoder:(NSCoder *)coder
{
self = [[Card alloc] init];
if(self != nil) {
self.name = [coder decodeObjectForKey:#"name"];
self.pin = [coder decodeObjectForKey:#"pin"];
self.points = [coder decodeObjectForKey:#"points"];
}
return self;
}
- (void)encodeWithCoder:(NSCoder *)coder
{
[coder encodeObject:self.name forKey:#"name"];
[coder encodeObject:self.pin forKey:#"pin"];
[coder encodeObject:self.points forKey:#"points"];
}
- (double) subtractPoints:(double) requiredPoints
{
double latestPoints;
latestPoints = ([self.points doubleValue] - requiredPoints);
return latestPoints;
}
#end
And lastly, here is the delegate method by which the new value of the points (named resultingPoints) should come from.
- (void)perksDetailsViewController:(PerksDetailsViewController *)sender didPassRequiredPoints:(NSNumber *)requiredPoints withCard:(Card *)selectedCard
{
double perksPoints = [requiredPoints doubleValue];
self.resultingPoints = [NSNumber numberWithDouble:[selectedCard subtractPoints:perksPoints] ];
NSLog(#"points remaining %#", self.resultingPoints);
}
Bombard me with suggestions :) Thanks in advance!
From what I see, you actually save your object as NSData, so the logical approach is to get it back from the user defaults, unarchive it, update the properties, archive it and save it back to the user defaults.
Retrive the data from NSUserDefaults into runtime,Delete previous object for key and write back updated value.
I have a NSString that is taken from a UITextField in a ViewController. Every of my other ViewController will use this NSString as well. How can I pass this NSString to others ViewControllers?
You want to have a property in each of your controllers
#interface MyViewController : UIViewController{
NSString *title;
}
#property (retain) NSString *title;
#end;
#implementation MyViewController
#synthesize title;
#end;
Use it like:
MyViewController *myVC = [[MyViewController alloc] initWithFrame:...];
myVC.title = #"hello world";
You should be familiar with Memory Management
Create a class for sharing your common objects. Retrieve it using a static method, then read and write to its properties.
#interface Store : NSObject {
NSString* myString;
}
#property (nonatomic, retain) NSString* myString;
+ (Store *) sharedStore;
#end
and
#implementation Store
#synthesize myString;
static Store *sharedStore = nil;
// Store* myStore = [Store sharedStore];
+ (Store *) sharedStore {
#synchronized(self){
if (sharedStore == nil){
sharedStore = [[self alloc] init];
}
}
return sharedStore;
}
// your init method if you need one
#end
in other words, write:
Store* myStore = [Store sharedStore];
myStore.myString = #"myValue";
and read (in another view controller):
Store* myStore = [Store sharedStore];
myTextField.text = myStore.myString;
If the string remains the same, and never changes, you could make a file named defines.h (without the .m file) and have this line:
#define kMyString #"Some text"
Then wherever you need the string, just import the defines file and use the constant.
#import "defines.h"
Much simpler than making custom classes.
EDIT:
Didn't see you needed to grab from the text field.
In that case, you could have it stored as property of your app delegate class and get it from there. The delegate can be accessed from anywhere in your app.
This is really twisting my mind… I'm trying to access an NSMutableArray in an IBAction which I defined in viewDidLoad. Unfortunately I keep getting a EXC_BAD_ACCESS.
I'm new to all this so I'd really appreciate some insight in what I'm doing wrong.
Below find the corresponding code excerpts.
CounterViewController.h:
#interface CounterViewController : UIViewController{
NSMutableArray *countHistoryArray;
}
#property(nonatomic, retain) NSMutableArray *countHistoryArray;
CounterViewController.m:
#implementation CounterViewController
#synthesize countHistoryArray;
- (void)viewDidLoad {
[super viewDidLoad];
//Fill array with some dummy data
self.countHistoryArray = [[NSMutableArray alloc] init];
NSDate *now = [[[NSDate alloc] init] autorelease];
CurrentCount *historicCount = [[[CurrentCount alloc]
initWithCount:[NSNumber numberWithInteger:22]
description:#"Testcount"
dateAndTime:now] autorelease];
[self.countHistoryArray addObject: historicCount];
//Do some logging - everything is working fine here!
NSLog(#"%#", [self.countHistoryArray description]);
}
//Later on we click on a button and want to use the array
- (IBAction)doSomeStuff {
//Let's look at the array again - and now it crashes with EXC_BAD_ACCESS
NSLog(#"%#", [self.countHistoryArray description]);
}
Thanks a lot!
Manuel
EDIT Additional code as asked for by #jamapag
CurrentCount.h
#import <Foundation/Foundation.h>
#interface CurrentCount : NSObject {
NSNumber *counterLevel;
NSString *description;
NSDate *dateAndTime;
}
- (id)initWithCount:(NSNumber *)newCounterLevel description:(NSString *)newDescription dateAndTime:(NSDate *)newDateAndTime;
#property(nonatomic, copy) NSNumber *counterLevel;
#property(nonatomic, copy) NSString *description;
#property(nonatomic, copy) NSDate *dateAndTime;
#end
CurrentCount.m
#import "CurrentCount.h"
#implementation CurrentCount
#synthesize counterLevel;
#synthesize description;
#synthesize dateAndTime;
- (id)initWithCount:(NSNumber *)newCounterLevel description:(NSString *)newDescription dateAndTime:(NSDate *)newDateAndTime{
self = [super init];
if(nil != self){
self.counterLevel = newCounterLevel;
self.description = newDescription;
self.dateAndTime = newDateAndTime;
}
return self;
}
-(void) dealloc{
self.counterLevel = nil;
self.description = nil;
self.dateAndTime = nil;
[super dealloc];
}
#end
Are you sure that your code actually looks like this?
- (IBAction)doSomeStuff {
//Let's look at the array again - and now it crashes with EXC_BAD_ACCESS
NSLog(#"%#", [self.countHistoryArray description]);
}
Your question title says "NSMutableArray count causes EXC_BAD_ACCESS" - if that line of code actually says NSLog(#"%#", [self.countHistoryArray count]);, you'll almost certainly get a crash, since NSLog will attempt to treat a primitive type (the type returned by -[NSArray count]) as an object. In order to use -[NSArray count] in NSLog, use %u instead of %#:
- (IBAction)doSomeStuff {
// This time it should work!
NSLog(#"Array Count = %u", [self.countHistoryArray count]);
}
Remove autorelease from:
currentCount *historicCount = [[[CurrentCount alloc]
initWithCount:[NSNumber numberWithInteger:22]
description:#"Testcount"
dateAndTime:now] autorelease];
It looks like you are accidentally releasing countHistoryArray somewhere. Try removing all calls to it except for those two you showed. Additionally you can try enabling zombies to debug the problem.
Oh and by the way you probably don't really want a public NSMutableArray property and if you do you probably want it to be copy, not retain. Otherwise incapsulation kinda goes down the drain.
I know this question has already been solved and accepted but its for others who are or will face this issue.
I was facing the same issue, I tried all solutions but no solution worked for me. The project I am working on is NON-ARC.
I tried and made a simple change in property
Previously my property for NSMUTABLEARRAY was
#property (nonatomic, assign) NSMutableArray * dataArray;
I changed it to:
#property (nonatomic, retain) NSMutableArray * dataArray;
Changed it from ASSIGN to RETAIN
And it solved my problem
I am having an issue in converting a NSObject into NSData. I have a class which inherits NSObject.
When i tried to convert the object of that particular class into NSData as follows :
NSData *dataOnObject = [NSKeyedArchiver archivedDataWithRootObject:classObject];
but it gives out exception stating that -[classObject encodeWithCoder:]: unrecognized selector sent to instance ..
I have also added the object to a newly created array as
NSMutableArray *wrapperedData = [NSMutableArray arrayWithObject: classObject];
NSData *dataOnObject = [NSKeyedArchiver archivedDataWithRootObject:value];
But still , its giving out exception.
So I need to extract the bytes from the object classObject.
Any help would be greatly appreciated ...
awaiting for your reply ...
You must implement for your own object such as:
- (void)encodeWithCoder:(NSCoder *)aCoder
{
[aCoder encodeObject:self.name forKey:#"name"];
[aCoder encodeInt:self.age forKey:#"age"];
[aCoder encodeObject:self.email forKey:#"email"];
[aCoder encodeObject:self.password forKey:#"password"];
}
BOOL success = [NSKeyedArchiver archiveRootObject:person toFile:archiveFilePath];
and:
- (id)initWithCoder:(NSCoder *)aDecoder
{
if (self = [super init]) {
self.name = [aDecoder decodeObjectForKey:#"name"];
self.age = [aDecoder decodeIntForKey:#"age"];
self.email = [aDecoder decodeObjectForKey:#"email"];
self.password = [aDecoder decodeObjectForKey:#"password"];
}
return self;
}
Person *unarchivePerson = [NSKeyedUnarchiver unarchiveObjectWithFile:archiveFilePath];
You need to implement encodeWithCoder: on your custom class, serializing all of its attributes using the NSCoder passed into it. If its attributes include any more custom classes, they'll need encodeWithCoder: implementing too.
Instead of
NSData *dataOnObject = [NSKeyedArchiver archivedDataWithRootObject:classObject];
it should be
NSData *dataOnObject = [[NSUserDefaults standardUserDefaults] objectForKey:#"someKey"];
But that's just for reading data in that's already been saved. If you want to save an object as NSData then you have this:
[[NSUserDefaults standardUserDefaults] setObject:[NSKeyedArchiver archivedDataWithRootObject:classObject] forKey:#"someKey"];
But that's not all. Your classObject has to implement the NSCoding protocol and have the two methods encodeWithCoder: and initWithCoder: since it's not an NS object in order for it to work.
you can only archive objects that support the NSCoding protocol
You can convert any object to NSData with the NSCoding protocol.
You can find sample code to do this here:
http://samsoff.es/posts/archiving-objective-c-objects-with-nscoding
This is a example of custom object converted to NSData (so it can be then saved into user defaults)
Create the following files:
Catalog.h
#interface Catalog : NSObject
#property (nonatomic, assign) int pk;
#property (nonatomic, copy) NSString *catalogName;
#property (nonatomic, copy) NSString *catalogDescription;
#property (nonatomic, assign) int catalogEdition;
#property (nonatomic, assign) int catalogTotalPages;
- (void)encodeWithCoder:(NSCoder *)aCoder;
- (id)initWithCoder:(NSCoder *)aDecoder;
#end
Catalog.m
#import <Foundation/Foundation.h>
#import "Catalog.h"
#implementation Catalog
- (void)encodeWithCoder:(NSCoder *)aCoder {
[aCoder encodeObject:self.catalogName forKey:#"catalogName"];
[aCoder encodeObject:self.catalogDescription forKey:#"catalogDescription"];
[aCoder encodeInt:self.catalogEdition forKey:#"catalogEdition"];
[aCoder encodeInt:self.catalogTotalPages forKey:#"catalogTotalPages"];
}
- (id)initWithCoder:(NSCoder *)aDecoder
{
if (self = [super init]) {
self.catalogName = [aDecoder decodeObjectForKey:#"catalogName"];
self.catalogDescription = [aDecoder decodeObjectForKey:#"catalogDescription"];
self.catalogEdition = [aDecoder decodeIntForKey:#"catalogEdition"];
self.catalogTotalPages = [aDecoder decodeIntForKey:#"catalogTotalPages"];
}
return self;
}
#end
Finally in your controller include header files
#import "Catalog.h"
And add this code to use your object (in this case im saving into user defaults)
Catalog *catalog = [[Catalog alloc] init];
catalog.catalogName = #"catalogName";
catalog.catalogDescription = #"catalogName";
catalog.catalogEdition = 1;
NOTE: in this line of code is where the actual data passing is taking place
//archiving object to nsdata
NSData *encodedObject = [NSKeyedArchiver archivedDataWithRootObject:catalog];
[[NSUserDefaults standardUserDefaults] setObject:encodedObject forKey:#"keyName"];
[[NSUserDefaults standardUserDefaults] synchronize];
In case you want to get your object back from NSData
NSData *nsData = [[NSUserDefaults standardUserDefaults] objectForKey:#"keyName"];
//unarchiving object to nsdata
Catalog *selectedCatalog = [NSKeyedUnarchiver unarchiveObjectWithData: nsData];
Hope this helps!