I am facing a very weird issue. I create an object and I add it to a NSMutableArray but when I try to read it after I insert it, some subclasses of the object change to some weird classes like
PINGIFAnimatedImageManager
Here is the code I use to create the object and insert it to the NSMutableArray:
CustomContentGridRow *row = [[CustomContentGridRow alloc]init];
row.child1 = [dataManager getMapLocation]; // This is the MapLocation object that will change to this weird PINGIFAnimatedImageManager
row.useFullWidth=1;
row.index=0;
[arrCustomChilds addObject:row];
This is the CustomContentGridRow class:
#interface CustomContentGridRow : NSObject
#property (nonatomic, assign) MapLocation *child1;
#property (nonatomic, assign) MapLocation *child2;
#property (nonatomic, assign) int useFullWidth;
#property (nonatomic, assign) int index;
#end
So when I put a breakpoint at this line [arrCustomChilds addObject:hotelRow];, when I read the row object I get the expected results. But when I place a breakpoint after the above code to read the arrCustomChilds the class of child1 changes to some weird classes. Also, sometimes it won't change to another class but it will give nil values.
Any idea why this is happening?
You should change property modifier from "assign" to "strong" for class objects. Otherwise undefined behaviour can happen.
In Xcode -> Product -> Scheme - edit Scheme. Check the settings of RUN mode. If it is Release change to Debug.
This will give you the correct values
Change below properties
#property (nonatomic, strong) MapLocation *child1;
#property (nonatomic, strong) MapLocation *child2;
assign to strong
Your interface should be:
#interface CustomContentGridRow : NSObject
#property (nonatomic, strong) MapLocation *child1;
#property (nonatomic, strong) MapLocation *child2;
#property (nonatomic, assign) int useFullWidth;
#property (nonatomic, assign) int index;
#end
the class objects should be strong not assign
Related
if Data is
{ "id": "10", "country": "Germany", "dialCode": 49, "isInEurope": true }
someone using
#interface CountryModel : JSONModel
#property (assign, nonatomic) int id;
#property (strong, nonatomic) NSString* country;
#property (strong, nonatomic) NSString* dialCode;
#property (assign, nonatomic) BOOL isInEurope;
#end
other using
#interface CountryModel : JSONModel
#property (nonatomic) int id;
#property (nonatomic) NSString* country;
#property (nonatomic) NSString* dialCode;
#property (nonatomic) BOOL isInEurope;
#end
Which is better usage?
Both the methods are correct. Declaration of properties depends on your requirement.Properties are used to declare a class’s accessor methods. How can a class access model's data.While declaring property you can then optionally provide set of property attributes that define the storage semantics and other behaviors of the property.When we are defining an object's property as weak/strong we are defining its accessibility to the class.
It depends on how you need to access the data. If you want you object to thread safe,you can define as nonatomic. By defining it as strong/ assign it defines that you own the object.And by defining it as weak you dont own your object. Check this link for more info.
Hope it helps. Happy Coding!!
i successfully integrated core data in my JSQ project, for my JSQMessageData i use NSManagedObject i created called CDChatMessage
#interface CDChatMessage : NSManagedObject < JSQMessageData >
#end
at my JSQMessagesViewController i use NSfetchedresultsController,
it works fine for text messages but i can't figure out how to implement media messages.
JSQMessage.h have a property that represent the Media Data
#property (copy, nonatomic, readonly) id< JSQMessageMediaData > media;
but obviously i cant assassin property of type JSQMessageMediaData to my NSManagedObject,
anyone have a solution for using JSQMessageMediaData with Core Data ?
thanks.
Basically what I've done to solve this kind of issue is this:
Instead of using CoreData object which conforms to JSQMessageData I use something called viewModel.
A ViewModel is basically a normal NSObject which just unwraps all necessary information from the CoreData object and conforms to JSQMessageData protocol - providing text, senderId, and other information (and also media message if necessary)
#interface ChatMessageViewModel : NSObject <JSQMessageData>
#property (nonatomic, strong, readonly) CDChatMessage *chatMessage;
// main properties
#property (nonatomic, copy, readonly) NSString *text;
#property (nonatomic, copy, readonly) NSString *senderId;
#property (nonatomic, copy, readonly) NSString *watcherId;
...
#property (nonatomic, strong, readonly) JSQMessage *mediaMessage;
- (instancetype)initWithChatMessage:(CDChatMessage *)chatMessage;
#end
.m file could look like this:
#interface ChatMessageViewModel ()
#property (nonatomic, strong, readwrite) CDChatMessage *chatMessage;
// main properties
#property (nonatomic, copy, readwrite) NSString *text;
#property (nonatomic, copy, readwrite) NSString *senderId;
#property (nonatomic, copy, readwrite) NSString *watcherId;
...
#property (nonatomic, strong, readwrite) JSQMessage *mediaMessage;
#end
#implementation ChatMessageViewModel
- (instancetype)initWithChatMessage:(CDChatMessage *)chatMessage
if (self = [super init]) {
_chatMessage = chatMessage;
[self unpackViewModel];
}
return self;
}
- (void)unpackViewModel {
self.senderId = self.chatMessage.senderId;
self.text = self.chatMessage.senderId;
self.mediaMessage = [self unpackMediaData];
}
- (JSQMessage *)unpackMediaData {
// Here CDCustomPhotoMediaItem is a subclass of JSQPhotoMediaItem which just lets me create custom look of JSQ media item.
JSQPhotoMediaItem *photoItem = [[CDCustomPhotoMediaItem alloc] init];
return [JSQMessage messageWithSenderId:self.senderId displayName:#"" media:photoItem];
}
After I fetch data using NSFetchResultsController I just take all core data objects and turn them into immutable viewModels.
Then in cellForItemAtIndexPath I just call this:
cell.mediaView = [viewModel.media mediaView];
This approach creates nice immutable wrapper which contains only necessary chunk of information needed by the JSQ chat library. Also, you can easily write tests for such object. If you're using swift, you can use struct for this kind of purpose.
Hope my answer helps. Please ask if you need more detailed answer. ;-)
I have a custom NSObject called MAAssignment. It's basically a data type that has a number of #properties and one custom init method:
#property (nonatomic, strong) NSDate *date;
#property (nonatomic, strong) NSString *assignmentName;
#property (nonatomic, strong) NSNumber *totalPoints;
#property (nonatomic, strong) NSNumber *recievedPoints;
#property (nonatomic, strong) NSNumber *classAverage;
#property (nonatomic, strong) NSNumber *extraCredit;
#property (nonatomic, strong) NSNumber *notGraded;
- (id)initWithDate:(NSString *)date assignmentName:(NSString *)assignmentName totalPoints:(NSNumber *)totalPoints recievedPoints:(NSNumber *)recievedPoints classAverage:(NSString *)classAverage extraCredit:(NSNumber *)extraCredit notGraded:(NSNumber *)notGraded;
I create an instance of it in the viewController, hoping to populate the newly created item with some data... But I can't figure out how to access the variables of the object. I went MAAssignment *assignment = [[MAAssignment alloc] init];, then I tried [assignment setDate] or assignment.date = ddate but none of them seem to work.
Am I misunderstanding how the accessors for objects work?
You should place these variables in h. file
of MAAsignment
I'm not understanding your question very well (where are you declaring this code? What's the full code of your MAAsiignment initialization example?), however I'll try to answer anyway.
Are you sure that the #property declarations are inside the #interface in .h and not inside .m?
The #interface inside .m is a private class extensions, and allows you to declare private properties. To make them available outside, you need to put them inside the header (.h).
Please post more code to let us provide a more exhaustive answer.
What you describe is a data container object. It should work as described:
MAAssignment *anAssignment = [[MAAssignment alloc] init];
anAssignment.date = [NSDate date];
anAssignment.totalPoints = #(10);
NSLog(#"anAssignment.date = %#", anAssignment.date);
NSLog(#"anAssignment.totalPoints = %#", anAssignment.totalPoints);
Should work perfectly. Are you getting any warnings?
I have a CoreData-based app. In Core Data, I have an entity called ZSProduction which creates an NSManagedObject subclass called ZSProductionCD. This is the .h file created.
#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>
#interface ZSProductionCD : NSManagedObject
#property (nonatomic, retain) NSNumber * appVersion;
#property (nonatomic, retain) id highlightColour;
#property (nonatomic, retain) NSDate * lastUpdated;
#property (nonatomic, retain) NSString * notes;
#property (nonatomic, retain) NSString * owner;
#property (nonatomic, retain) NSString * productionID;
#property (nonatomic, retain) NSString * productionName;
#property (nonatomic, retain) NSNumber * scenesLocked;
#property (nonatomic, retain) NSNumber * shotNumberingStyle;
#property (nonatomic, retain) NSNumber * sortIndex;
#property (nonatomic, retain) NSNumber * status;
#property (nonatomic, retain) NSString * tagline;
#end
I then subclass this with a class called ZSProduction:
#import <Foundation/Foundation.h>
#import "ZSProductionCD.h"
#interface ZSProduction : ZSProductionCD
#end
The reason for subclassing is that I am likely to add a bunch of methods & possibly other properties. This way, if I make changes to the entity, I can write out a new ZSProductionCD class without affecting what I've done with ZSProduction.
Now here's the problem. I'm using ZSProduction in a view controller. But I'm having a problem with just one of the properties.
In this view controller, I declare a property:
#import "ZSProduction.h"
#interface [...]
#property (strong, nonatomic) ZSProduction *item;
#end
And then later, in a method:
self.productionNameField.text = self.item.productionName;
self.shotNumStyleControl.selectedSegmentIndex = [self.item.shotNumberingStyle intValue];
And that's where it goes wrong. XCode complains:
Property 'shotNumberingStyle' not found on object of type 'ZSProduction *'
Note that it doesn't complain about the productionName property, which works fine.
In the same view controller, if I use:
self.item.shotNumberingStyle = 0;
Then I get the same error. But if I use:
[self.item setValue:0 forKey:#"shotNumberingStyle"];
Then it works fine. Yet I can use:
self.item.highlightColour = [UIColor whiteColor];
with no problem at all. What gives?
Any clues would be appreciated.
Well, I sorted the problem, but I thought I'd leave this here in case someone else has something similar.
I realised that the three properties that were being inherited okay, and were accessible, wee ones I'd created in an earlier version of the ZSProduction class - one that didn't use Core Data (I'm currently refactoring to move from archives to CD).
It turned out that there were old ZSProduction.h and ZSProduction.m files on the disk, in the project subdir - but not in XCode. Seems that XCode was looking at these. The old files were in the root dir for the project, while the newer files were in a subdir (called 'Model'). I deleted the old files, restarted XCode & all is now tickety-boo.
I would like to ask you some opinion about what I'm doing. I know it works, but I'm not sure is proper to do what I'm doing.
I have a superclass Building that need to expose two NSString, name and description. No one should be able to modify those variables apart their subclasses.
To get this result I have created two public method on the base class:
#interface Building : NSObject
- (NSString *)name;
- (NSString *)description;
#end
Then on each subclass I'm creating a private interface with name and description properties and let the magic happen.
#interface Barrack()
#property (nonatomic, strong) NSString *name;
#property (nonatomic, strong) NSString *description;
#end
#implementation Barrack
#synthesize name, description;
...
#end
What you guys think about this?Is this a proper way to get this kind of result, anyone have better ideas about this topic?
Thanks for your opinion.
Best,
Enrico
Declare readonly properties in the interface, readwrite in the implementation class extension. No need for #synthesize. This is one of the main reason class extensions were added to Objective-C.
in Building.h
#interface Building : NSObject
#property (nonatomic, strong, readonly) NSString *name;
#property (nonatomic, strong, readonly) NSString *description;
#end
In Barrack.m
#interface Barrack ()
#property (nonatomic, strong, readwrite) NSString *name;
#property (nonatomic, strong, readwrite) NSString *description;
#end
#implementation Barrack
...
#end