//
// MyGameViewController.h
//
#import < UIKit/UIKit.h >
#import "SecondViewController.h"
#interface MyGameViewController : UIViewController {
IBOutlet SecondViewController *secondViewController;
}
-(IBAction)goToSecondView;
#end
//
// MyGameViewController.m
//
#import "MyGameViewController.h"
#implementation MyGameViewController
-(IBAction)goToSecondView{
[self presentModalViewController:secondViewController animated:YES];
}
//
// MyGameView.h
//
#import < UIKit/UIKit.h >
#import "Sprite.h"
#interface MyGameView : UIView {…}
Currently I have implemented a button on the MyGameView.xib to invoke the secondViewController view and it works. But I want the secondViewController get invoked by programming inside MyGameView.m when there is interruption, not by pressing a button. Therefore, I think there are 2 approaches:
a) Either make the goToSecondView method available to MyGameView.m
b) Implement all the code in MyGameViewController.h and MyGameViewController.m to MyGameView.m.
Issues:
1) When tried to make a) happen, I have to make goToSecondView method starting with (void), not (IBAction). But then how to invoke it in MyGameView.m?
2) I tried to do b) and implemented all code to MyGameView.m. But presentModalViewController is a method of ViewController and does not work in UIView. So what is the solution?
As you stated, you can't call presentModalViewController in a UIView class. This seems like a great opportunity to use a delegate. You could do something along the lines of:
In MyGameView.h
#protocol MyGameViewDelegate
- (void)showSecondView;
#end
#interface MyGameView {
}
#property (nonatomic, assign) id <MyGameViewDelegate> delegate;
...
#end
In MyGameView.m, when you need to show the second view:
[self.delegate showSecondView];
In MyGameViewController.h:
#import "MyGameView.h"
#interface MyGameViewController : UIViewController <MyGameViewDelegate> {
...
In MyGameViewController.m:
#pragma mark MyGameViewDelegate methods
- (void)showSecondView {
[self goToSecondView];
}
Note that you'll also need to set MyGameViewController to be the delegate of MyGameView. You could do that in Interface Builder, or in code, depending on where you create the two objects.
To do it in code, for example in the MyGameViewController.h viewDidLoad method:
myGameView.delegate = self;
Related
I am a newbie to iPhone development and have some basic questions to ask about protocols and delegates. I have two view controllers: view controller and viewcontroller2nd. I have UITextField in one of them and would like to type something (like a name) in it and in the viewcontroller2nd, I have a UILabel and i would like it to appear Hello, name when the UITextField is changed.
I am following this video: http://www.youtube.com/watch?v=odk-rr_mzUo to get the basic delegate to work in a single view controller.
I am using protocols to implement this:
SampleDelegate.h
#import <Foundation/Foundation.h>
#protocol ProcessDelegate <UITextFieldDelegate>
#optional
- (BOOL)textFieldShouldReturn:(UITextField *)textField;
#end
#interface SampleDelegate : NSObject
{
id <ProcessDelegate> delegate;
}
#property (retain) id delegate;
#end
SampleDelegate.m
#import "SampleDelegate.h"
#implementation SampleDelegate
#synthesize delegate;
- (BOOL)textFieldShouldReturn:(UITextField *)textField{
lbl.text = [NSString stringWithFormat:#"Hello, %#",txtField.text];
[txtField resignFirstResponder];
}
#end
ViewController.h
#import <UIKit/UIKit.h>
#import "SampleDelegate.h"
#interface ViewController : UIViewController <ProcessDelegate>
{
IBOutlet UITextField *txtField;
}
#end
Viewcontroller.m
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
ViewController2nd.h
#import <UIKit/UIKit.h>
#interface ViewController2nd : UIViewController <ProcessDelegate> {
IBOutlet UILabel *lbl;
}
#end
and ViewController2nd.m is standard code from Xcode.
My question is how do i link my delegate function to my viewcontroller and viewcontroller2nd to get it working?
Pardon me if the question is stupid.. Need some guidance. Do point me any other mistakes that i am doing as well.. Thanks..
Your delegation is a bit... Off.
Firstly: Don't override UIKit delegate methods through protocol inheritance. It's pointless. Why not just make your class conform to the specified delegate in the first place?
#protocol ProcessDelegate //No more protocol inheritance!
//...
#end
Secondly: When an object has defined a protocol, a valid instance of that object must be in use by its delegate (or at least passed to it). So, anything that wants to be the delegate of SampleDelegate (really a bad name for a class, by the way) would initialize a valid SampleDelegate object, and call -setDelegate: as though it were any other property.
//#import "SampleDelegate"
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
//make this a property, so it isn't crushed when the function exits.
SampleDelegate *myDelegateObject = [[SampleDelegate alloc]init];
[myDelegateObject setDelegate:self]; //conform to the delegate
}
Thirdly: You don't actually define any delegate methods! What's the point of delegation if there's nothing to delegate!l
#protocol ProcessDelegate
-(void)someMethod;
#end
Fourth, and most important: Never, ever, ever, ever use the retain, or strong storage specifiers with a delegate! Delegate objects are supposed to be weak or assign to prevent nasty retain cycles.
#property (assign, nomatomic) id delegate;
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'm a relatively new iPhone developer and am making great progress building my 2nd iPhone app. In the app I'm building now I'm doing some code separation with some protocols and delegates so that I car re-use some of my code in a variety of places throughout my code.
Here's what I want to happen:
CITRootViewController creates an instance of a CITReportCreator class, passing itself as a property so that the reportCreator can open additional view controllers and such.
CITReportCreator class is declared as implementing the CITImageCaptureDelegate protocol, which is declared in the CITImageCaptureViewController file.
CITImageCaptureViewController defines the delegate protocol and has a method that passes back data and references to the child view controller so that CITReportCreator can interact with it's data, close the related XIB, etc.
I believe I'm getting the delegate and protocol established correctly, and verified that my 'delegate' object still contains data when it is called, but I'm getting a EXC_BAD_ACCESS method when my view controller tries to pass data back to the delegate in this line of code:
[self.delegate childViewControllerDidFinish:self];
Here's a good portion of the rest of my code. I had this working by using CITRootViewController as my delegate instead of the CITReportCreator class, but now that I'm separating the code, something has broke.
CITReootViewController.m (the view controller that calls the Report Creator)
//create a nrew report
-(IBAction)createReport:(id)sender {
CITReportCreator *report = [CITReportCreator alloc];
[report createNewReport:self];
}
CITReportCreator.h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import "CITImageCaptureViewController.h"
#interface CITReportCreator : NSObject <CITImageCaptureDelegate>
#property (strong, nonatomic) NSArray *imageList;
#property (nonatomic) NSInteger imageIndex;
-(int) createNewReport:(UIViewController *)parent ;
//Delegate Methods
-(void) childViewControllerDidFinish:(UIViewController*)viewController;
#end
And CITReportCreator.m
#import "CITReportCreator.h"
#implementation CITReportCreator
{
UIViewController *parentController;
}
#synthesize imageList;
#synthesize imageIndex;
-(int) createNewReport:(UIViewController *)parent
{
//store a reference to the parent view controller
parentController = parent;
// init code....
//head to the first image capture view
[self startImageCapture];
return 0;
}
-(int)startImageCapture
{
//pull the image name from the array of images
NSString *imageName = [imageList objectAtIndex:imageIndex];
//prep the image capture controller
CITImageCaptureViewController *capture = [[CITImageCaptureViewController alloc] initWithNibName:#"CITImageCaptureViewController" bundle:nil];
//Assign the capture controller's delegate
capture.imageName = imageName;
capture.delegate = self;
//Display the capture controller
[parentController presentModalViewController:capture animated:YES];
return 0;
}
//a break point set here never gets hit.
-(void) childViewControllerDidFinish:(UIViewController*)viewController;
{
[viewController dismissModalViewControllerAnimated:YES];
}
#end
And finally, the CITImageCaptureViewControllers
CITImageCaptureViewController.h
#import <UIKit/UIKit.h>
#protocol CITImageCaptureDelegate <NSObject>
-(void) childViewControllerDidFinish:(UIViewController*)viewController;
#end
#interface CITImageCaptureViewController : UIViewController
{
id<CITImageCaptureDelegate> delegate;
}
#property (nonatomic,assign) id<CITImageCaptureDelegate> delegate;
#property (nonatomic, assign) NSString *imageName;
//continue button pressed method
-(IBAction)continueButtonPressed:(id)sender;
#end
And the .m file
#import "CITImageCaptureViewController.h"
#interface CITImageCaptureViewController ()
#end
#implementation CITImageCaptureViewController
#synthesize navItem;
#synthesize imageName;
#synthesize delegate = _delegate; //i think this may be part of the problem
//cutting out initWithNibName, viewDidLoad, etc...
- (IBAction)continueButtonPressed:(id)sender
{
[self.delegate childViewControllerDidFinish:self];
}
#end
I find nothing with delegates and protocols all that simple, but I'm guessing I'm missing a small change somewhere. Can you help me head in the right direction?
I am trying to call an action (changeMainNumber) in a main view controller from a modal view controller. The action should change the UILabel mainNumber to 2. In ViewController.h, I have:
#import <UIKit/UIKit.h>
#interface ViewController : UIViewController {
IBOutlet UILabel *mainNumber;
}
#property (nonatomic, retain) UILabel *mainNumber;
-(IBAction)changeMainNumber;
ViewController.m:
#import "ViewController.h"
#implementation ViewController
#synthesize mainNumber;
- (IBAction)changeMainNumber:(id)sender {
mainNumber.text = #"2";
}
The next view controller is the modal view controller.
ModalViewController.h:
#import <UIKit/UIKit.h>
#class ViewController;
#interface ModalViewController : UIViewController {
}
-(IBAction)callChangeMainNumber:(id)sender;
and ModalViewController.m:
#import "ModalViewController.h"
#implementation ModalViewController
- (IBAction)callChangeMainNumber {
ViewController *viewController = [[ViewController alloc] init];
[viewController changeMainNumber];
}
With this setup the app keeps crashing when callChangeMainNumber is called and I can't figure out what is wrong. Any help you can provide is appreciated!
The code you posted from your ModalViewController is not referencing your ViewController. You are creating a new one in your code. The best solution to your problem would be to make your ViewController a delegate to the ModalViewController.
So in your ModalViewController.h file you should have this code above your #implementation.
#protocol ModalViewControllerDelegate
- (void)shouldChangeMainNumber;
#end
Then in your #implementation of the header have:
#property (nonatomic,assign)IBOutlet id <ModalViewControllerDelegate> delegate;
Now in the .m file where you have your IBAction method, tell the delegate that you want it to change the main number.
- (IBAction)callChangeMainNumber {
[self.delegate shouldChangeMainNumber];
}
Then in your ViewController.m file you need to set yourself as the delegate of the ModalViewController, usually in viewDidLoad is a good place to put it. So create a property in your header for the ModalViewController first and synthesize it, then add this to viewDidLoad.
self.modalViewController.delegate = self;
and finally you need to implement the delegate method in your .m file somewhere
- (void)shouldChangeMainNumber {
mainNumber.text = #"2";
}
Coding against UIKit for iPhone.
Setup, with relevant detail:
SomeView.h:
#import <UIKit/UIKit.h>
#interface SomeView : UIView {
SomeObject *myObject;
}
#property (assign) SomeObject *myObject;
-(void) doSomething;
#end
SomeView.m:
#import "SomeView.h"
#implementation SomeView
#synthesize myObject;
- (void)doSomething {
NSLog(#"doing something");
}
- (void) drawRect:(CGRect)rect {
// drawing is based on myObject
}
#end
Controller.h:
#import <UIKit/UIKit.h>
#import "SomeView.h"
#interface Controller : NSObject {
IBOutlet UIView *someView;
}
#end
Controller.m:
#import "Controller.h"
#implementation Controller
-(void)awakeFromNib {
[someView doSomething];
[someView setSomeObject:someObject];
}
#end
I am instantiating the controller object in Interface Builder, and SomeView is the class of one of my custom UIViews in my app's main window.
Now, the questions:
1) when I run the above, I get warnings for both lines: "Warning: 'UIView may not respond to 'doSomething'" and similar warning for setSomeObject. Why? (The code actually seems to work, but I don't like seeing the warnings.)
2) is this the right way of doing things? What I am really after, is making SomeView aware of someObject, so that when drawRect for SomeView is called, it can change its behavior based on current state of someObject. I don't need to have the object directly in SomeView; I could have it in the controller, but the view still needs some information from it that may change at runtime.
You declared someView as an instance of UIView, but doSomething is a method of SomeView. So it is correct — the class you told the compiler that the variable points to does not respond to that message. If you don't want warnings, you'll have to make it a SomeView * instead of a UIView *.
Otherwise, your general architecture looks OK to me.