So I am fairly new to objective C and iOS programming. I am learning as I program and have a question. I am trying to modify a UITextField in my FirstViewController with my Second. How do I do this?
I have a UITextField name in FirstViewController and would like to be able to do something like firstViewController.name.text = #"new name"; inside of SecondViewController with a button and have the value changed so that if I switch tabs back to the FirstViewController I see the change has been made.
Thanks in advance for any help.
1、Set the FirstViewController as the delegate of SecondViewController；
2、Use NSNotificationCenter to notify the change event.
Well to call
firstViewController.name.text = #"new name"
You just need a reference to your first view controller inside of your second view controller. There are a number of ways to pass a reference around. Could go through the app delegate.
Another option that doesn't require you to have a reference to the first view controller inside the second view controller is to use NSNotificationCenter
Then you can have your second view controller observe a notification named say #"namechange" which contains the new name string.
When the button is pressed, you post a notification to the NSNotificationCenter with the new name attached. All the info is in the link above, or just google NSNotificationCenter for more tutorials and info.
Related
So I have this UINavigationController, I'm on the first moving to the next view, than I want to hit the 'back' button and to go back to the first view with the data that I saved into 'strAddress' on the second view. I want to present the data on the first view on 'lblShowStr.text'.
how can I manage to do that? I've searched all the web, found some people that wrote, but couldn't understand what they have been told there.
Thanks!
You can get a reference to the previous viewController in your navigation stack by saying:
NSArray *viewControllers = self.navigationController.viewControllers;
MyViewControllerClass *previousController = [viewControllers objectAtIndex:[viewControllers count] - 2];
You can then set a property on the 'previous' view controller to store your text, or even set the label outlet's text directly like this:
previousController.lblShowStr.text = self.strAddress;
It's not the best way to do it (the best way involves creating a custom delegate protocol or using NSNotificationCenter) but it's the easiest way.
In your first view controller you might have an NSString property called strAddress.
and you put that string into lblShowStr.text every time the view appears.
In your second view controller you might have a property pointing to an instance of view controller one. When you instantiate your second view controller you could assign the property on it to the first view controller.
secondViewController.firstViewController = self;
or
[secondViewController setFirstViewController:self];
Then when the user presses the back button viewDidAppear would get called for the first view and update the string.
I am assuming you don't want to store this data anywhere else e.g. in your model or nsuserdefaults etc.
Trying to send some data form my previous ViewController. To be more clear trying to send the selected date of the Si-Calendar to my secondView.
I'm adding the Calendar to my view in this way:
CalendarMonth *aCalendarView = [[CalendarMonth alloc] initWithFrame:CGRectMake(0, 0, 320, 324) logic:calendarLogic];
[aCalendarView selectButtonForDate:selectedDate];
[self.view addSubview:aCalendarView];
How do I use selected date and send it to my secondViewController (a UIView in which I'll display the selected date)?
Add a date property to your secondViewController, and set it appropriately when you create the instance...
It is a bit unclear what the first or second viewController is, but in general you could use a delegate for this purpose. For an example on how to do this, take a look at this answer
There are many ways to exchange data between view controllers, just take them as objects.
first controller hold a ref of the second controller, and transfer data using variables and methods
use delegate,
use notification
etc.
i can see that you are adding the CalenderMonth as the subview to another view. So if you dont release it (until u create the second view controller), you can set the selectedDate of the calender month obj to an iVar of second view controller. Else Create a delegate for CalenderMonth class. Set the second view controller as the delegate of the CalenderMonth and do the necessary.
I have two view controllers, one is MainViewController, the other is SetupViewController. I want a UILabel on MainViewController to set the text to the contents of a UITextField from the SetupViewController when a button is pressed in the SetupViewController.
In SetupViewController, I have this in the IBAction:
- (IBAction)donePressed:(id)sender {
MainViewController *mvc = [[MainViewController alloc] init];
[mvc.testLabelOnMVC setText:testTextFieldOnSVC.text];
[release mvc];
}
testLabelOnMVC (and testTextFieldOnSCV, with respective terms) is
#property (nonatomic, retain) UILabel *testLabelOnMVC;
and is also synthesized.
Every time I try, it doesn't work. Nothing happens, nothing changes. I have no errors or warnings. Can anyone help me out?
The view of your MainViewController does not exist until you reference the MainViewController's view property (which forces viewDidLoad to execute). You must reference the view (or otherwise force the view to be constructed) before you attempt to modify any UI objects in the MainViewController.
You are allocating a new MainViewController when you press the button, then you are setting the text of the label on this new controller, not on the MainViewController that your app is showing.
To fix this, create either and IBOutlet or iVar that points to the original MainViewController and set the text on that instead.
Easiest way is to create a #property in the main view controller and write the text in there. Then just read it in the second MVC's viewDidLoad.
The only views that MainViewController should worry about are the ones that it owns; it shouldn't be trying to access the view hierarchy managed by SetupViewController. Likewise, SetupViewController should not directly modify views in MainViewController's view graph.
The right way to do what you're asking is for the two controllers to talk to each other, either directly or via the data model. For example, let's say that your MainViewController instantiates SetupViewController. If that's the case, it'd be natural for mvc to set itself as svc's delegate, so that svc sends it a messages like -setupController:didUpdateTestStringTo:. MainViewController's implementation of that method could then save the new test string somewhere and update it's testLabel field.
Another example: MainViewController instantiates SetupViewController. SetupViewController contains a field where the user can enter a new value for the test string. Before exiting, SetupViewController writes the contents of that field into NSUserDefaults or some other common data storage. When control returns to MainViewController, that object reads the shared data and updates itself as necessary, including setting the new value for testLabel.
There are other variations on the same theme, but the common thread here is that neither view controller has to directly access views that it doesn't own.
You can change the text of the label if the view is already loaded. Instead of initializing the viewcontroller, retrieve it from the view stack if you are using navigation controller.
I dont know if your viewController is already loaded or not.
I created a new Navigation Based Application project.Then in MainWindow.xib I added a button to the navigationbar. I would like to push a new View onto the screen where I can enter information, which will be added as an object to the array of the UITableView.
But I don't know where to write the IBAction to link the button to (Appdelegate or the RootViewController)? Because as you see in the screenshot, it resides in MainWindow.xib because the RootViewController is merely a Table and doesn't contain the navigation. But in the document view of MainWindow.xib it is located under the RootViewController.
Do I have to create a new View Controller inside the XIB as well and create an IBOutlet for it?
I tried putting the code inside my AppDelegate and reference the button to the delegate but it doesn't work.
Please help. Thanks in advance.
See the screenshot here: http://i56.tinypic.com/5djbcm.png
When you ask yourself a question "where does this action belong" it's most probably a controller because controllers handle event flows in your app. Next question - "What controller is in charge when this action happens? What controller is most interested in this action?". Answer in your case is root table controller (RootViewController instance). Create an IBAction method in it which will push form controller (one you use to enter information) to navigation controller.
// somewhere in RootViewController.m
- (IBAction)addNewEntry {
NewEntryFormController *c = [[[NewEntryFormController alloc] init] autorelease];
// ...
[self.navigationController pushViewController:c animated:YES];
}
I hope that you will succeed in at least a little to clarify me how and what to do, I'm sure I'm wrong, so I really need an expert opinion.
I have two viewcontroller together with nibs what I want is to call function that is in first class from another ViewController, the problem is that another viewcontroller manages to call this function but the only thing I can see that is done is NSlog which outputs in the console (which I put in that position to know that the function is called)
example:
FirstViewController.m
-(void)drawingFunction:(NSString*)inputText{
NSLog("Feature was launched");
/* showing stuff in FirstView.xib */
}
SecondViewController.m
-(void)turnOnFunction:(id)sender{
FirstViewController *stuff= [[PrviViewController alloc] init];
[stuff drawingFunction:#"ShowAll"];
}
Basically when I call that function in the PrviViewController.m meaning without reference to the outside e.g.
[self drawingFunction:#"ShowAll"];
everything is well displayed, but when I try to call this function from SecondViewController.m all I see is just a "feature was launched" on the console
I really don't know what to do ...
if i get you right, the FirstViewController is on top of the view controller hierarchy (either within a navigation controller or presented modal)? So, if that is the case just creating an instance of SecondViewController and calling a function which should change the user interface on the view which corresponds to SecondViewController will do nothing at all.
You have to present the SecondViewController and its view with presentModalViewController:animated: for instance. After that the view of SecondViewController will be shown and you can do any changes on that view. Also calling the method drawingFunction: will act as you expect it.
Cheers,
Andreas
You're confusing instances with classes. You don't send messages (call functions) to classes, you send them to instances.
In this case, you have two entirely separate instances of FirstViewController. The first is created by loading the nib and the second is created in -[SecondController turnOnFunction:]. The drawingFunction: message is being sent to the second instance when you want it to be sent to the first.
You need to link the nib instance of FirstViewController to the SecondController instance. You can do that with an outlet in interface builder or you can assign it when you create the display the SecondController.