In my OS X app, I'm trying to save and retrieve the tag of a radio button. The error occurs on the line marked "<-HERE" in setPreferenceRotor. There is a valid tag coming in.
// PreferenceController.h
extern NSString * const myCellKey;
extern NSString * const myMatrixChangedNotification;
#interface PreferenceController:NSWindowController
{
IBOutlet NSMatrix *matrixRotor;
}
- (IBAction)setRotorTag:(id)sender;
+ (NSInteger)preferenceRotorTag;
+ (void)setPreferenceRotor:(NSInteger)matrixTag;
#end
// PreferenceController.m
NSString * const myMatrixChangedNotification = #"myRotorChanged";
#implementation PreferenceController
- (void)windowDidLoad
{
[super windowDidLoad];
[matrixRotor selectCellWithTag:[PreferenceController preferenceRotorTag]];
}
+ (NSInteger)preferenceRotorTag
{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSData *tagAsData = [defaults objectForKey:myCellKey];
return [NSKeyedUnarchiver unarchiveObjectWithData:tagAsData];
}
+ (void)setPreferenceRotor:(NSInteger)matrixTag
{
//NSInteger mt = matrixTag;
NSData *tagAsData = [NSKeyedArchiver archivedDataWithRootObject:matrixTag]; **//<-HERE**
[[NSUserDefaults standardUserDefaults]setObject:tagAsData forKey:myCellKey];
}
You are passing a primitive (non-object) value, of type NSInteger from variable matrixTag, to a method, archivedDataWithRootObject:, which expects an object reference value. That method happily tries to use the value (which is probably the integer 16, 0x10) as an object reference, and kaboom...
Your thinking looks correct, you know you cannot store non-object values in user defaults, and so you must wrap them as objects first. It is just your way of doing so that is wrong. What you need here is to create an instance of NSNumber from your integer. You could write:
NSNumber *tagAsNumber = [NSNumber numberWithInteger:matrixTag];
[[NSUserDefaults standardUserDefaults] setObject:tagAsNumber forKey:myCellKey];
However this pattern is common enough that a shortcut is provided:
[[NSUserDefaults standardUserDefaults] setInteger:matrixTag forKey:myCellKey];
and this will create the NSNumber object for you. There is also a corresponding integerForKey: method which will unwrap the integer for you when reading.
Related
I use setObject:forKey: to add an object of type Rresource to a NSMutableDictionary named: resourceLib.
Then I immediately look at what's actually in the dictionary and it's OK.
When I try to look at it again in another object's method, the proper key is present but a reference to a string property "url" cases a list of error messages including:
2016-09-28 11:32:42.636 testa[760:16697] -[__NSCFString url]: unrecognized selector sent to instance 0x600000456350
Rresource object is defined as:
#interface Rresource : NSObject
#property (nonatomic,strong) NSString* url;
#property (nonatomic,strong)NSMutableArray* resourceNotesArray;
#property(nonatomic,strong)NSString* name;
#property(nonatomic,strong)NSString* resourceUniqueID;
#property(nonatomic)BOOL isResourceDirty;
This method in a ViewController adds the Rresource to the NSMutableDictionary
-(void)saveResource
{
Rresource* resource = self.currentResource;
Rresource* temp;
if (resource)
{
if ( resource.isResourceDirty)
{
[self.model.resourceLib setObject:resource forKey:resource.resourceUniqueID];
temp = [self.model.resourceLib objectForKey:resource.resourceUniqueID];
}
}
}
Resource and temp contain identical info showing the info was added correctly.
In model's method the following causes the error message described above.
for (Rresource* resource in self.resourceLib)
{
NSString* string = resource.url;
}
where model contains:
#property(nonatomic,strong)NSMutableDictionary* resourceLib;
and :
#implementation Model
- (instancetype)init
{
self = [super init];
if (self)
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES);
self.path = [[paths objectAtIndex:0] stringByAppendingString:#"/Application Support/E2"];
BOOL exists = [[NSFileManager defaultManager] createDirectoryAtPath:self.path withIntermediateDirectories:NO attributes:nil error:nil];
if (!exists)
{
[[NSFileManager defaultManager] createDirectoryAtPath:self.path withIntermediateDirectories:NO attributes:nil error:nil];
}
self.resourceLibPath = [NSString pathWithComponents:#[self.path,#"resources"]];
self.resourceLib = [[NSMutableDictionary alloc]init];
self.noteLibPath = [NSString pathWithComponents:#[self.path, #"notes"]];
self.noteLib = [[NSMutableDictionary alloc]init];
}
return self;
I have found this question difficult to ask clearly even after spending several hours formulating it. I apologize.
I've tried pretty much everything for about a week. I'm stumped.
Any ideas?
Thanks
According to this entry on Enumeration, when you iterate over a dictionary using the fast enumeration syntax, you're iterating over its keys. In the above code sample you're assuming the enumeration happens over its values. What you're effectively doing is casting an NSString object as an Rresource, and sending it a selector only an actual Rresource object can respond to.
This should fix the loop:
for (NSString* key in self.resourceLib)
{
NSString* string = [self.resourceLib objectForKey:key].url;
}
the question is simple but I saw the implementation is fairly awkward!!
I want to post an object e.g. Device object to web api web service
// Initialize Client
AFHTTPClient *client = [[AFHTTPClient alloc] initWithBaseURL:[NSURL URLWithString:#"http://rezawebapi.com"]];
//Indicationg this device is online and sending its dEVICE token to the server
Device *device = [Device new];
device.DeviceToken = [[NSUserDefaults standardUserDefaults] objectForKey:#"devicetoken"];
device.IsOnline = #"True";
//updating current active users of this app in the server
NSDictionary *dictionary = [[NSDictionary alloc]initWithObjectsAndKeys:
device.DeviceToken,#"DeviceToken",
device.IsOnline,#"IsOnline",
nil];
client.parameterEncoding = AFJSONParameterEncoding;
[client postPath:#"/api/iosAppstats" parameters:dictionary success:^(AFHTTPRequestOperation *operation, id responseObject)
{
NSLog(#"%#", responseObject);
// it crashes on the next line because responseObject is NSData
}failure:^(AFHTTPRequestOperation *operation, NSError *error)
{
NSLog(#"%#", error.localizedDescription);
}];
1- is there anyway to send the object without creating an dictionary ?(it is error prone!)
2- when my deviceToken is null the object which it sends to the server is null. but consider here one property deviceToken is null but other properties have their own values! does anyone have any idea?
3- I have defined #property (assign, nonatomic) BOOL IsOnline; but when It creates the dictionary EXEX-BAD-ACCESS rises! how should I define bool value? (I had to define it as NSString. it is not an approved way)
1.
is there anyway to send the object without creating an dictionary ?(it is error prone!)
Your API takes JSON. JSON is just dictionaries, arrays, strings, and numbers. So, no. However, it is not error-prone. Just make sure to only put JSON-compliant objects in your dictionary. Read the NSJSONSerialization Overview for more info.
2.
when my deviceToken is null the object which it sends to the server is null. but consider here one property deviceToken is null but other properties have their own values! does anyone have any idea?
You could add deviceToken conditionally, like so:
NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];
NSString *deviceToken = [[NSUserDefaults standardUserDefaults] objectForKey:#"devicetoken"];
if (deviceToken) {
[dictionary setObject:deviceToken forKey:#"DeviceToken"];
}
3.
I have defined #property (assign, nonatomic) BOOL IsOnline; but when It creates the dictionary EXEX-BAD-ACCESS rises! how should I define bool value? (I had to define it as NSString. it is not an approved way)
Using a BOOL violates this rule from the NSJSONSerialization overview I linked to in #1:
All objects are instances of NSString, NSNumber, NSArray, NSDictionary, or NSNull.
So if your property is a BOOL or other simple numerical type, wrap it in #() to make it an NSNumber:
[dictionary setObject:#(device.IsOnline) forKey:#"DeviceToken"];
This is the same as:
NSNumber *isOnlineNum = [NSNumber numberWithBool:device.isOnline];
[dictionary setObject:isOnlineNum forKey:#"DeviceToken"];
I'm working on my app but i need some help.
I need a 'php-like session' in Objective C (without using connection to the internet)
I've thought about global vars, but my app seems to reset them when reloading the view.
This is my current code
SecondViewController.h
#interface SecondViewController : UIViewController
{
NSString * string;
}
SecondViewController.m
#interface SecondViewController ()
#end
#implementation SecondViewController
- (void)viewDidLoad
{
[super viewDidLoad];
if (! [string isEqualToString:#"Hello"])
{
NSLog(#"Hello");
string = #"Hello";
}
else
{
NSLog(#"Bye");
}
}
#end
But everytime I reload SecondViewController the 'string' is reseted to its default value.
I'm looking for something that we use in php (a.e. $_SESSION['string'] = 'hello')
It could be helpful to you . It stores the values until unless delete the app from your device .
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
// saving an NSString
[prefs setObject:#"TextToSave" forKey:#"keyToLookupString"];
// saving an NSInteger
[prefs setInteger:42 forKey:#"integerKey"];
// saving a Double
[prefs setDouble:3.1415 forKey:#"doubleKey"];
// saving a Float
[prefs setFloat:1.2345678 forKey:#"floatKey"];
// This is suggested to synch prefs, but is not needed (I didn't put it in my tut)
[prefs synchronize];
**Retrieving**
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
// getting an NSString
NSString *myString = [prefs stringForKey:#"keyToLookupString"];
// getting an NSInteger
NSInteger myInt = [prefs integerForKey:#"integerKey"];
// getting an Float
float myFloat = [prefs floatForKey:#"floatKey"];
I am using this in a UINavigation environment.
I have customClassA. It inherits customClassB and one of its object is a NSMutableDictionary.
I alloc and init customClassA in a viewController, then for adding data, I am pushing a new viewController into the stack. The addNewDataViewController sends the newly added data, a customClassB object back by its delegate. Everything works fine so far.
customClassA has to store the returned object (customClassB) into its NSMutableDictionary object with a key (an NSString created from NSDate).
I get "mutating method sent to immutable object" error and can't think of any solution.
Any help is appreciated.
Thanks.
===========================
interface customClassA : NSObject
{
NSDate date;
NSArray *array; // will contain only NSString objects
}
// and the rest as customary
...
#import "customClassA.h"
interface customClassB : NSObject
{
NSString *title;
NSMutableDictionary *data; // will contain values of customClassA with keys of NSString
}
// and the rest as customary
...
#import "customClassB"
#interface firstViewController : UITableViewController <SecondViewControllerDelegate>
- (void)viewDidLoad
{
self.customClassB_Object = [customClassB alloc] init];
// and the rest...
}
- (void)secondViewControllerDidSaveData:(customClassA *)aData
{
[self.customClassB_Object.data setObject:aData forKey:[NSString stringWithFormat:#"%#", aData.date]];
// update tableView
}
Make sure you are initializing the NSMutableDictionary with something like
NSMutableDictionary *myDictionary = [[NSMutableDictionary alloc] init];
It would appear that your NSMutableDictionary is getting created with an NSDictionary instance instead of a NSMutableDictionary
Althoguh I added the following code to customClassB implementation, it still didn't work.
#implementation customClassB
- (id)init
{
self = [super init];
if (self)
self.data = [NSMutableDictionary alloc] init];
return self;
}
so I added two custom methods to my customClassB implementation, as well as in the header file:
- (void)appendData:(customClassA *)aData;
- (void)removeDataWithKey:(NSString *)aKey;
and instead of manipulating the data dicionary of customClassB in my viewController, I simply call that method and pass the data object to the class and it did the trick.
I have the problem that I can't get the Data from one of my classes to the other...
To do this I created this method in the class I am initializing (angebotPage):
- (id) initWithDictionary:(NSDictionary *)dictionary
{
self = [super init];
if (self) {
dict = [dictionary retain];
}
return self;
}
The call from the other class looks like this:
angebotPage *page;
angebotPDF = [[PDFDocument alloc] init];
page = [[angebotPage alloc] initWithDictionary:dictionary];
The Error I get is EXC_BAD_ACCESS in the line where I do:
dict = [dictionary retain];
But why? I need to retain it cause I will use it for the next program steps.. But without retaining I can't use it (EXC_BAD_ACCESS comes elsewhere...)
I recommend that you use a property for dict instead.
#property (retain) NSDictionary *dict;
And then assign the dictionary with self.dict = dictionary. This is assuming all the objects in dictionary are correctly retained in the first place. Try with an empty dictionary if in doubt.