I have defined the protocol in Customer.h file which is shown below:
#class Customer;
#protocol CustomerDelegate <NSObject>
-(void) didSelectCustomer:(Customer *) customer;
#end
#interface Customer : NSObject
{
}
#property (nonatomic,copy) NSString *name;
#property (nonatomic,copy) NSString *occupation;
#end
The MasterViewController (left side) invokes the didSelectCustomer method as shown below:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
Customer *selectedCustomer = [customers objectAtIndex:[indexPath row]];
[self.delegate didSelectCustomer:selectedCustomer];
}
Now, I need to tell the DetailViewController (right side) to do something. The DetailViewController complies with the CustomerDelegate protocol.
#interface DetailViewController : UIViewController<UISplitViewControllerDelegate,CustomerDelegate>
{
}
-(void) didSelectCustomer:(Customer *)customer
{
NSLog(#"sssdasdasdasd");
}
The didSelectCustomer method is never invoked. I think I need to set the masterViewController.delegate = self but I am not sure where to set this thing up.
UPDATE 1:
I added the instance of MasterViewController inside the DetailViewController but it did not work:
- (void)viewDidLoad
{
[super viewDidLoad];
MasterViewController *master = [[MasterViewController alloc] init];
master.delegate = self;
}
SOLUTION:
In AppDelegate:
else
{
UISplitViewController *splitViewController = (UISplitViewController *) self.window.rootViewController;
splitViewController.delegate = [splitViewController.viewControllers lastObject];
UINavigationController *navigationController = [splitViewController.viewControllers lastObject];
// splitViewController.delegate = (id)navigationController.topViewController;
DetailViewController *detail =(DetailViewController *) [splitViewController.viewControllers lastObject];
UINavigationController *masterNavigationController = [splitViewController.viewControllers objectAtIndex:0];
MasterViewController *master = (MasterViewController *)masterNavigationController.topViewController;
master.delegate = detail;
}
You never explicitly declare yourself as the delegate to the Consumer class. Merely conforming to it won't cut it. Declare it in -viewDidLoad by creating an instance of Consumer, possibly like this:
-(void)viewDidLoad {
Consumer *consumer = [[Consumer alloc]init];
[consumer setDelegate:self];
}
You also don't declare a property for your delegate object in Consumer, so it can never actually be accessed. Do this first:
#class Customer;
#protocol CustomerDelegate <NSObject>
-(void) didSelectCustomer:(Customer *) customer;
#end
#interface Customer : NSObject
{
}
#property (nonatomic,copy) NSString *name;
#property (nonatomic,copy) NSString *occupation;
#property (weak) id <CustomerDelegate> delegate; //use assign or __unsafe_unretained if targeting <5.0.
#end
You can check if your class conforms to your protocol like so:
if (![delegate conformsToProtocol:#protocol(CustomerDelegate)]) {
[NSException raise:#"Delegate Exception"
format:#"Parameter does not conform to CustomerDelegate protocol at line %d", (int)__LINE__];
}
the split view controller's last object.
this object is return a UI navigation controller.
you know, then you can do yourself.
Related
Here is my situation. I have ViewController class A with a button that goes to TableViewController class B by doing the following.
- (void) goToClassB
{
ViewControllerB *viewController =
[[ViewControllerB alloc] initWithStyle:UITableViewStylePlain];
// Present view controller modally.
if ([self
respondsToSelector:#selector(presentViewController:animated:completion:)]) {
[self presentViewController:viewController animated:YES completion:nil];
} else {
[self presentModalViewController:viewController animated:YES];
}
}
I want to be able to have an array that can be accessed and edited by both class A and class B. How can I achieve this?
Create a Array variable in Class B like:
#interface classB:NSObject
{
NSMutableArray *arrayFromA;
}
#property (nonatomic, assign) NSMutableArray *arrayFromA;
Synthesize the variable.
And in this method pass the array like:
- (void) goToClassB
{
ViewControllerB *viewController = [[ViewControllerB alloc] initWithStyle:UITableViewStylePlain];
[viewController setArrayFromA:yourArray];
// Present view controller modally.
if ([self
respondsToSelector:#selector(presentViewController:animated:completion:)])
{
[self presentViewController:viewController animated:YES completion:nil];
}
else
{
[self presentModalViewController:viewController animated:YES];
}
}
Create a NSMutableArray in ViewControllerA and pass it to ViewControllerB after your allocation.
This can be achieve Creating NSMutableArray And And Make it in Property assign in one of the class
#property(nonatomic,assign) NSMutableArray *array;
I mention that you want edit by both so.You can use application delegation for sharing app level variable. Check this link.
Some code is here. In your app delegate class.
#interface YourDelegateClass:UIResponder
{
NSMutableArray *array;
}
#property (nonatomic, assign) NSMutableArray *array;
You can access that array from everywhere of your app class with this code
YourDelegateClass * delegate =[[UIApplication shareApplication]delegate];
yourclassa.array = delegate.array;
or yourclassb.array = delegate.array;
Note: your must alloc *delegate.array* on your prefer at class or your delegate.
Create NSMutable array in view1 set property
#property(nonatomic,assign) NSMutableArray *array;
Create same array in viewB and set property and
#property (nonatomic, assign) NSMutableArray *arrayB;
#Synthesize that
Now at the time call viewB set value of array of viewA to viewB like this
ViewControllerB *viewController = [[ViewControllerB alloc] initWithStyle:UITableViewStylePlain];
[viewController arrayB:array];
The simplest way would, just as others point out, be simply passing the array to B by setting a property, but one other option would be to let B have a weak back reference to A. Thus you're always using the same array. This could be useful if A and B are changing the array at the same time.
#interface ViewControllerA : UIViewController
#property (nonatomic, strong) NSArray *array;
#end
#interface ViewControllerB : UIViewController
#property (nonatomic, weak) ViewControllerA *viewControllerA;
#end
/* When you're creating the ViewControllerB, do this: */
...
viewController.viewControllerA = self;
...
/* Use the array (From ViewControllerB) */
- (void)doSomethingWithTheArray
{
self.viewControllerA.array = ...
}
I have to pass a UITextField value from one view to other views(2nd,3rd...views).Actually in my 3rd ViewController I have a scrollView and I have to display value on it .But UITextField value is not getting passed.It is returning null.Couldn't get what might be wrong?
THis is the code I am working with:
In ViewController1.m:
-(IBAction)butonclick:(id)sender{
ViewController2 *view2=[ViewController2 alloc];
view2.id=name.text;
ViewController3 *view3=[ViewController3 alloc];
view3.id=name.text;
[view2 release];
[view3 release];
}
IN ViewConroller2.h :
#interface ViewController2 : UIViewController {
NSString *id;
UIlabel *displayId;
}
In ViewController2.m :
- (void)viewDidLoad
{
self.displayId.text=self.id;
}
In ViewController3.h:
#interface ViewController2 : UIViewController {
NSString *id;
UIlabel *dispId;
}
In ViewController3.m :
- (void)viewDidLoad
{
self.dispId.text=self.id;
}
But here the id value is not passed to ViewController3.It is returning null ..Where I m going wrong?
You are passing the values without initializing.
ViewController2 *view2=[[ViewController2 alloc]init];
view2.id=name.text;
ViewController3 *view3=[[ViewController3 alloc]init];
view3.id=name.text;
If you want to use object globally within your app, you can declare it in the appDelegate.
In AppDelegate.h
#interface AppDelegate : NSObject <NSApplicationDelegate>
{
NSString *idGlobal;
}
#property (nonatomic, retain) NSString *idGlobal;
In AppDelegate.m
#synthesize idGlobal;
In ViewController1.m:
-(IBAction)butonclick:(id)sender{
appDelegate.idGlobal=name.text;
}
In ViewController2.m: and
In ViewController3.m:
AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
id=appDelegate.idGlobal;
Declare the string globally in the AppDelegate.h this will help in keeping the value of the string constant throughout the files. Also wherever you want to add the string or change its value or assign it import the AppDelegate.h .
Also check these links :-
passing NSString from one class to the other
Pass NSString from one class to another
I am just correcting the code you have written meanwhile the suggestions given above for using AppDelegate property is a good one.
The main problem with your code is that you are just declaring NSString object instead of making it a property. Check this:
-(IBAction)butonclick:(id)sender{
ViewController2 *view2=[ViewController2 alloc]init];
view2.str=name.text;
ViewController3 *view3=[ViewController3 alloc]init;
view3.str=name.text;
[view2 release];
[view3 release];
}
IN ViewConroller2.h :
#interface ViewController2 : UIViewController {
NSString *str;
UIlabel *displayId;
}
#property(nonatomic, retain) NSString* str; //Synthesize it in .m file
In ViewController2.m :
- (void)viewDidLoad
{
self.displayId.text=self.str;
}
In ViewController3.h:
#interface ViewController2 : UIViewController {
NSString *str;
UIlabel *dispId;
}
#property(nonatomic, retain) NSString* str; //Synthesize it in .m file
In ViewController3.m :
- (void)viewDidLoad
{
self.dispId.text=self.str;
}
I am not aware with your scenario but the most effective way of implementing such situations is using Delegates. Make a delegate of the class where your string is being set (ViewController1) and set delegate accordingly in your other view controllers.
I am building a utility application which shares data between main view and flip view. Actually, it is not exactly the flip view that's holding data, it's the custom view that's an instance of the flip view when it gets loaded. I have explained the specifics in my previous thread here, but I haven't got a solution yet. And I have redeveloped my code, hopefully this time I could make myself clear.
The general concept here is I create and store data in my main view, and pass it to the flip side view using the predefined delegate in the FlipViewController. Then in the FlipViewController, I store the data in my own delegate and pass it to the custom view which implements my own delegate method. The following is the main portions of the code.
MainViewController.m (only adopts <FlipsideViewControllerDelegate> protocol)
- (IBAction)showInfo:(id)sender {
FlipsideViewController *controller = [[FlipsideViewController alloc] initWithNibName:#"FlipsideView" bundle:nil];
controller.delegate = self;
controller.chart = data;
controller.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:controller animated:YES];
[controller release];
}
FlipsideViewController.h
#protocol FlipsideViewControllerDelegate;
#protocol ChartDelegate;
#interface FlipsideViewController : UIViewController {
id <FlipsideViewControllerDelegate> delegate;
id <ChartDelegate> delegate2;
DataModel *chart;
}
#property (nonatomic, assign) id <FlipsideViewControllerDelegate> delegate;
#property (nonatomic, assign) id <ChartDelegate> delegate2;
#property (nonatomic, retain) DataModel *chart;
- (IBAction)done:(id)sender;
#end
#protocol FlipsideViewControllerDelegate
- (void)flipsideViewControllerDidFinish:(FlipsideViewController *)controller;
#end
#protocol ChartDelegate <NSObject>
- (void)getParams:(DataModel *)dataModel;
#end
FlipsideViewController.m
#synthesize delegate, delegate2;
#synthesize chart;
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor viewFlipsideBackgroundColor];
if ([delegate2 respondsToSelector:#selector(getParams:)]) {
[delegate2 getParams:chart];
}
}
customDrawing.h
#interface customDrawing : UIView <ChartDelegate>{
DataModel *chartData;
}
#property (nonatomic, retain) DataModel *chartData;
#end
customDrawing.m
#synthesize chartData;
-(void)getParams:(DataModel *)dataModel{
chartData = dataModel;
}
It turns out the data didn't get passed to the chartData object in my custom view. HELP?
You are missing the fundamentals. I do not think you need delegates to achieve this task but here we go.
A protocol is like a contract. In you FlipsideViewController class you defined the protocol which essentially states if you conform to this protocol then you must implement this method.
How do you conform to a protocol?
In MainViewController the #interface will look something like this
#interface MainViewController : UIViewController <FlipsideViewControllerDelegate>
The fact that you have the protocol written in angled brackets means that you promise to conform to the protocol and therefore have to implement
- (void)flipsideViewControllerDidFinish:(FlipsideViewController *)controller;
in your MainViewController.m.
Now when MainNavigationController set's itself as the delegate (controller.delegate = self;) it finishes the link. This allows the FlipsideViewController to call
[delegate flipsideViewControllerDidFinish:self];
Which will call the method defined in MainViewController which dismisses the modal view controller.
You have defined a second protocol (you could have added the method to the first and then you would not have to adopt two protocols) and as others have pointed out you have not linked the classes up by doing
controller.delegate2 = self;
This would not solve your problem. You would still need to conform to the ChartDelegate by adding it to the declaration. Once you have done that you will still not be out of the water because the method is not correct.
Full solution - not using delegates as they are not really required here
MainViewController.h
#interface MainViewController : UIViewController <FlipsideViewControllerDelegate>
- (IBAction)showInfo:(id)sender;
#end
MainViewController.m
#implementation MainViewController
- (void)flipsideViewControllerDidFinish:(FlipsideViewController *)controller
{
[self dismissModalViewControllerAnimated:YES];
}
- (IBAction)showInfo:(id)sender
{
FlipsideViewController *controller = [[FlipsideViewController alloc] initWithNibName:#"FlipsideView" bundle:nil];
controller.delegate = self;
/*
* The labelText property is defined in the header for FlipsideViewController
* In this case this is the easiest way to get data from this controller to
* the controller we are about to display
*/
controller.labelText = #"WHAT EVER YOU WANT TO SEND"; // <---- sending data
controller.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:controller animated:YES];
[controller release];
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
#end
FlipsideViewController.h
#class FlipsideViewController;
#protocol FlipsideViewControllerDelegate
- (void)flipsideViewControllerDidFinish:(FlipsideViewController *)controller;
#end
#interface FlipsideViewController : UIViewController
/*
* These properties have been added. The label is used for displaying the text
* and needs to be hooked up in Interface builder
*
* The NSString is the property that is holding the data passed from MainViewController
*/
#property (nonatomic, retain) IBOutlet UILabel *testLabel;
#property (nonatomic, copy) NSString *labelText; from MainViewControlller
#property (nonatomic, assign) id <FlipsideViewControllerDelegate> delegate;
- (IBAction)done:(id)sender;
#end
FlipsideViewController.m
#implementation FlipsideViewController
#synthesize delegate = _delegate;
/*
* We need to synthesise out properties so we get our getters and setters created
*/
#synthesize testLabel = _testLabel;
#synthesize labelText = _labelText;
#pragma mark - View lifecycle
- (void)viewDidLoad
{
[super viewDidLoad];
/*
* This is called once the view is set up and all connections have been made in
* interface builder. Therefore we can now set the text of our test label
*/
self.testLabel.text = labelText;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
#pragma mark - Actions
- (IBAction)done:(id)sender
{
[self.delegate flipsideViewControllerDidFinish:self];
}
- (void)dealloc
{
/*
* Memory management for the ivars we added
*/
[_testLabel release];
[_labelText release];
[super dealloc];
}
#end
You have two properties: delegate and delegate2. You are assigning a value to delegate, but calling the method on delegate2 later.
You need to assign the delegate2 (your customDrawing class). You are only assigning the delegate.
In my application i have some view controllers and one objective c class ,how can i access the UI elemets of one view controller to change their values in objective class .
To explain further , i have a UILable *lab in the firstviewcontroller and just imported
#import "firstViewController.h"
in my customclass.m file and i am trying to do like this in one method of objective c class
firstViewController.lab.text=#"example";
( i know its not correct method but i am trying to explain what i am doing )
can any one please tell me how can i do that ?
First thing you need to do is grab a reference to the view controller you wish to operate on. One way to do this and have it available to other classes is to store a reference to it in a singleton object that you instantiate in your customclass.m. Specifically this is how this method works:
Define Singleton Object:
#import <Foundation/Foundation.h>
#interface MySingleton : NSObject {
MyViewController *myViewController;
}
#propery (nonatomic. retain) MyViewController *myViewController;
+(MySingleton*)sharedMySingleton;
#implementation MySingleton
#synthesize myViewController;
static MySingleton* _sharedMySingleton = nil;
+(MySingleton*)sharedMySingleton
{
#synchronized([MySingleton class])
{
if (!_sharedMySingleton)
[[self alloc] init];
return _sharedMySingleton;
}
return nil;
}
+(id)alloc
{
#synchronized([MySingleton class])
{
NSAssert(_sharedMySingleton == nil, #"Attempted to allocate a second instance of a singleton.");
_sharedMySingleton = [super alloc];
return _sharedMySingleton;
}
return nil;
}
-(id)init {
self = [super init];
if (self != nil) {
// initialize stuff here
}
return self;
}
#end
Whereever you instantiate your myViewController you do this:
#import "MySingleton.h"
MySingleton *sinlgeton = [MySingleton sharedMySingleton];
singleton.myViewController = myViewController;
Now in your CustomClass.m you do this:
#import "MySingleton.h"
MySingleton *sinlgeton = [MySingleton sharedMySingleton];
singleton.myViewController.lab.text = #"example"
As I said this is ONE WAY to do this. However, you most probably DO NOT want to access and change view controller properties in a custom class so you should really rethink why you are doing this at all.
As with most programming tasks there are several solutions and it depends on the situation.
You can have FirstViewController own the instance of the MyCustomClass and then pass itself.
#interface FirstViewController : UIViewController {
MyCustomClass *customClass_;
}
#end
#implementation FirstViewController
- (void)viewDidLoad {
[super viewDidLoad];
customClass_ = [[MyCustomClass alloc] init]
customClass_.firstViewController = self;
}
#end
#interface MyCustomClass : NSObject {
FirstViewController *firstViewController;
}
#property (nonatomic, assign) FirstViewController *firstViewController;
#end
This way MyCustomClass can access the properties of FirstViewController. If you don't want to give MyCustomClass access to all of FirstViewController you can use pass along the properties that MyCustomClass should know about.
#interface FirstViewController : UIViewController {
MyCustomClass *customClass_;
UILabel *lab;
}
#property (nonatomic, retain) IBOutlet UILabel *lab;
#end
#implementation FirstViewController
- (void)viewDidLoad {
[super viewDidLoad];
customClass_ = [[MyCustomClass alloc] init]
customClass_.lab = self.lab;
}
#end
#interface MyCustomClass : NSObject {
UILabel *lab;
}
#property (nonatomic, retain) IBOutlet UILabel *lab;
#end
It could very well be the case that it doesn't make sense for FirstViewController to be the owner of MyCustomClass. Perhaps it is the AppDelegate or some parent controller that have access to both instances.
#interface RandomParentClass : NSObject {
FirstViewController *firstViewController;
MyCustomClass *customClass:
}
#end
#implementation RandomParentClass
- (void)setUpController {
firstViewController = [[FirstViewController alloc] init];
customClass = [[MyCustomClass alloc] init];
customClass.lab = firstViewController.lab;
// or
customClass.firstViewController = firstViewController;
}
#end
I have an UIViewController named MainViewController
I have another UIViewController named LeftSharingViewController;
I would like to get and use the NSString from MainViewController in my LeftSharingViewController
I have a problem, I always get (null) instead of the NSString wanted value.
Here's my code and how does the NSString get it's value
MainViewController:
- (void)webViewDidFinishLoad:(UIWebView *)webView {
leftWebViewString = [NSString stringWithString:leftWebView.request.URL.absoluteString];
}
LeftSharingViewController.h:
#import <UIKit/UIKit.h>
#import "MainViewController.h"
#import <MessageUI/MessageUI.h>
#import <MessageUI/MFMailComposeViewController.h>
#class MainViewController;
#interface LeftSharingViewController : UIViewController <MFMailComposeViewControllerDelegate> {
MainViewController *mainViewController;
NSString *leftWebViewUrl;
}
#property (nonatomic, retain) MainViewController *mainViewController;
#property (nonatomic, retain) NSString *leftWebViewUrl;
#end
LeftSharingViewController.m:
#import "LeftSharingViewController.h"
#import "MainViewController.h"
#implementation LeftSharingViewController
#synthesize mainViewController;
#synthesize leftWebViewUrl;
- (void)viewWillAppear:(BOOL)animated {
self.leftWebViewUrl = self.mainViewController.leftWebViewString;
}
#pragma mark -
#pragma mark Compose Mail
-(void)displayComposerSheet
{
MFMailComposeViewController *mailPicker = [[MFMailComposeViewController alloc] init];
mailPicker.mailComposeDelegate = self;
[mailPicker setSubject:#"Check Out This Website!"];
[mailPicker setMessageBody:[NSString stringWithFormat:#"Take a look at this site:%#", leftWebViewUrl] isHTML:YES];
mailPicker.modalPresentationStyle = UIModalPresentationFormSheet;
[self presentModalViewController:mailPicker animated:YES];
[mailPicker release];
}
Thanks!
On your MainViewController, you are never retaining the NSString you create. You are using stringWithString:, which returns an autoreleased object.
You should either retain it, or (easier) change your code to use your accessor, which already retains, like this:
- (void)webViewDidFinishLoad:(UIWebView *)webView {
self.leftWebViewString = [NSString stringWithString:leftWebView.request.URL.absoluteString];
}
As a side note, if you are navigating from MainViewController to LeftSharingViewController, instead of "pulling" the data in LeftSharingViewController from MainViewController, I would do it the other way around:
In MainViewController, before displaying the view of LeftSharingViewController, I'd set the required properties.