I have a custom UITableViewCell:
#interface EditingTableViewCell : UITableViewCell <UITextFieldDelegate> {
UITextField *editableText;
UILabel *textLabel;
}
And I did receive editingDidEnd message from UITextField editableText. Now how can I pass it's message to UITableViewController which creates this cell?
Is creating ivar like this id delegate; within cell and set it to the tableViewController instance an only way?
I think i found a way to do a good job...
Create #protocol for this cell
// EditingCellDelegate.h
#protocol EditingCellDelegate
#optional
- (void)textLabelEditDidEnd:(UITextField *)textField;
#end
Add ivar into EditingTableViewCell class
// EditingTableViewCell.h
...
#property (nonatomic, assign) id <EditingCellDelegate> delegate;
So this way i can pass message to the UITableViewController that conforms that cell's protocol. Of course you have to check that class conformsToProtocol and respondsToSelector. Now I can call it. Something like this:
//EditingTableViewCell.m
- (IBAction)editDone:(id)sender {
if([[self delegate] respondsToSelector:#selector(textLabelEditDidEnd:)]) {
[[self delegate] textLabelEditDidEnd:(UITextField *)sender];
}
}
Related
In my app I'm trying to pass data from the parent view to the child view. However, when I run the app the delegate method isn't being called.
Here is the code on how I implemented the custom delegate:
parent.h
#protocol SLBWallViewControllerDelegate <NSObject>
- (void) pictureToBeUploaded:(id)picture;
#end
#interface SLBWallViewController : UIViewController <UIActionSheetDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate>
- (IBAction)createPotButtonPressed:(id)sender;
#property (weak, nonatomic) id <SLBWallViewControllerDelegate> delegate;
#end
parent.m
[self.delegate pictureToBeUploaded:info[UIImagePickerControllerEditedImage]];//i'm taking the pic from a uiimagepicker
child.h
#interface SLBPostViewController : UIViewController <SLBWallViewControllerDelegate>
#property (weak, nonatomic) IBOutlet UIImageView *picture;
#end
child.m
#pragma mark - Wall View Controller Delegate
- (void)pictureToBeUploaded:(id)picture{
self.picture.image = picture;
}
Is there anything wrong or missing?
Well, the problem probably (edit: confirmed in the comments) is that self.delegate is nil at that point. So you send a message to nil and nothing happens of course. What you have to do is make sure that you assign a Child instance to delegate property before trying to send the message. Something like this for example:
//...
self.delegate = //.. a 'Child' instance
//...
[self.delegate pictureToBeUploaded:info[UIImagePickerControllerEditedImage]];
//(1) In Child in .h file create one property
#property (nonatomic,strong) UIImage * someImage;
//(2) In Child in .m file override the property
-(void)setSomeImage:(UIImage *)someImage{
_someImage=someImage;
self.picture.image = self.someImage;
}
//(3) In Parent in .m file set image to child's 'someImage' property
childsObject.someImage= UIImagePickerControllerEditedImage;
I have a screen with a button. Clicking the button will display a popover with two buttons. I want to be able to use the following method when the popover is dismissed:
#pragma mark - UIPopoverControllerDelegate
- (void)popoverControllerDidDismissPopover:(UIPopoverController *)popoverController {
NSLog(#"OrderViewController.m -popoverControllerDidDismissPopover start");
}
The popover view has its own class:
#import <UIKit/UIKit.h>
#import "MenuItemModel.h"
#interface SelectedItemsOptionsViewController : UIViewController
#property (weak) id <UIPopoverControllerDelegate> delegate;
#property (strong, nonatomic) MenuItemModel *item;
#end
The class which creates the popover has:
#interface OrderViewController : UIViewController <PageViewControllerDelegate,
UITableViewDataSource, UITableViewDelegate, ServiceConnectorDelegate,
UIPopoverControllerDelegate>
So the OrderViewController - wants to know when SelectedItemsOptionsViewController has been dismissed.
I have the method declared (first block of code) and I am setting the delegate as:
SelectedItemsOptionsViewController *destViewController = (SelectedItemsOptionsViewController *)segue.destinationViewController;
popSegue = (UIStoryboardPopoverSegue *)segue;
[destViewController setDelegate:self];
destViewController.item = toDisplay;
So I am setting the delegate OK as far as i'm aware... the delegate property is #syntheized in th SelectedItemsOptionsViewController.m and well, its driving me a bit crazy.
I could be misunderstanding something here but looks like you're assigning the delegate for a UIViewController class, but where are you assigning the popOver its delegate, in the storyboard?
I have a Subclass of NSObject in which I want to call IMMEDIATELY (a sort of -(void)viewDidLoad) a method (in this case to load a MkMapView): what's the better way to do this? I think I cant use viewDidLoad, so can I use performSelector?
SubClass.h
#interface Mysubclass : NSObject <MKMapViewDelegate> {
}
SubClass.m (1st alternative)
-(id)init{
self = [super init];
if ( self != nil ) {
// THE CODE TO INITIALIZE MKMAPVIEW
}
return self
}
OR
SubClass.m (2nd alternative)
-(id)init{
[self performSelector:#selector(myMethod)];
return self;
}
-myMethod{
// THE CODE TO INITIALIZE MKMAPVIEW
}
What's the better (or correct) alternative? Its possible to avoid -(id)init? Or everytime I add a subclass, to call a method I have to write it into -(id)init? Thank you!
There is no reason to use -performSelector: in this context. If you want to add a method that initializes the MKMapView when your object is created, call the method from within the if (self) block:
- (id)init
{
self = [super init];
if (self) {
[self setupMapView];
}
return self;
}
- (void)setupMapView
{
// THE CODE TO INITIALIZE MKMAPVIEW
}
It is a matter of personal preference/style whether to have a second method -setupMapView or to simply leave the code for setting up the MKMapView in the if (self) block of the -init method or to break the code off into a second method -setupMapView called from -init.
That being said, it sounds like other things may be off with your setup. Your MKMapView should [most likely] be within a UIViewController subclass (which will probably have an associated XIB), so you will be have access to -viewDidLoad. Note that your UIViewController subclass will serve as the delegate to your MKMapView.
Update 1
In your UIViewController subclass instance (I'll assume you called it ViewController, you should have an IBOutlet to an MKMapView object. Do this in ViewController.h either by (1) adding an instance variable
#interface ViewController : UIViewController
{
IBOutlet MKMapView *myMap;
}
#end
or by (2) adding a property
#interface ViewController : UIViewController
#property (nonatomic, strong, readwrite) IBOutlet MKMapView *myMap;
#end
Now open ViewController.xib in Interface Builder. You should have an MKMapView inside the view. If you don't already, add one from the Object Library. Right click on File's Owner. Locate the row with the item myMap. Drag from the circle on the right end of the row to the MKMapView in the visible view.
Your ViewController class now has an outlet to the MKMapView. You will be able to send messages to the MKMapView subview of your view controllers view after it has been loaded.
You should have a property or an instance variable for your SubClass instance so that it doesn't get destroyed as soon as -viewDidLoad returns. Do this again by either adding an instance variable to ViewController.h
#interface ViewController : UIViewController
{
IBOutlet MKMapView *myMap;
SubClass *istance;
}
#end
or by adding a property
#interface ViewController : UIViewController
#property (nonatomic, strong, readwrite) IBOutlet MKMapView *myMap;
#property (nonatomic, strong, readwrite) SubClass *istance;
#end
Now, in ViewController.m, you need to define -viewDidLoad so that self.istance is set as the delegate of self.myMap. In the comments, I had suggested creating your own initializer -initWithMapView:. If you plan on having SubClass do some extensive set-up of your MKMapView, that makes sense. If you just want SubClass to be the delegate of the MKMapView, there's no need for such a method.
Let's consider both cases:
(1) using a method -[SubClass initWithMapView:]:
In ViewController.m you'll have (within the #implementation of ViewController)
- (void)viewDidLoad
{
self.istance = [[SubClass alloc] initWithMapView:self.myMap];
}
In SubClass.h you'll have (within the #interface of SubClass)
- (id)initWithMapView:(MKMapView *)mapView;
#property (nonatomic, weak, readwrite) MKMapView *mapView;
In SubClass.m you'll have (within the #implementation of SubClass)
- (id)initWithMapView:(MKMapView *)mapView
{
self = [super init];
if (self) {
self.mapView = mapView;
self.mapView.delegate = self;
//more setup of mapView.
}
return self;
}
(2) using -[SubClass init]:
Instead, in ViewController.m you'll have
- (void)viewDidLoad
{
self.istance = [[SubClass alloc] init];
self.myMap.delegate = self.istance;
}
The setup:
PickerView (spinSelector) and label (chosenItem) added to ViewController.
Created separate delegate class files (SpinDelegate m&h) for the PickerView delegate.
Created instance of the delegate (SpinDelegate *mySpinDelegate)
Assigned delegate property to delegate instance
ViewController.h
#interface ViewController : UIViewController
{
SpinDelegate *mySpinDelegate;
}
#property (nonatomic, weak) IBOutlet UILabel *chosenItem;
#property (nonatomic, strong) IBOutlet UIPickerView *spinSelector;
ViewController.m
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
mySpinDelegate=[[SpinDelegate alloc]init];
self.spinSelector.delegate=mySpinDelegate;
self.spinSelector.dataSource=mySpinDelegate;
}
SpinDelegate.h
#interface SpinDelegate : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate>
{
ChoiceData *choiceItems;
}
#end
SpinDelegate.m
#pragma mark - PickerView Delegate
- (NSString *)pickerView:(UIPickerView *)pickerView
titleForRow:(NSInteger)row
forComponent:(NSInteger)component{
return [choiceItems.choiceList objectAtIndex:row];
}
Next is to use the method:
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component;
This is part of the UIPickerViewDelegate protocol. Using this, to simply change the UILabel (chosenItem) in the ViewController to value of row. Something like "The picked item is %i",row
I've read and searched through a ton of posts and questions on UIViewController to UIViewController messaging and looked at protocol/delegate, singleton, NSNotificationCenter... it just seems to me that there is a syntax I am missing to address the parent/super? The ViewController created the instance of the delegate, doesn't the delegate have scope?
Please educate me on this. : )
You can do something like this:
ViewController.h
#import "SpinViewController.h"
#interface ViewController : UIViewController<SpinViewControllerDelegate>
{
}
#property (nonatomic, weak) IBOutlet UILabel *chosenItem;
#property (nonatomic, strong) IBOutlet UIPickerView *spinSelector;
ViewController.m
- (void)someFunction
{
mySpinViewController=[[SpinViewController alloc]init];
mySpinViewController.delegate=self;
// show or present mySpinViewController
}
//implement the followed protocol's method
-(void) optionSelected:(NSString*)cellValue{
}
SpinViewController.h
#protocol SpinViewControllerDelegate <NSObject>
#optional
-(void) optionSelected:(NSString*)cellValue;
#end
#interface SpinViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate>
{
ChoiceData *choiceItems;
}
#property (nonatomic,retain)id <SpinViewControllerDelegate> delegate;
#end
SpinViewController.m
-(void) pickerValueSelectedOrSimilarFn:(NSString*)cellValue{
// this is how you give a callback to classes following the protocol
[self.delegate optionSelected:cellValue];
}
I'm creating a 3 layer navigation popup controller and on the 3rd popup controller I have a delegate method to access dismissPopup method that is in the parent class. I can't seem to call it, my NSLog messages in the function in the parent class isn't even showing so I must be either using delegation wrong or I'm calling it incorrectly.
The 3 classes ParentViewController has a toolbar with a button that brings up the table view --> RegionViewController is the First table view controller with items --> ConusViewController is the 2nd table view controller that is pushed onto the navigation stack. I'm trying to call the method dismissPopover that is in the parent method with a delegation after the selection is clicked on so the whole popover goes away.
In the ConusViewController if the delegation had worked I would have seen "Method Accessed" from the function in the parent class. It doesn't show so I must be using delegation wrong.
Sorry for being so wordy on my post, I wanted to be complete on what I'm trying to do here. Thanks.
ParentViewController.h
#import <UIKit/UIKit.h>
#import "ConusViewController.h"
#interface EnscoWXViewController : UIViewController <ConusViewControllerDelegate> {
UIPopoverController *popoverController;
IBOutlet UIWebView *webImageDisplay;
ConusViewController *cViewController;
}
#property (nonatomic, retain) UIPopoverController *popoverController;
#property (nonatomic, retain) UIWebView *webImageDisplay;
#property (nonatomic, retain) ConusViewController *cViewController;
-(IBAction) buttonShowRegion:(id) sender;
#end
ParentViewController.m
#import "ParentViewController.h"
#import "RegionViewController.h"
#implementation ParentViewController
#synthesize cViewController;
-(IBAction) buttonShowRegion:(id) sender {
...
}
-(void)dismissPopover {
[popoverController dismissPopoverAnimated:YES];
printf("Method Accessed\n");
}
- (void)viewDidLoad {
cViewController = [[ConusViewController alloc] init];
cViewController.delegate = self;
[super viewDidLoad];
}
RegionViewController.m
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
switch (indexPath.row) {
case 0: {
ConusViewController *conusViewController = [[ConusViewController alloc] initWithNibName:#"ConusViewController" bundle:nil];
conusViewController.contentSizeForViewInPopover = CGSizeMake(320, 350);
[self.navigationController pushViewController:conusViewController animated:YES];
[conusViewController release];
break;
}
case 1: {
break;
}
}
}
ConusViewController.h
#import <UIKit/UIKit.h>
#protocol ConusViewControllerDelegate <NSObject>
#required
- (void)dismissPopover;
#end
#interface ConusViewController : UITableViewController {
NSMutableArray *conusItems;
id delegate;
}
#property (nonatomic, assign) id <ConusViewControllerDelegate> delegate ;
#end
ConusViewController.m
#import "ConusViewController.h"
#import "ParentWXViewController.h"
#implementation ConusViewController
#synthesize delegate;
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
NSString *itemRequested = [conusItems objectAtIndex:indexPath.row];
NSLog(#"logging: %#", itemRequested);
[delegate dismissPopover];
[itemRequested release];
}
Just before calling [delegate dismissPopover], check if delegate is actually set. It probably isn't.
I see in ParentViewController.m you create an instance of ConusViewController and set its delegate, but never display it. In RegionViewController.m you create another instance of ConusViewController without setting its delegate and that is the one that seems to be being displayed.
Not sure if I missed it, but I never see you set the delegate property in ConusViewController. That needs to be set to an instance of the object that is to be delegated to (the object that has dismissPopover implemented in it).