I have the following UIViewController class:
FILE: ResultsDataViewController.h
#interface ResultsDataViewController : UIViewController
#property (nonatomic, strong) NSString* name;
#end
FILE : ResultsDataViewController.m
#import "ResultsDataViewController.h"
#interface ResultsDataViewController ()
#end
#implementation ResultsDataViewController
#synthesize data;
Then I have my UIView with class name Plot.h/m
Plot.h:
#interface PlotGraph : UIView <CPTBarPlotDataSource, CPTBarPlotDelegate>
#property (nonatomic, strong) NSString* receivedName;
#end
Plot.m:
#import "Plot.h"
#interface Plot()
#end
#implementation PlotGraph
#synthesize receivedName;
...
=====
Question:
HOW do I pass the value of name from my UIViewController and assign it to the variable receivedName in my UIView?
The UIView Plot is a view in my UIViewController DataViewController
(Note: #synthesize data; in your question is probably a typo. I'll assume you meant #synthesize name;. Also, #interface Plot() should probably be #interface PlotGraph().)
First, you need to have a reference to a PlotGraph object either as something you create in code or something that you load into an IBOutlet variable from your xib file or storyboard. Once you have that, either where you create it or in viewDidLoad:, it's simply something like:
plotView.receivedName = self.name;
Related
So I have been searching in a few hours for why my iPhone app hates me. This is the error I get:
Warning: local declaration of 'speedView' hides instance variable.
Here is my .m file
#implementation MainViewController
#synthesize speedCount;
#synthesize speedView;
#synthesize popoverController;
- (void)setspeedView:(UILabel *)speedView
{
[speedView setText: [NSString stringWithFormat:#"%d",speedCount]];
speedCount = 0;
speedCount++;
}
.h file
#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>
#interface MainViewController : UIViewController <LoginDelegate,WEPopoverParentView,PopoverControllerDelegate,MainMenuDelegate,MKMapViewDelegate,UIActionSheetDelegate,UIAccelerometerDelegate, CLLocationManagerDelegate>
{
AppDelegate *appDelegate;
IBOutlet MKMapView *userMap;
IBOutlet UILabel *speedView;
CLLocationManager *locationManager;
}
#property (strong, nonatomic) IBOutlet UILabel *speedView;
#property(nonatomic) int speedCount;
I really don't understand why it says that I am hiding the instance variable.
You have a ivar (an instance variable) called speedView.
In your method
- (void)setspeedView:(UILabel *)speedView
speedView is a local variable whose name clashes with the ivar.
If you are using a modern version of the compiler just remove the #synthesize directive.
It will be automatically added by the compiler in this form
#synthesize speedView = _speedView
which will create the ivar _speedView, whose name doesn't clash anymore with the local variable.
Also note that declaring both the instance variable and the property is redundant. The ivar will be automatically created by the (implicit) #synthesize directive.
Here's a "modern" version of your class:
.h
#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>
#interface MainViewController : UIViewController <LoginDelegate,WEPopoverParentView,PopoverControllerDelegate,MainMenuDelegate,MKMapViewDelegate,UIActionSheetDelegate,UIAccelerometerDelegate, CLLocationManagerDelegate>
#property (strong, nonatomic) IBOutlet UILabel *speedView;
#property (strong, nonatomic) CLLocationManager *locationManager;
#property (strong, nonatomic) IBOutlet MKMapView *userMap;
#property (strong, nonatomic) AppDelegate *appDelegate;
#property (nonatomic) int speedCount;
.m
#implementation MainViewController
- (void)setspeedView:(UILabel *)speedView {
[speedView setText:[NSString stringWithFormat:#"%d", self.speedCount]];
self.speedCount = 0;
self.speedCount++;
}
Please note:
properties are nice: use them whenever you can
#synthesize is implicit
the implicit version of #sythesize declares a _ivar for the property ivar
always access variables through the getters/setters, i.e. self.ivar, a part from init methods. If you need to access the var directly use _ivar or self->_ivar
As a final remark, this looks a bit weird
self.speedCount = 0;
self.speedCount++;
and it could be replaced with
self.speedCount = 1;
Are you sure it's what you mean? Also, as noted in the comments by others, you are not using the method parameter speedView. That smells bad and you may want to double check your implementation.
I have read question after question about people getting the same error as me, but I simply do not understand them, so before you go searching for duplicate questions, maybe someone can explain to me what I am doing wrong with this subclassing deal.
I have a subclass of UIImageView called swapView that I want to subclass to override the method -(void)count for special cases. I went to subclass this as I have any pre-existing UIKit class, but when I tried to build and run the project, I get this error:
Attempting to use the forward class 'swapView' as superclass of 'coinView'
I have tried putting both the #import statement of swapView and #class swapView in coinView.h and I've tried putting the import statement in coinView.m, but it refuses to build because of this continued error. If I move the import statement into the .m file, all references to the superclass's methods and properties, such as #property (nonatomic) int max; cause errors as well.
What am I doing wrong?
swapView.h
#import <UIKit/UIKit.h>
#import "ViewController.h"
#class ViewController;
#interface swapView : UIImageView
{
NSTimer* tmr;
}
#property (nonatomic) int current;
#property (nonatomic) int max;
#property (nonatomic, retain) UIImage* firstImage;
#property (nonatomic, retain) UIImage* secondImage;
#property (nonatomic) BOOL smallMax;
#property (nonatomic, retain) ViewController* pvc;
- (BOOL)testCollision:(CGPoint)point;
- (float)randomFloatBetween:(float)smallNumber bigNumber:(float)bigNumber;
#end
coinView.h
#import "swapView.h"
#class swapView;
#interface coinView : swapView
- (void)count;
- (void)move;
#end
For inheritance, the superclass MUST be inherited.
coinView.h
#import "swapView.h"
#interface coinView : swapView
- (void)count;
- (void)move;
#end
You're both forward declaring and importing ViewController.h in your swapView, which may cause compiler to complain.
swapView.h
#import <UIKit/UIKit.h>
#class ViewController
#interface swapView : UIImageView
.
.
.
#end
I have a ViewController, and a UIView.
The UIView has a delegate, and the delegate function is set in the ViewController.
All I want to do, is have the delegate function defined in a separate file. So the UIView.m #imports the separate file, instead of all the ViewControllers which use the UIView.
I believe this is a standard procedure, but keep falling over myself trying to get it to work. :| Would really appreciate some help. Thanks.
myViewController.h
#import <UIKit/UIKit.h>
#import "myUIView.h"
#protocol ModalViewDelegate
-(void)didReceiveMessage:(NSString *)message;
#end
#interface myViewController : UIViewController <ModalViewDelegate>
#property (nonatomic, strong) myUIView *myUIViewItem;
#end
myViewController.m
#import "myViewController.h"
#import "myUIView.h"
#interface myViewController ()
#end
#implementation myViewController
#synthesize myUIViewItem;
- (void)didReceiveMessage:(NSString *)message { //<<< THIS IS WHAT
NSLog(#"Message from button: %#", message); //<<< NEEDS MOVING
}
- (void)viewDidLoad
{
…
myUIViewItem.delegate = self;
…
myUIView.h
#import <UIKit/UIKit.h>
#protocol ModalViewDelegate;
#interface myUIView : UIView {
id<ModalViewDelegate> delegate;
}
#property (nonatomic, strong) id<ModalViewDelegate> delegate;
myUIView.m
#import "myUIView.h"
#import "myViewController.h"
#implementation myUIView
#synthesize delegate;
...
[delegate didReceiveMessage:#"Data from UIView!"];
well, there is one method actually,
Just take one .h file and lets say connectionDelegate.h and declare your protocol init
In connectionDelegate.h:
#import <UIKit/UIKit.h>
#protocol ConnectionDelegate
-(void)getResult:(NSString*)_result;
#end
Then in your view controller:
#import "ConnectionDelegate.h"
#interface myViewController : UIViewController <ConnectionDelegate>
{
id delegate;
}
then in .m file, by just call the method
[delegate getResult:_result];
Edit regarding the warnings:
You need to declare the method in view controller, you need to do like this.
[self getResult:urlDataString];
-(void)getResult:(NSString*)_result{
[delegate getResult:_result];
}
Based on your comment:
I want to have the function 'didReceiveMessage' defined in a SEPARATE
file. So that I don't have to repeat it in every ViewController that
uses the UIView and delegate. e.g. ModalViewDelegate_Action.h and
ModalViewDelegate_Action.m
The way I was given was to use a subclass, and that's been working great for me. In my iOS projects I have a class called BaseViewController, which is a subclass of UIViewController. I put lots of code in it related to HUD management, NSOperations management, etc. Then virtually all my view controllers are subclasses of it.
I have a superclass of UIViewController - MasterViewController which declares a property called itemsViewController. This declares a method called from the MasterViewController, and is wired up via a storyboard in IB.
I have a subclass of MasterViewController which redeclares this property as a specific iPad version, but I can't access the redeclared property from the parent class.
MasterViewController
#interface MasterViewController : UIViewController {
}
#property (nonatomic, strong) IBOutlet ItemsViewController *itemsViewController;
#end
#implementation MasterViewController
#synthesize itemsViewController;
-(void)viewDidLoad {
// I can access itemsViewController in viewDidLoad.
}
#end
MasterViewController_iPad
#interface MasterViewController_iPad : MasterViewController {
IBOutlet ItemsViewController_iPad *_itemsViewController;
}
#property (nonatomic, strong) IBOutlet ItemsViewController_iPad *itemsViewController;
#end
#implementation MasterViewController_iPad
#synthesize itemsViewController = _itemsViewController;
-(void)viewDidLoad {
[super viewDidLoad];
// when I call super viewDidLoad, itemsViewController is nil, as though the property hasn't been overriden
// _itemsViewController is not nil in viewDidLoad.
}
#end
Am I misunderstanding the way property inheritance works in Objective-C?
You can't change the type signature of a method when you override a superclass method.
MasterViewController has these methods:
(void)setItemsViewController:(ItemsViewController *)foo
(ItemsViewController *)itemsViewController
But you're trying to give MasterViewController_iPad these methods:
(void)setItemsViewController:(ItemsViewController_iPad *)foo
(ItemsViewController_iPad *)itemsViewController
Which you can't do: you can't overload the same method name but have different types for the arguments.
If ItemsViewController_iPad is a subclass of ItemsViewController, a quick solution would be to keep the same signature as in MasterViewController but simply use an ItemsViewController_iPad when you set the property.
You can use category if you'd like to override property. Here is example:
I have PDFFileChooserViewController with PDFFileModel and PDFFilesDataSource and some logic related to this properties.
#class PDFFileModel, PDFFilesDataSource;
#interface PDFFileChooserViewController : UIViewController
#property (nonatomic, strong) PDFFileModel* selectedModel;
#property (nonatomic, strong) PDFFilesDataSource*dataSource;
#end
Then I'd like to add specific ViewController for choosing files from Dropbox but my model have some additional fields for example dropboxPath and my DropboxDataSource gets files using another way. So I decided to create category and override this properties:
#import "PDFFileChooserViewController.h"
#class DropboxFileModel,DropboxDataSource;
#interface DropboxViewController : PDFFileChooserViewController
#end
#interface DropboxViewController (ModelCategory)
#property(nonatomic, strong) DropboxFileModel* selectedModel;
#property(nonatomic, strong) DropboxDataSource* dataSource;
#end
Notice that this category will be visible inside DropboxViewController only where I can manipulate with that properties but another classes see only super class interface
In my AppDelegate.h file i written the following code
#interface iBountyHunterAppDelegate : NSObject <UIApplicationDelegate> {
UITabBarController *tabcontroller;
}
#property (nonatomic,retain) IBOutlet UITabBarController *tabcontroller;
and in AppDelegate.h file I synthesize it.
#synthesize tabcontroller;
but in #synthesize line i get an error and the msg is: "MISSING CONTEXT FOR PROPERTY IMPLEMENTATION DECLARATION"
can anyone tell me how to solve it?
I suspect you have put the #synthesize outside of your #implementation. It should look something like this
// iBountyHunterAppDelegate.m
#import "iBountyHunterAppDelegate.h"
#implementation iBountyHunterAppDelegate
#synthesize tabcontroller; // note that this is between #implementation and #end
// other stuff
#end
"and in AppDelegate.h file I synthesize it." Probably it´s just misspelled but it has to be in .m file :P
#interface iBountyHunterAppDelegate : NSObject <UIApplicationDelegate>
{
UITabBarController IBOutlet *tabcontroller;
}
#property (nonatomic,retain) IBOutlet UITabBarController *tabcontroller;
and in AppDelegate.h file I synthesize it.
#synthesize tabcontroller;
synthesize your property in controller(iBountyHunterAppDelegate.m) file instead of interface(.h) file