I am trying to create a Master-Detail application with a UITableView controller as both the master and detail. What I need to do is pass 8 strings of data when a row is selected to the detail UITableViewController. What's the best way of accomplishing this? I plan to have the detail UITableViewController as static cells, not dynamic.
You can create a variable in the master view controller to access the detail view controller. Then, in the master view controller's viewDidLoad, you can set up this variable so from this point on, all calls to self.detailViewController in the master view controller will be sent to the detail view controller. Sample code:
In MasterViewController.h:
#class DetailViewController // do not use include here to avoid reference cycles, just identify DetailViewController as a class
#interface MasterViewController : UITableViewController
// in the interface, declare property to access detail view controller
#property (strong, nonatomic) DetailViewController *detailViewController;
#end
In MasterViewController.m:
#include "DetailViewController.h"
// in the implementation, synthesize
#interface DetailViewController : UITableViewController
#synthesize DetailViewController;
// when the view loads
- (void)viewDidLoad {
// call super method
[super viewDidLoad];
// if you used XCode's built-in Matser/Detail application, this will set detailViewController to the detail view controller
self.detailViewController = (ITLDetailViewController *)[[self.splitViewController.viewControllers lastObject] topViewController];
}
This way, when you're in the master view controller code, you can call self.detailViewController.someProperty or [self.detailViewController someMethod].
Related
I am passing textfield data between two view controllers. i have two view controllers Firstviewcontroller, Secondviewcontroller. i have embed them in navigation but when i click the button on first view controller, second view controller is not showing only black screen is showing.below is my code.
First view controller.h
#import <UIKit/UIKit.h>
#import "secondViewController.h"
#interface FirstViewController : UIViewController<SecondViewControllerDelegate>
#property(nonatomic) secondViewController *secondview;
- (IBAction)btnclick:(id)sender;
#property (strong, nonatomic) IBOutlet UITextField *textfield1;
#end
First view controller.m
- (IBAction)btnclick:(id)sender {
secondViewController *SecondViewController= [[secondViewController alloc]init];
SecondViewController.data=self.textfield1.text;
[self.navigationController pushViewController:SecondViewController animated:YES];
}
- (void)dataFromController:(NSString *)data
{
[self.textfield1 setText:[NSString stringWithFormat:#"%#",data]];
}
Seconviewcontroller.h
#protocol SecondViewControllerDelegate <NSObject>
#required
- (void)dataFromController:(NSString *)data;
#end
#interface secondViewController : UIViewController
#property (nonatomic, retain) NSString *data;
#property(nonatomic,weak)id<SecondViewControllerDelegate> _delegate;
#property (strong, nonatomic) IBOutlet UITextField *textfield2;
#end
Seconviewcontroller.m
- (void)viewDidLoad {
[super viewDidLoad];
self.textfield2.text=[NSString stringWithFormat:#"%#",_data];
// Do any additional setup after loading the view.
}
whats the reason ??
You have to either use storyboard and let it intanciate the view controller for you:
[self.storyboard instantiateViewControllerWithIdentifier:#"SecondViewController"]
Or you can use xib files and tell the view controller which one to load:
[[SecondViewController alloc] initWithNibName:#"SecondViewController" bundle:nil]
second view controller is not showing only black screen is showing
Typically, this means that the view controller has no view. Your code does not explain where secondViewController is expected to get its view from. Is there a secondViewController.xib? If there is, is it correctly configured with a view outlet? If not, what does this view controller do in order to get its view?
Note that you have done a very odd thing with capitalization: you have given your class a small letter (secondViewController), while your instance has a capital latter (SecondViewController). This is backwards and a big mistake, and you should correct it immediately. Perhaps the problem is just a capitalization problem; if you call your class secondViewController and your xib file SecondViewController, that is not a match and they won't find each other.
I see "IBOutlet" in your code, it means you created the user interface of secondviewcontroller on storyboard. I guess [[secondViewController alloc]init] does not get UI element from storyboard then the black screen is shown. You have to create instance of secondViewController by loading from storyboard file.
Basically:
you can get storyboard via storyboard file name
on storyboard, Secondviewcontroller has an storyboard id which is set in Identity Inspector and you can use it to get instance of Secondviewcontroller
You can refer this link for more detail
loading iOS viewcontroller from storyboard
Hope this can help!
How can I pass data between a Navigation Controller and a Table View Controller? I have tried prepareForSegue method but it doesn't work.. I have tried to put a breakpoint to see if the flow calls this method but it seems that the prepareForSegue of my Navigation Controller class is never called. Here is some sample of code :
NavController.h :
#interface NavController : UINavigationController
#end
NavController.m :
- (void) prepareForSegue: (UIStoryboardSegue *) segue sender: (id) sender
{
TableViewController *destViewController = (TableViewController*)segue.destinationViewController;
destViewController.title = #"Home";
destViewController.URLValue = #"http://www.example.com";
}
TableViewController.h :
#interface TableViewController : UITableViewController
#property (nonatomic, strong) NSString *URLValue;
#end
It sounds like the navigation controller is your root view controller (ie, if you select the navigation controller scene and inspect its details in Xcode, the "Initial Scene" checkbox should be checked). Because it's the initial scene and is arrived in only one way, try setting default values in viewDidLoad: on your TableViewController.
I'm trying to make a MVC and I have a CustomViewController and a CustomView. I have all the properties set up so that when a CustomViewController is created the view attached to the controller automatically becomes a instance of CutsomView.
My question is, how do I set it up so that I have one CustomViewController and, lets say, 1 or 2 CustomViews that are assigned to the controller?
MainViewController adds the CustomViewController as a child view controller which then adds the view associated with CustomViewController. Now after this is done, is there a way to add a second CustomView with it being attached to the CustomViewController?
Inside my MainViewController:
Is this possible or do I just need to create a new CustomViewController for every CustomView I want?
The purpose of this is to have these views stacked on top of each other with different data without calling a segue. Kinda like the way the new Facebook Paper app stacks their views.
Make CustomView class as a Parent of CustomViewController :
e.g:-
- ParentViewController.h
#interface ParentViewController : UIViewController
// You can put all common method here
- (IBAction) SetNavigationTitle:(NSString *)title;
#end
- LoginViewController
#interface LoginViewController : ParentViewController // in place of NSObject
#end
#implementation LoginViewController
- (void)viewDidLoad
{
[self SetNavigationTitle:#"User"];
}
#end
I have 2 table view controllers where I on button click on first controller, I am pushing to another view controller.
On the second table view controller, I have a list of items which is checkmarked upon selection. I want to return the selected value to the first view controller.
Also, please let me know how can I use that value in first view controller.
I cant use seagues and the second view controller is generic so I cannot set any of the variables of first view controller in it.
One option would be to create a delegate for that second view controller
In the .h you could declare
#protocol SecondControllerDelegate <NSObject>
- (void)selectionDidFinish:(NSArray*)objects;
#end
#interface SecondViewController : UIViewController
#property(nonatomic, weak) id<SecondControllerDelegate> delegate;
Then in your .m in view will disappear :
- (void)viewWillDisappear:(BOOL)animated{
[self.delegate selectionDidFinish:yourArray];
}
And in your first view controller you'd have to implement this protocol :
in .h :
#interface FirstViewController : UIViewController <SecondControllerDelegate>
and in .m
- (void)selectionDidFinish:(NSArray*)objects{
//Do whatever you want with selected objects
}
and of course when you create your second view controller you'd have to do :
SecondViewController *sVC = [[SecondViewController alloc] init];
sVC.delegate = self;
[self.navigationController pushViewController:sVC animated:YES];
A possible solution is to create a mutable object (NSMutableArray, NSMutableDictionary) in the parent controller and pass it to the child, so the child can modify it and when you are back to the parent - the mutable object will contain the modified values.
Another approach, which requires a little more knowledge is to use a protocol. The basic idea is to create a protocol and a delegate, so the child can "notify" the parent that it chose some values. You can check these examples:
http://www.theappcodeblog.com/2011/04/15/passing-data-between-views-tutorial-using-a-protocol-delegate-in-your-iphone-app/
http://iosdevelopertips.com/objective-c/the-basics-of-protocols-and-delegates.html
Please tell me if you need more information.
You can create delegates. Checkout the following link:
http://www.hardcodedstudios.com/home/ryan-newsome/simpledelegatetutorialforiosdevelopment
I'm currently trying to have a better understanding on how the mechanisms of passing data between controllers work and I'm a little confused especially when passing data back from a second view controller to the main view controller.
This is what I have that works but don't fully understand. I have two view controllers, in the first one I have a button that when clicked it basically goes to the second view controller and a label which shows a message sent from the second view controller. In the second view controller I have a button and a textField, the button basically sends whatever is in the textfield to the label in main view controller.
Here is the code...
// FirstVC.h
#import <UIKit/UIKit.h>
#import "SecondVC.h"
#interface FirstVC : UIViewController <passNames>
#property (nonatomic, strong) NSString* firstNameString;
#property (weak, nonatomic) IBOutlet UILabel *firstNameLabel;
#end
//FirstVC.m
#import "FirstVC.h"
#implementation FirstVC
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([[segue identifier]isEqualToString:#"secondController"])
{
UINavigationController *navController = segue.destinationViewController;
SecondVC *vc2 = (SecondVC*)navController.topViewController;
[vc2 setDelegate:self];
}
}
-(void)viewWillAppear:(BOOL)animated
{
self.firstNameLabel.text = _firstNameString;
}
-(void)setFirstName:(NSString *)firstName
{
_firstNameString = firstName;
}
#end
//SecondVC.h
#import <UIKit/UIKit.h>
#protocol passNames <NSObject>
-(void)setFirstName:(NSString*)firstName;
#end
#interface SecondVC : UIViewController
#property (retain)id <passNames> delegate;
- (IBAction)send:(UIBarButtonItem *)sender;
#property (nonatomic, strong) NSString *firstNameString;
#property (weak, nonatomic) IBOutlet UITextField *firstNameText;
#end
//SecondVC.m
#import "SecondVC.h"
#import "FirstVC.h"
#interface SecondVC ()
#end
#implementation SecondVC
- (IBAction)send:(UIBarButtonItem *)sender
{
_firstNameString = _firstNameText.text;
[[self delegate]setFirstName:_firstNameString];
[self dismissViewControllerAnimated:YES completion:nil];
}
#end
Can someone explain how the prepareForSegue method works in the above code? The reason for this question is because I added an NSLog and it looks like this method is only called in the transition from main view controller to the second controller. Why is this method needed if it is not called when transitioning from second view controller to main view controller which in my case is what I'm doing? It makes sense to use it when passing data from main view controller to a second controller not on the case shown above.
Can some explain the whole mechanism when passing data back to the main view controller?
FYI, I do understand about protocols and delegation.
Thanks a lot.
In your case, you are setting your delegate method of the second view controller to self in mainViewController in you prepareForSegue. This means that apart from navigating to the SecondViewController, you are implementing the callback mechanism in your main view controller, so that your delegate method gets called when the value is passed from the second view controller and this delegate method collects the value as a parameter to handle it in the main View Controller. You might have set the delegate of VC2 as self inn your prepareForSegue because you are creating the instance of VC2 in this method to navigate to the second controller.
Your goal is to hand back the data, like this:
[[self delegate] setFirstName:_firstNameString];
But you can't do that unless you know who to send setFirstName: to, and the compiler won't let you do it unless you guarantee that whoever you are sending setFirstName: to can accept that message.
That is what prepareForSegue prepares. FirstVC has declared that it adopts the passNames protocol, which means that it implements setFirstName:. And now you are saying:
[vc2 setDelegate:self];
...where self is the FirstVC instance. This solves both problems at once. The SecondVC instance (vc2) now has a delegate (the FirstVC instance), it is the right object to send the info back to, and because its delegate is declared as adopting passNames, we know that SecondVC can actually send setFirstName: to that delegate.
Now to the heart of your actual question: The reason for doing this in prepareForSegue is merely that this is the only moment when the FirstVC instance and the SecondVC instance "meet" one another! There is no other moment when the FirstVC instance has a reference to the SecondVC instance so as to be able to call setDelegate on it in the first place. If you weren't using segues and storyboards, the FirstVC would simply create the SecondVC instance directly - and would set itself as its delegate, just as you do:
SecondVC *vc2 = [SecondVC new];
UINavigationController *nav = [
[UINavigationController alloc] initWithRootViewController: vc2];
[vc2 setDelegate:self];
[self presentViewController: nav animated: YES completion: nil];
This is one reason I don't like storyboards: they muddy the story. It's all so simple and obvious when you don't use them and just do everything directly like this.