I want to know how to pass values between views in popViewControllerAnimated .
Here is my scenario:
I have a view which contains tableview on selecting the cell we go to another view where i need to enter value in textbox and i click a button to go back to the previous view where i need to display the textbox value in the table view cell.
How can i do this ?
This what i have done:
NewContact *nc = [[NewContact alloc] initWithNibName:#"NewContact" bundle:nil];
// ...
// Pass the selected object to the new view controller.
nc.name=[firstName text];
//[self.navigationController pushViewController:nc animated:YES];
[self.navigationController popViewControllerAnimated:YES];
[nc release];
In ViewControllerB, declare delegate and set action for popViewControllerAnimated:
#interface ViewControllerB : UIViewController {
id delegate;
}
#property (nonatomic, retain) id delegate;
#synthesize delegate;
- (id) init ... {
self.navigationItem.leftBarButtonItem = [[[UIBarButtonItem alloc] initWithTitle:#"Back"
style:UIBarButtonItemStyleBordered
target:self
action:#selector(didBack:)] autorelease];
}
- (void) didBack:(id)sender {
if ([delegate respondsToSelector:#selector(setProperty:)]) {
[delegate setProperty:property];
}
[self.navigationController popViewControllerAnimated:YES];
}
In ViewControllerA, provide a function to set the local property and set delegate:
ViewControllerB controllerB = [[ViewControllerB alloc] init...];
[controllerB setDelegate:self];
[self.navigationController pushViewController:controllerB animated:YES];
[controllerB release];
You need to store value in one of the global variable for example you can declare in appDelegate file. See this post for that
If you are using UITextField then you can store value in above variable from UITextField in below delegate method.
- (BOOL)textFieldShouldReturn:(UITextField *)textField;
Hope this help.
You could use NSNotificationCenter for this, passing an object along with the call.
Howto: Send and receive messages through NSNotificationCenter in Objective-C?
Based on your requirement in your comment,
Say you navigate from ViewControllerA instance to ViewControllerB instance and you wish to call ViewControllerA's methods, you can do it like this,
ViewControllerA * viewControllerA = (ViewControllerA *)self.parentViewController.
[viewController methodToCall];
To use this to address the requirement in the question, you can use a property.
viewControllerA.name = firstName.text; // Bits from your code snippet
However in a table view I would expect you to have a mutable array powering the data source. You can refer to it, assuming that it is an property.
[viewControllerA.dataSourceArray addObject:firstName.text];
Related
so in my app delegate I am trying to present a modalViewController from a UITabBarController, by doing the following:
self.tabBarController = [[UITabBarController alloc] init];
LoginViewController* loginViewController = [[LoginViewController alloc] init];
loginViewController.delegate = self;
[self.tabBarController presentModalViewController:loginViewController animated:NO];
[loginViewController release];
and the delegate defined in the app delegate is:
- (void)userDidLogin:(LoginViewController *) loginViewController
{
NSLog(#"DELEGATE CALLED, DISMISSING");
[self.tabBarController dismissModalViewControllerAnimated:NO];
}
Here's my LoginViewController:
protocol LoginViewControllerDelegate;
#interface LoginViewController : UIViewController <MBProgressHUDDelegate>
{
id<LoginViewControllerDelegate> delegate;
}
#property (assign) id<LoginViewControllerDelegate> delegate;
#end
#protocol LoginViewControllerDelegate
- (void)userDidLogin:(LoginViewController *) loginViewController;
#end
The issue is that this (userDidLogin:(LoginViewController *) loginViewController) is never called... why is this?
I have called the following in my LoginViewController implementation and this is called
[self.delegate userDidLogin:self];
UPDATE:
I got the delegate called now. The issue now is that when I call [self.tabBarController dismissModalViewControllerAnimated:YES] it doesn't dismiss the modal view controller.
You didn't post any code from LoginViewController, but within that class's code you need to add the following lines when you are ready to dismiss it (perhaps when the user clicks the "Login" button and the login is successful).
if (delegate && [delegate respondsToSelector:#selector(userDidLogin:)])
[delegate performSelector:#selector(userDidLogin:) withObject:self];
UPDATE:
I think I understand what the issue is here. According to Apple's documentation, when you call presentModalViewController:animated: the method sets the value of the "modalViewController" property of UIViewController (in this case your UITabBar). However that property only maintains a weak reference to the modalViewController. That's important because you initialize the LoginViewController, pass it in to presentModalViewController:animated: and then you release it. Since presentModalViewController:animated: is not retaining a strong reference to the LoginViewController, the UITTabBar is unable to dismiss it later on. In fact I'm surprised what you have done is not resulting in an EXC_BAD_ACCESS crash. I suggest you remove the "[loginViewController release]" statement and instead release it after you call "[self.tabBarController dismissModalViewControllerAnimated:NO]"
hi everyone i am new to iphone development.
Actually i am trying with some sample app where i have a textField in the Viewcontroller and a Button,when i enter a string in the textfield and press the button it should display the same string in NextView.so can anyone help me out in doing this.
i worked with transition between one view to another view,but i need copy string from Viewcontroller1 to NextView
#ViewController1
-(IBAction)next
{
NextView *Nview = [[NextView alloc]initWithNibName:#"NextView" bundle:nil];
[self.view addSubview:Nview.view];
}
Set an ivar in your NextView called "newString" for example, then pass a string to that ivar form your first controller.
For Example, not tested (and this is one of many ways you can do this):
FirstView
NextView * next = [[NextView alloc] initWithNewString: myTextField.text];
[self.navigationController presentModalViewController: next animated: YES];
NextView
#synthesize newString
-(id)initWithNewString:(NSString*)someString
{
newString = someString;
return self;
}
Then throughout your NextView, just call upon newString wherever you want to get the value of the previous views textField.
-(IBAction)next
{
NextView *Nview = [[NextView alloc]initWithNibName:#"NextView" bundle:nil];
Nview.string_Object=string_to_copy;//declare string_Object in NextView.h
[self.view addSubview:Nview.view];
}
Try this:
In your first view while naviagting:
NextView *nav = [[NextView alloc] init];
nav.textFieldValue = textField.text;
[self.navigationController pushViewController:nav animated:YES];
And in your NextView's .h file create a property:
#property(nonatomic, retain) NSString *textFieldValue;
And in .m file synthesize it like:
#synthesize textFieldValue;
Now you can use textFieldValue in NextView class
P.S: Don't forget to release it :)
As you are a beginner, this will be a good guidance for you to understand the exact flow and it will make you learn how to pass values from one class to another.
Here is an approach (haven't tested, but should work)
Give your textField a tag value like
textField.tag = 1;
and in NextView access it like
UITextField *parentViewTextField = (UITextField*)[self.superview viewWithTag:1]
I have one view who calculates location and reverser geocode to get the zip code. Then it calls another view where I want to display weather results based on that zip code.
In the first view controller I do this once user clicks on the button to turn the page:
- (IBAction) showMyWeather : (id)sender {
WeatherApp *weather = [[WeatherApp alloc] initWithNibName:nil bundle:nil];
weather.zipcode = placemarkZip; //this one seems not to be doing the job
weather.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:weather animated:YES];
}
And at the WeatherApp I would like to read now zipcode, which is declared in this view controller .h:
#interface WeatherApp : UIViewController{
IBOutlet UIButton *done;
MKPlacemark *zipcode;
}
#property (nonatomic, retain) MKPlacemark *zipcode;
How can I use this code to transfer this zipcode to the WeatherApp? Thanks!
Yes, this is a fine way to pass information into your new object.
Alternatively, you could create a custom initializer for WeatherApp like
- (id)initWithZipCode:(NSString *)zip;
and then in the implementation file, it could be like this:
- (id)initWithZipCode:(NSString *)zip
{
self = [super init];
[self setZipcode:zip];
return self;
}
Finally, you could instantiate the class like so:
- (IBAction)showMyWeather:(id)sender
{
WeatherApp *weather = [[WeatherApp alloc] initWithZipCode:placemarkZip];
[weather setModalTransitionStyle:UIModalTransitionStyleFlipHorizontal];
[self presentModalViewController:weather animated:YES];
[weather release]; // No longer needed with ARC... just sayin'
}
Finally, if you're going to continue to pass in information as you do above, I'd question why you're using initWithNibName:bundle:. If you're just going to pass nil to both, why not just use [[WeatherApp alloc] init]?
I have two view controllers, firstViewController and secondViewController. I am using this code to switch to my secondViewController (I am also passing a string to it):
secondViewController *second = [[secondViewController alloc] initWithNibName:nil bundle:nil];
second.myString = #"This text is passed from firstViewController!";
second.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
[self presentModalViewController:second animated:YES];
[second release];
I then use this code in secondViewController to switch back to the firstViewController:
[self dismissModalViewControllerAnimated:YES];
All of this works fine. My question is, how would I pass data to the firstViewController? I would like to pass a different string into the firstViewController from the secondViewController.
You need to use delegate protocols... Here's how to do it:
Declare a protocol in your secondViewController's header file. It should look like this:
#import <UIKit/UIKit.h>
#protocol SecondDelegate <NSObject>
-(void)secondViewControllerDismissed:(NSString *)stringForFirst
#end
#interface SecondViewController : UIViewController
{
id myDelegate;
}
#property (nonatomic, assign) id<SecondDelegate> myDelegate;
Don't forget to synthesize the myDelegate in your implementation (SecondViewController.m) file:
#synthesize myDelegate;
In your FirstViewController's header file subscribe to the SecondDelegate protocol by doing this:
#import "SecondViewController.h"
#interface FirstViewController:UIViewController <SecondDelegate>
Now when you instantiate SecondViewController in FirstViewController you should do the following:
// If you're using a view controller built with Interface Builder.
SecondViewController *second = [[SecondViewController alloc] initWithNibName:"SecondViewController" bundle:[NSBundle mainBundle]];
// If you're using a view controller built programmatically.
SecondViewController *second = [SecondViewController new]; // Convenience initializer that uses alloc] init]
second.myString = #"This text is passed from firstViewController!";
second.myDelegate = self;
second.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
[self presentModalViewController:second animated:YES];
[second release];
Lastly, in the implementation file for your first view controller (FirstViewController.m) implement the SecondDelegate's method for secondViewControllerDismissed:
- (void)secondViewControllerDismissed:(NSString *)stringForFirst
{
NSString *thisIsTheDesiredString = stringForFirst; //And there you have it.....
}
Now when you're about to dismiss the second view controller you want to invoke the method implemented in the first view controller. This part is simple. All you do is, in your second view controller, add some code before the dismiss code:
if([self.myDelegate respondsToSelector:#selector(secondViewControllerDismissed:)])
{
[self.myDelegate secondViewControllerDismissed:#"THIS IS THE STRING TO SEND!!!"];
}
[self dismissModalViewControllerAnimated:YES];
Delegate protocols are EXTREMELY, EXTREMELY, EXTREMELY useful. It would do you good to familiarize yourself with them :)
NSNotifications are another way to do this, but as a best practice, I prefer using it when I want to communicate across multiple viewControllers or objects. Here's an answer I posted earlier if you're curious about using NSNotifications: Firing events accross multiple viewcontrollers from a thread in the appdelegate
EDIT:
If you want to pass multiple arguments, the code before dismiss looks like this:
if([self.myDelegate respondsToSelector:#selector(secondViewControllerDismissed:argument2:argument3:)])
{
[self.myDelegate secondViewControllerDismissed:#"THIS IS THE STRING TO SEND!!!" argument2:someObject argument3:anotherObject];
}
[self dismissModalViewControllerAnimated:YES];
This means that your SecondDelegate method implementation inside your firstViewController will now look like:
- (void) secondViewControllerDismissed:(NSString*)stringForFirst argument2:(NSObject*)inObject1 argument3:(NSObject*)inObject2
{
NSString thisIsTheDesiredString = stringForFirst;
NSObject desiredObject1 = inObject1;
//....and so on
}
I could be way out of place here, but I am starting to much prefer the block syntax to the very verbose delegate/protocol approach. If you make vc2 from vc1, have a property on vc2 that you can set from vc1 that is a block!
#property (nonatomic, copy) void (^somethingHappenedInVC2)(NSString *response);
Then, when something happens in vc2 that you want to tell vc1 about, just execute the block that you defined in vc1!
self.somethingHappenedInVC2(#"Hello!");
This allows you to send data from vc2 back to vc1. Just like magic. IMO, this is a lot easier/cleaner than protocols. Blocks are awesome and need to be embraced as much as possible.
EDIT - Improved example
Let's say we have a mainVC that we want to present a modalVC on top of temporarily to get some input from a user. In order to present that modalVC from mainVC, we need to alloc/init it inside of mainVC. Pretty basic stuff. Well when we make this modalVC object, we can also set a block property on it that allows us to easily communicate between both vc objects. So let's take the example from above and put the follwing property in the .h file of modalVC:
#property (nonatomic, copy) void (^somethingHappenedInModalVC)(NSString *response);
Then, in our mainVC, after we have alloc/init'd a new modalVC object, you set the block property of modalVC like this:
ModalVC *modalVC = [[ModalVC alloc] init];
modalVC.somethingHappenedInModalVC = ^(NSString *response) {
NSLog(#"Something was selected in the modalVC, and this is what it was:%#", response);
}
So we are just setting the block property, and defining what happens when that block is executed.
Finally, in our modalVC, we could have a tableViewController that is backed by a dataSource array of strings. Once a row selection is made, we could do something like this:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
NSString *selectedString = self.dataSource[indexPath.row];
self.somethingHappenedInModalVC(selectedString);
}
And of course, each time we select a row in modalVC, we are going to get a console output from our NSLog line back in mainVC. Hope that helps!
hmm, look for the notification centre and pass back info in a notification. here is apples take on it
- I take this approach personally unless any one has any other suggestions
Define a delegate protocol in the second view controller and make the first one the delegate of the second.
This class is a subclass of UITabBarViewController.
In my init parent view controller file I have this:
UIBarButtonItem *button1 = [[UIBarButtonItem alloc]
initWithTitle:#"Button1"
style:UIBarButtonItemStyleBordered
target:self
action:#selector(button1:)];
self.navigationItem.rightBarButtonItem = button1;
[button1 release];
And the method:
-(IBAction)button1:(id)sender {
if (self.nvc == nil) {
ChildViewController *vc = [[ChildViewController alloc] init];
self.nvc = vc;
[vc release];
}
[self presentModalViewController:self.nvc animated:YES];
I want to get an value from the parentviewcontroller in my childviewcontroller class, which also is a UITabBarViewController subclass.
How do I do this, I have tried several hours, and I only get a nil-reference.
The object I want to get(which is a property in the parent) is a NSString.
Thanks in advance
The cleanest way would probably be to create a ChildViewControllerDelegate protocol that the parent view controller implements. This is a common idiom in iOS development.
#protocol ChildViewControllerDelegate
- (NSString *)getSomeNSString;
#end
Then you should make ChildViewController have this delegate as an instance variable and be assignable via a property
#property (nonatomic, assign) id<ChildViewControllerDelegate> delegate;
Now from within ChildViewController you can use this delegate to access methods on the delegate which in your case will be ParentViewController. This will allow you to retreive the string you want.
[delegate getSomeNSString]
This may seem like a lot of work for something simple but it avoids the problems inherit with storing a back reference from ChildViewController to its parent ParentViewController.
There are a lot of ways to do this. The easiest would be to add a property to ChildViewController that points to your parent view controller. You could call it delegate. Then the method will look like:
-(IBAction)newbuilding:(id)sender {
if (self.nvc == nil) {
ChildViewController *vc = [[ChildViewController alloc] init];
vc.delegate = self;
self.nvc = vc;
[vc release];
}
[self presentModalViewController:self.nvc animated:YES];
}
Then from the ChildViewController instance you can access self.delegate.someProperty.
There are also ways to get the parent view controller without your own explicit reference (typically self.tabBarController, self.navigationController depending on context), but the above method is fool-proof, understandable and easy to debug.