EDIT:
In my ViewController i am adding multiple buttons to its view.
ViewController1.h
#import <UIKit/UIKit.h>
#interface ViewController1 : UIViewController
-(void)buttonTapped:(id)sender;
#end
ViewController1.m
#import "MyViewCreatorClass.h"
#interface ViewController1 ()
#end
#implementation ViewController1
- (void)viewDidLoad {
[self.view addSubView:[MyViewCreatorClass createButtonWithParentView:self]];
}
-(void)buttonTapped:(id)sender{
NSLog(#"tapped");
}
The implementation for creating the button is inside the class 'MyViewCreatorClass'
MyViewCreatorClass.h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import "MainViewController.h"
#interface MyViewCreatorClass : NSObject
+ (UIButton*)createButtonWithParentView:(ViewController1*)parentView;
#end
MyViewCreatorClass.m
#import "MyViewCreatorClass.h"
#implementation MyViewCreatorClass
+ (UIButton*)createButtonWithParentView:(ViewController1*)parentView {
UIButton *button = [[UIButton alloc] initWithFrame:....];
//some other implementation (title, color etc.)
[button addTarget:parentView action:(buttonTapped:) forControlEvents:UIControlEventTouchUpInside];
return button;
}
#end
At first i had this implementation inside ViewController1 and it worked fine, but now
the warning "undeclared selector 'buttonTapped:'" shows up (this was solved by declaring the method buttonTapped: in ViewController1.h)
the method won't get called as i moved this method into MyViewCreatorClass.
I know that parentView needs to be an instantiated object, and it is. In another method of MyViewCreatorClass i'm also setting some views delegate to parentView and it works.
I even tried to use this method as an instance method not a class method but it did not work either.
What could it be that prevents the method from being called?
Additional question:
One could also use protocols to achieve this (comments). I know how to use protocols, but sadly i don't know how to implement this so a button calls a method on touchUpInside.
Any ideas?
Related
I have UIViewController named ParentViewController.h and .m
Then I added UIView inside this ParentViewController.
I had uiview.h and uiview.h added and assigned to UIView inside ParentViewController.
From
-(void)drawRect:(CGRect)rect {}
which is located in uiview.m, I need to access to properties inside ParentViewController.
How do I do this? Am I using UIView wrong?
ParentViewController.h
#import <UIKit/UIKit.h>
#interface ParentViewController : UIViewController
//I want my uiview to access this variable.
#property (nonatomic, strong) NSMutableArray *usedByUIView;
#end
ParentViewController.m
#import "ParentViewController.h"
#import "uiview.h"
#implementation ParentViewController
- (void)viewDidLoad {
...
}
#end
uiview.h
#import <UIKit/UIKit.h>
#interface uiview : UIView
#end
uiview.m
#import "uiview.h"
#implementation uiview
-(id) initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if(self){
}
return self;
}
- (void)drawRect:(CGRect)rect {
NSLog(#"start drawing using the data from usedByUIView");
}
#end
There are a few answers on this subject but, summarizing them, you don't, at least not the way that you're doing it. UIView's do not have access to their view controller's and aren't supposed to need access. Of course, in the real world, sometimes it's not worth the overhead of coding around independent views so people hack in access to the controller access. This can be done by keeping an instance variable in the view, pointing to the controller, and assigning a reference to it after the view has loaded, or by overriding the init so you also pass a view controller, or lots of other ways. But before you do that think through the logic of why you want access to the controller from the view and see if there isn't a different way to do it.
I am working on an iOS project and wanted to include a UIView that is reused on multiple screens in the application (appearing at the bottom of different UIViews). I am using a storyboard for the UI work so far but created an .xib file to be used by the reusable view (playerView in code below).
The view gets added but the button I have added to the View is unresponsive, also my background color cannot be changed on the view. I have tried to set background color programmatically and in the .xib with no luck. Very weird symptoms and I tried to instantiate the view from #5 of this article and probably did something wrong. I dont fully understand everything in the article which makes me nervous - for instance my showSubclassedView method returns IBAction but I just call the function name in code and dont use a button (I did hook up the buttons in the view as the article described though).
Here is the code:
EventViewController.m (where I trry and add PlayerView)
#import "EventViewController.h"
#import "PlayerView.h"
#interface EventViewController ()
-(IBAction)showSubclassedView;
#end
#implementation EventViewController
-(IBAction)showSubclassedView
{
[PlayerView presentInViewController:self];
}
PlayerView.h (.h for reusable view)
#import <UIKit/UIKit.h>
#import "Utils.h"
#class PlayerView;
#protocol PlayerViewDelegate
-(void)playerViewTouchedUp:(PlayerView*) playerView;
-(void)playerViewDidDismiss:(PlayerView*) playerView;
#end
#interface PlayerView : UIView
+(void)presentInViewController:(UIViewController<PlayerViewDelegate>*) playerView;
-(IBAction)viewTouchedUp;
-(IBAction)dismiss;
#end
PlayerView.m (.m for reusable view)
#import "PlayerView.h"
#interface PlayerViewOwner : NSObject
#property(nonatomic,weak) IBOutlet PlayerView *playerView;
#end
#implementation PlayerViewOwner
#end
#interface PlayerView ()
#property (nonatomic, weak) UIViewController <PlayerViewDelegate> *delegateViewController;
#end
#implementation PlayerView
+(void)presentInViewController:(UIViewController<PlayerViewDelegate> *)viewController
{
PlayerViewOwner *owner = [PlayerViewOwner new];
[[NSBundle mainBundle] loadNibNamed:NSStringFromClass(self) owner:owner options:nil];
owner.playerView.delegateViewController = viewController;
[viewController.view addSubview:owner.playerView];
}
-(IBAction)viewTouchedUp
{
//forward to delegate
NSLog(#"you clicked a button");
[self.delegateViewController playerViewTouchedUp:self];
}
-(IBAction)dismiss
{
[self removeFromSuperview];
// Forward to delegate
[self.delegateViewController playerViewDidDismiss:self];
}
#end
PlayerView.xib has a UIbutton on it that connects it to viewTouchedUp method in PLayerView.m
Is there anything I did wrong in the code above? Is this the best way to do a reusable view to display on other views?
Thank you!
Here's a workaround I found after not being able to solve this.
New implementation is from this article
I reverted my changes from my initial question and implemented this. It lacks the nice protocol separation for talking back and forth and I might need something like this later but I think now I can still implement a protocol to solve this.
At least with this solution I have usable items in my view and a background that changes!
i have two view controllers, AbcViewController and XyzViewController. Both controllers behave similarly. Each has a "add" button which opens up a AddNewAbcViewController and AddNewXyzViewController respectively.
On AddNewAbcViewController, when the button "submit" is taped, it does it necessary stuff and close, bringing it back to AbcViewController. I am using delegate here where AbcViewController does the closing of AddNewAbcViewController. This works.
Now I want to do the same for XyzViewController and AddNewXyzViewController, but it is not working. When the btnSubmit is called in AddNewXyzViewController, it didn't enter into XyzViewController dimiss method. I have scanned through my codes many times but don't find anything extra not added. I even gave a different dismiss method name in XyzViewController and AddNewXyzViewController but that didn't work either. What did I miss?
here are my snippets for AbcViewController and AddAbcViewController. The codes for Xyz are identical:
class AddNewAbcViewController.h is
#import <Foundation/Foundation.h>
// protocol
#protocol AddNewAbcProtocol <NSObject>
-(void)dismiss;
#end
#interface AddNewAbcViewController : UIViewController<UITextViewDelegate>
#property(nonatomic, weak)id<AddNewAbcProtocol> delegate;
#end
class AddNewAbcViewController.m is
#interface AddNewAbcViewController() <UINavigationControllerDelegate, UIImagePickerControllerDelegate>
...
#end
#implementation AddNewAbcViewController
...
- (IBAction)btnSubmit:(id)sender
{
[self.delegate dismiss];
}
#end
class AbcViewController.h is
#import <Foundation/Foundation.h>
#import "AddNewAbcViewController.h"
#interface AbcViewController : UIViewController<AddNewAbcProtocol, UISplitViewControllerDelegate>
...
#end
class AbcViewController.m is
#implementation AbcViewController
-(void)dismiss
{
NSLog(#"delegated to dismiss()");
[self dismissViewControllerAnimated:YES completion:nil];
}
#end
As everyone explained, basically you forgot a line of code like ".delegate = self".
Here's a handy beginner's intro to delegates.
https://stackoverflow.com/a/4213005/294884
Use if statement to see if delegate works:
if ([self.delegate respondsToSelector:#selector(dismiss)])
{
[self.delegate dismiss];
}
Create AddNewXyzViewController as an instance variable, but not a local variable.
I have made a simple app to test this and cannot figure it out. I have an iPad storyboard where I have put two container views as shown below. I have a label in one view and a button in another. My button will increment the label, 1 number at a time.
My problem is not passing the value or incrementing, but getting the view to load the new value.
Each container has its own ViewController
Some code below, although very sparse as Ive written a bunch and deleted as it didn't work. Please help with the correct format. I would like to keep this general format, updating global variable within button and it updating the label.
LabelViewController.h
#import <UIKit/UIKit.h>
#interface LabelViewController : UIViewController
#property (weak, nonatomic) IBOutlet UILabel *checkLabel;
-(void)loadLabel;
#end
LabelViewController.m
#import "LabelViewController.h"
#import "ParentViewController.h"
#interface LabelViewController ()
#end
#implementation LabelViewController
#synthesize checkLabel;
-(void)loadLabel{
checkLabel.text = [NSString stringWithFormat:#"%d",value];
[self.view setNeedsDisplay];
}
- (void)viewDidLoad
{
[self loadLabel];
[super viewDidLoad];
}
ButtonViewController.h
#import <UIKit/UIKit.h>
#interface ButtonViewController : UIViewController
- (IBAction)checkButton:(id)sender;
#end
ButtonViewController.m
#import "ButtonViewController.h"
#import "ParentViewController.h"
#import "LabelViewController.h"
#interface ButtonViewController ()
#end
#implementation ButtonViewController
- (IBAction)checkButton:(id)sender {
value++;
NSLog(#"%d",value);
LabelViewController *fnc = [[LabelViewController alloc] init];
[fnc loadLabel];
}
- (void)viewDidLoad
{
[super viewDidLoad];
}
Picture at:
http://farm4.staticflickr.com/3822/9469907420_746db25b23_b.jpg
In ButtonViewController, you don't want to be alloc init'ing an instance of LabelViewController -- the one that's on screen already exists. Both child view controllers are instantiated just before the parent controller is. So, what you need to do is get a reference to the LabelViewController that's on screen. You can do that with self.parentViewController.childViewControllers[0] (that 0 might have to be 1 -- I don't know which controller is which).
LabelViewController *fnc = self.parentViewController.childViewControllers[0];
[fnc loadLabel];
I ultimately want to write an iOS app incorporating ALAssetsLibrary, but as a first step toward understanding delegation, I'm trying to pass a simple message between two view controllers. For some reason, I can't seem to get the message to pass. In particular, the delegate object (derpy) doesn't appear to exist (if(self.derpy) returns NO)).
I asked the same question on the Apple forums and was told that I should be using segues and setting properties / calling methods using self.child instead, but that seems strange. If I were to pass messages using the parent / child properties, would I still be able to create my views in Interface Builder? Once I have my two views set up, say inside a UINavigationController, I'm not sure how to actually "wire them up" so I can pass messages between them. Sorry if the question is overly broad.
Here's the controller I'm declaring the protocol in (called PickerViewController):
Interface:
#import <UIKit/UIKit.h>
#import <AssetsLibrary/AssetsLibrary.h>
#protocol DerpDelegate <NSObject>
#required
- (void) test;
#end
#interface PickerViewController : UIViewController
#property (nonatomic, assign) id<DerpDelegate> derpy;
#end
Implementation:
#import "PickerViewController.h"
#interface PickerViewController ()
#end
#implementation PickerViewController
- (void)viewDidLoad
{
[super viewDidLoad];
if (self.derpy) { // If the delegate object exists
[self.derpy test]; // send it this message
} else {
NSLog(#"Still not working."); // This always returns (i.e., self.derpy doesn't exist)
}
}
Delegate controller (MainViewController) interface:
#import <UIKit/UIKit.h>
#import "PickerViewController.h"
#interface MainViewController : UIViewController <DerpDelegate> // public promise to implement delegate methods
#property (strong, nonatomic) PickerViewController *picker;
- (void) test;
#end
And lastly, the delegate controller (MainViewController) implementation:
#import "MainViewController.h"
#import "PickerViewController.h"
#interface MainViewController ()
#end
#implementation MainViewController
// Here's that method I promised I'd implement
- (void) test{
NSLog(#"Test worked."); // This never gets called
}
- (void)viewDidLoad {
[super viewDidLoad];
self.picker.derpy = self;
//lazy instantiation
- (PickerViewController *) picker{
if(!_picker) _picker = [[PickerViewController alloc]init];
return _picker;
}
EDIT: Many thanks to rydgaze for pointing me in the right direction with self.picker.derpy = self, but for some reason, things still aren't working properly. Importantly, once that property has been set, if(self.picker.derpy) returns YES from MainViewController. But if(self.derpy) is still returning NO when called from inside the PickerViewController's viewDidLoad. How can the property exist and not exist at the same time?
You need to be sure that you're setting the delegate on the instance of the view controller that you put on screen. If you're using a navigation controller and segues to go between MainViewController and PickerViewController, then you should set the delegate in prepareForSegue:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
self.picker = (PickerViewController *)segue.destinationViewController;
self.picker.derpy = self;
}
You need to populate the delegate first.
Basically, your MainViewController shoudl at somepoint do a
picker.derpy = self;
Then when the delegate fires in PickerViewController, the callback will happen.
Edit:
A good practice is to do something like in PickerViewController
#property (nonatomic, assign) id<DerpDelegate > derpy;
and in your MainViewController indicate that you will implement the delegate
#interface MainViewController : UIViewController<DerpDelegate>
Eventually in your implementation of MainViewController
You will have something like
picker = [[PickerViewController alloc]init];
picker.derpy = self;
[picker doYourThing];
Once picker is all done, it may want to return results using the delegate.