I have application
I want a button to open another screen with done button
after click this button a data be transfered from the current screen to the previous one
like opening options screen , how to let the main view know the changes be done on this subview
Best regards
You can use properties for this.
Create a property in the second class: .h file
#interface DetailViewController : UIViewController {
NSString *head;
}
#property(nonatomic,retain)NSString *head;
#end
in .m file
#synthesize head;
Now in your firstviewcontroller or first class
if (dt==nil) {
DetailViewController *d = [[DetailViewController alloc]initWithNibName:#"Detailview" bundle:nil];
self.dt = d;
[d release];
}
dt.head=itemsum;
[self.navigationController pushViewController:self.dt animated:YES];
Suppose you have to pass NSString to other class then declare one Nsstring in second class and make accessor method for nsstring and then call this code from first view controller
yournextviewcontroller *viewcontroller = [[yournextviewcontroller alloc] initWithNibName:#"yournextviewcontroller" bundle:nil];
viewcontroller.Stringname = name;
[self.navigationController viewcontroller:evernotebook animated:YES];
You can take UIView as IBOutlet in the same ViewController. Show that view with click on Button like
IBOutlet UIView *yourAnotherScreenView; //Bind this to your view in XIB file.
[self.view addSubView:yourAnotherScreenView];
[self.view bringSubViewtoFront:yourAnotherScreenView];
Take Done button on the view and wireup the action event in the same controller and do the necessary stuff as required.
Use the simple delegate concept of Objective-C .
Check very simple answers in the below post for using delegate in Objective-C .
How do I set up a simple delegate to communicate between two view controllers?
Related
I have an app in which I am loading variable view controllers depending on where the user is in the app. This is my code.
-(IBAction)buttonPressed:(id)sender;{
if (mission <1) {
gameViewController *detailViewController = [[gameViewController alloc] initWithNibName:#"gameViewController" bundle:nil];
[self.navigationController pushViewController:detailViewController animated:YES];
detailViewController.which2 = which;
}
else if (mission > 0) {
NSString *viewController = #"gameViewController";
NSString *missionViewController = [viewController stringByAppendingString:missionNo];
Class controllerClass = NSClassFromString (missionViewController);
id detailViewController = [[controllerClass alloc] initWithNibName:#"gameViewController" bundle:nil];
NSLog(#"missionViewController;%#",missionViewController);
[self.navigationController pushViewController:detailViewController animated:YES];
detailViewController .which2 = which;
}
}
everything work great except I want to pass a string from the first view controller to the second view controller which ever one that may be.
As you can see I have put in the code just above detailViewController.which2 = which;
I have created the property and synthesized NSString *which in my first view controller and NSString *which2 in all the subsequent view controllers. in the first instance where mission is <1 everything works ok and NSLog shows the string being passed. However with the second detailViewController (which is the variable view controller) I get the error Property 'which2' not found on object of type"_strong id' Does anyone have any suggestion on how to resolve this?
the other viewControllers are gameViewController1, gameViewController2, etc. Each is rather long and complex. But they all load into the same xib file gameViewController. There is a UIlabel that update to one higher once the user finishes that gameView so they can go on the the next on in the series or go back to the main menu. If they go back to the main menu the number is added to "gameViewController" so the correct one is loaded. So I can't specify which view controller is going to load since it depends on the user's place. Thus the missionViewController with the # of mission added to load the correct view controller. Each of the subsequent view controllers has a which2 created and synthesized. What if we pretend that all subsequent view controllers just had a UILabel that is going to display the string "which2 in it. All I want to do is pass the string "which" to the next viewController (whichever one that is) as "which2".
Dynamic binding allows you to send messages to an id as long as the selector exists in the project, but dot-syntax is not allowed.
Changing
detailViewController.which2 = which;
to
[detailViewController setWhich2:which];
should suppress the warning.
write this : `detailViewController .which2 = which;
just before you push navigation controller.`
UPDATE:
Use Protools to update the value.
#protocol MissionProtocol
#required
-(void) updateValue:(NSSTring*) value;
#end
Implement the protocols in your ViewControllers. i.e.
#interface MissionViewController:UIViewController<MissionProtocol>
....
#end
In your implementation file, implement the method updateValue.
-(void) updateValue:(NSString*) value
{
self.which2=value;
}
Then change your original code to:
NSString *viewController = #"gameViewController";
NSString *missionViewController = [viewController stringByAppendingString:missionNo];
Class controllerClass = NSClassFromString (missionViewController);
id<MissionProtocol> detailViewController = [[controllerClass alloc] initWithNibName:#"gameViewController" bundle:nil];
[detailViewController updateValue:which];
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.
I have a UITableView in a UINavigationController. On the navigation bar I have a button called add. When this button is pressed it presents a UIPopoverController, where user can input data to be added as a new row/cell in the UITableView. My issue is how can I add a new cell to the UITableView from the UIPopover? Do I pass in the array data to the UIPopOver root controller?
There are two solutions to this that I'm aware of. One would be to send a notification from the popover to the root controller and apply the necessary code to update the tableView in the handleNotification method.
The other, one that I personally use, is to set up a delegate protocol for the popover. You'll have to set it up something like this:
#protocol PopoverDelegate
- (void)addNewCell; // you can add any information you need to pass onto this if necessary such as addNewCellWithName:(NSString *)name, etc.
#end
#interface MyPopoverViewController..... {
id <PopoverDelegate> delegate;
// the rest of your interface code;
}
#property (nonatomic, retain) id delegate;
// any other methods or properties;
#end
Then in your root view controller header file, you need to add the delegate
#interface RootViewController .... <PopoverDelegate> {
Then in your root view controller implementation file, assign the popover delegate when you instantiate it. For example:
MyPopoverViewController *vc = [[MyViewController alloc] init];
vc.delegate = self; // this is where you set your protocol delegate
myPopover = [[UIPopoverController alloc] initWithContentViewController:vc];
myPopover.delegate = self;
[vc release];
Finally, you'll add your protocol method somewhere in the code
- (void)addNewCell {
// do what you want with the tableView from here
}
Sorry that's a bit long. I just wanted to make sure I was thorough. Hope it helps
I have an UITabBarController with two tabs:
UINavigationController
OptionsViewController : UIViewController
How can I reach data (ie. UILabel.text) set in OptionsViewController, in a new added modal View which has been invoked from UINavigationController?
Edit1:
Scenario: After launching app I select the second tab bar called "Options" where I fill up a textField. The label is set to value from textField. Next I select first tab bar called "Main" where I have a button. I click the button and new modal View appears. In this new modal View I'd like to show the value from textField
I love MVC, but I'm not an absolute purist to the point of hurting yourself to accomplish a fairly trivial task, so the answers you've gotten here are good and useful. However, by creating an ivar to refer back to a specific type such as a label or other view controller, you are coupling things together that aren't necessary to couple. What you could do instead is make your first tab view controller a delegate of your second tab view controller. So do something like this in your app delegate.
OptionsViewController *optionsViewController = // ... get this from the tab view
FirsTabViewController *firstTabViewController = // ... same here
[optionsViewController setDelegate:firsTabViewController];
Which means that you need an ivar in your OptionsViewController:
#property (assign) id delegate;
Then, when whatever event you want to trigger the change occurs in your options view controller, see if the delegate can respond to a selector you've named. For example:
- (void)someEventHappenedLikeTyping:(id)sender;
{
if ([delegate respondsToSelector:#selector(setOptionsString:)]
[delegate performSelector:#selector(setOptionsString:) withObject:[label text]];
}
Notice you never specified any specific object types. You just check to see if the delegate (which was declared as id) can respond to that selector. If it can, it does what it's told and just is silent otherwise.
For this to work, you need an ivar for the optionsString in your FirstTabViewController and so it would be declared in the header as:
#property (copy) NSString *optionsString;
and then #synthesize it in the .m. This causes -setOptionsString to become a valid selector that will get called in the -someEventHappenedLikeTyping method.
Anyhow, now, if you ever need to to change which view controller references which, you don't have to go into the header and change the type of ivar referenced. You simply need to implement the selector (this is known as an informal protocol, by the way) in the view controller that is a delegate of your options view controller.
Just some food for thought there. Hope that helps. There is further de-coupling that could be done in the code I've added, but again it may be overkill for such a simple task. Let me know if you need clarification or want to understand what I mean by further decoupling.
Best regards,
p.s. Sometimes needing to share data between two tab bar view controllers, means you have a design flaw. If you are wanting to store preferences from your options view, you should just call
[[NSUserDefaults standardUserDefaults] setObject:[label text] forKey:#"option1"];
[[NSUserDefaults standardUserDefaults] synchronize];
Then you can pull from the NSUserDefaults back in your main tab with;
NSString *option1 = [[NSUserDefaults standardUserDefaults] objectForKey:#"option1"];
// Do something with option1
In your OptionsViewController, create a property:
#property (nonatomic, retain) UILabel *mylabel;
then after creating your OptionsViewController, but before displaying it, set the mylabel property. (Or perhaps you just want the text, so you can use an NSString* property.)
Edit:
So you probably want to do something like this:
OptionsViewController *vc = [[OptionsViewController alloc] init];
vc.mylabel = mySomethingLabel;
[self presentModalViewController:vc animated:YES];
So after creating the object, you set the property, and then you display the view controller.
I usually set IBOutlets in each of my viewcontrollers which point to the other controller.
So if I had view controllers A and B. A has an IBOutlet to B and B to A. Then whenever I want to access anything in B from A i just use a dot operator on B.
In your example UINavigationController would #include "OptionsViewController.h" and have an ivar IBOutlet OptionsViewController * ovc (which is set in IB) and then any instance variable from your options view controller can be referenced as ovc.UILabel.text from the navigation controller. This process can be reversed to access values from your navigation controller in your options view controller.
Example Navigation Controller (.h):
#include "OptionsViewController.h"
#interface UINavigationController // (whatever the name of this class is)
{
OptionsViewController * ovc;
}
#property (nonatomic, retain) IBOutlet OptionsViewController * ovc;
#end
Example OptionsViewController.h:
#interface OptionsViewController
{
UILabel * label;
}
#property (nonatomic, retain) IBOutlet UILabel * label;
#end
Then from UINavigationController (.m) you can just write ovc.label.text to access the text.
I have an easy way to access data between views. Let's try. You have two views named view1 and view2, you can define a View *vc1 property in view2.h, set the vc1 point to view1, when pop the view2, like this:
view1.m
//here pop out view1 code
View2 *view2 = [[View2 alloc] initWithNibName:#"View2" bundle:[NSBundle mainBundle]];
[self.navigationController pushViewController:view2 animated:YES];
view2.vc1 = self; //transfer view1 instance to view2，use vc1 you may handle view1 in view2 directly
[view2 release];
view2.h
#import "view1.h"
#property (nonatomic, retain) IBOutlet View1 *vc1; //here you could name it as view1 as well :)
view2.m
vc1.lblTable.text = #"ok"; //you'll see "ok" in view1
[self.navigationController popViewControllerAnimated:YES]; //navigate to view1
//dont forget release vc1
I need to pop up a quick dialog for the user to select one option in a UITableView from a list of roughly 2-5 items. Dialog will be modal and only take up about 1/2 of screen. I go back and forth between how to handle this. Should I subclass UIView and make it a UITableViewDelegate & DataSource?
I'd also prefer to lay out this view in IB. So to display I'd do something like this from my view controller (assume I have a property in my view controller for DialogView *myDialog;)
NSArray* nibViews = [[NSBundle mainBundle] loadNibNamed:#"DialogView" owner:myDialog options:nil];
myDialog = [nibViews objectAtIndex:0];
[self.view addSubview:myDialog];
problem is i'm trying to pass owner:myDialog which is nil as it hasn't been instantiated...i could pass owner:self but that would make my view controller the File's Owner and that's not how that dialog view is wired in IB.
So that leads me to think this dialog wants to be another full blown UIViewController... But, from all I've read you should only have ONE UIViewController per screen so this confuses me because I could benefit from viewDidLoad, etc. that come along with view controllers...
Can someone please straighten this out for me?
There is no such thing as a view controller being on the screen; its view is on the screen. With that said, you can present as many views as you want on the screen at once.
I would create a new view and view controller. You would not make a UIView be a UITableViewDelegate, you make a UIViewController be a UITableViewDelegate. But instead of doing that manually, instead make your new view controller a subclass of UITableViewController, if you're using iPhone OS 3.x+. You can then present this view controller modally.
You probably want to give the user a chance to cancel out of the selection. A good way to do that is to wrap your new dialog view controller in a UINavigationController and then put a "Cancel" button in the nav bar. Then use the delegate pattern to inform the parent view controller that the user has made their choice so you can pop the stack.
Here's what the code will look like inside your parent view controller, when you want to present this option dialog:
- (void)showOptionView
{
OptionViewController* optionViewController = [[OptionViewController alloc] initWithNibName:#"OptionView" bundle:nil];
optionViewController.delegate = self;
UINavigationController* navController = [[UINavigationController alloc] initWithRootViewController:optionViewController];
[self.navigationController presentModalViewController:navController animated:YES];
[navController release];
[optionViewController release];
}
Your OptionViewController .h will look like this:
#protocol OptionViewControllerDelegate;
#interface OptionViewController : UITableViewController
{
id<OptionViewControllerDelegate> delegate;
}
#property (nonatomic, assign) id<OptionViewControllerDelegate> delegate;
#end
#protocol OptionViewControllerDelegate <NSObject>
- (void)OptionViewController:(OptionViewController*)OptionViewController didFinishWithSelection:(NSString*)selection;
// or maybe
- (void)OptionViewController:(OptionViewController*)OptionViewController didFinishWithSelection:(NSUInteger)selection;
// etc.
#end
Your OptionViewController.m will have something like this:
- (void)madeSelection:(NSUInteger)selection
{
[delegate OptionViewController:self didFinishWithSelection:selection];
}
Which has a matching method back in your original view controller like:
- (void)OptionViewController:(OptionViewController*)OptionViewController didFinishWithSelection:(NSUInteger)selection
{
// Do something with selection here
[self.navigationController dismissModalViewControllerAnimated:YES];
}
There are plenty of examples throughout Apple's sample source code that follow this general pattern.