I asked this question earlier with way too much code.
The ViewController initializes a UIView chain, Controller>>View>>SubView, in the ViewController. After the SubView is initialized the ViewController is set as its delegate:
aSubView.delegate = self;
NSLog(#"$#",aSubview.delegate), returns the ViewController, so I know it is set.
In the SubView, NSLog(#"$#",self.delegate),returns random crap such a hr.lproj or a file path to the Foundation framework.
It crashes when attempting to implement any of the delegates methods, since the delegate doesn't link to the ViewController but instead randomness.
This is what the SubView.h file looks like:
#import "TestDelegate.h"
#interface TestSubView : UIView {
id<TestDelegate> delegate;
}
#property (assign) id<TestDelegate> delegate;
EDIT: ViewController is initialized in the app delegate as such:
ViewController *controller = [[ViewController alloc] init];
[window addSubview:controller.view];
[controller release];
The only other thing I added to the App Delegate, over the default is an import of the ViewController header
Is it possible the view controller object is being released/dealloced between the two calls to NSLog?
Related
I'm working on an app and I need to pass data between view controllers. I know this is a common question but I couldn't find an answer for my problem : I'm able to pass data from the FirstViewController (MasterViewController in my case) to the SecondViewController (SettingsViewController) but not the reverse. What happens is that I call a method from the FirstViewController in my SecondViewController.m file. This works and it logs the data. But when I quit the SecondViewController (using [[self presentingViewController] dismissViewControllerAnimated:YES completion:nil];) the data is reset.
I tried using other methods to pass data but it didn't work. I'm using this code to pass data:
MasterViewController *vc = [[MasterViewController alloc] initWithNibName:#"MasterViewController" bundle:nil];
[vc setPorts:SelectedPorts];
I also tried replacing [vc setPorts:SelectedPorts]; with vc.selectedCellIndexes = SelectedPorts; but the same problem occurs.
the setPorts method is declared in the FirstViewController.h file and SelectedPorts is a variable I declared in SecondViewController.m (it's not nil I checked).
Here's the setPorts: in FirstViewController.m :
- (void) setPorts:(id)selectedPorts {
selectedCellIndexes = selectedPorts;
NSLog(#"selectedCellIndexes : %#", selectedCellIndexes);
}
This logs the good value but when I log it in viewWillAppear in FirstViewController.m it's reset to the value it has before I called the method from SecondViewController.m.
Just to clarify, if I DON'T quit the SecondViewController.m, the data isn't reset.
I did read all your comments, and I really thanks you for your help. for convenience, I used a global variable.
Thanks for your help.
You have a list of ports in MasterViewController and you expect to use it in the SettingsViewController.
The MasterViewController can hold this list and SettingsViewController should have an access to it.
In SettingsViewController, have a setSelectedPort method:
#property (nonatomic, retain) id selectedPorts
- (void) setPorts:(id)selectedPorts;
The method saves the selected ports list into a property.
In MasterViewController, call the SettingsViewController and give it the list.
SettingsViewController *vc = [[SettingsViewController alloc] initWithNibName:#"SettingsViewController" bundle:nil];
[vc setSelectedPorts:yourValue];
When the list is modified inside the SettingsViewController, the list of ports contained in MasterViewController won't move even if you leave the SettingsViewController.
In secondViewController, You create protocol
#import <UIKit/UIKit.h>
#protocol sampleDelegate <NSObject>
- (void)passValue:(id)selectedPorts
#end
#interface SecondViewController : UIViewController
#property (nonatomic, strong) id <sampleDelegate> passDelegate;
#end
In viewDidLoad or wherever method as per your need, call method like this,
[self.passDelegate passValue:selectedPorts];
In FirstViewController.h,
Import the delegate <sampleDelegate>,
#import "SecondViewController.h"
#interface FirstViewController : UIViewController<SampleDelegate>
#end
In FirstViewController.m,
-(void)passValue:(id)selectedPorts
{
id receivedValues = selectedPorts;
}
and set self in your SecondViewController allocation,
SecondViewController *vc = [[SecondViewController alloc] initWithNibName:#"SecondViewController" bundle:nil];
vc.passDelegate = self;
There is nothing unusual in the getting result. By doing
MasterViewController *vc = [[MasterViewController alloc] initWithNibName:#"MasterViewController" bundle:nil];
[vc setPorts:SelectedPorts];
You are creating a new instance of MasterViewController from your SecondViewController. This is not the same from which you navigated to the SecondViewController. So you wont get the expected result. Since you are setting the ports([vc setPorts:SelectedPorts]) to the newly created instance of the Master.
Instead of creating a new instance,just hold the reference of the MasterViewController in SecondViewController in a property and assign it before moving to second VC. As a beginner I suggested this way. But using delegate is the prefferred way passing data back.
Either use delegate methods to communicate with the master VC from the modal VC, or you could do something like this if you want to retrieive some manipulated objects from the modal VC.
Set the object(s) as properties in the modal view controller's .h-file (so they are public).
Using unwind segues, in the master VC, just do this:
-(IBAction)exitModalVC:(UIStoryboardSegue*)segue
{
SomeObject *obj = ((YourModalVC*)segue.sourceViewController).someObject;
//Do what you want with obj
}
EDIT:
This will only work if you are using unwind segue (which is a neat way of dismissing modal VC when using story board)
And you are using this, which is not unwind segues:
[[self presentingViewController] dismissViewControllerAnimated:YES completion:nil];
You were creating a new instance of the first view controller from the 2nd view controller not accessing the same instance of the original caller. That was the reason why while you could see the logs but data were not there when you got back to the original caller - your MasterViewController.
You need to use delegate method. Check my answer for this SO.
This is problem related to object ownership.
Follow the below steps:
As per understanding you want reverse value from "SecondViewController" to "FirstViewController"
Don't create new object of FirstViewController in SecondViewController, it will not work.
Create object of "FirstViewController" in "SecondViewController.h" file.
#property (nonatomic,strong) FirstViewController *firstViewController;
When you navigate from FirstViewController to SecondViewController, please pass the "self".
e.g. SecondViewController *vc = [[SecondViewController alloc] initWithNibName:#"SecondViewController" bundle:nil];
vc.firstViewController = self;
If you want pass the reverse value to FirstViewController then in SecondViewController.m file.
[self.firstViewController setPorts:SelectedPorts];
And in FirstViewController.m refresh your controls with latest values.
Try above code will defiantly work as per your requirement.
How would I go about changing the a UILabel property in another view controller?
I have #import "SecondViewController.h" imported in the FirstViewController.m file and then
I have the following in a method in FirstViewController
-(IBAction) someAction {
SecondViewController *objV1 = [[SecondViewController alloc]init];
objV1.secondViewControllerLabel.alpha = 0.2;
NSLog(#"someAction");
}
when someAction is called nothing happens to the UILabel in the SecondViewController.
also, in this example both first and second view controllers are in another view controller called MainViewController. So, they are both onscreen at the same time.
thanks for any help.
From what you tell us, it would seem that you need to set the "embeded view controllers" as childs of the parent View Controller.
[mainViewController addChildViewController:childViewController];
[childViewController.view setFrame:self.view.bounds];
[self.childContainerView addSubview:childViewController.view];
[childViewController didMoveToParentViewController:self];
This is very powerful, because you can forward IBActions from the mainViewController to their child...
[mainViewController childViewControllers]
Returns an array of them, and also take a look at
– shouldAutomaticallyForwardRotationMethods
– shouldAutomaticallyForwardAppearanceMethods
So your child get automatically informed about the rotations of their parent.
To answer your question, you could do something like:
// In Parent View Controller
- (IBAction) anAction:(id) sender
{
for (CustomChildController *child in self.viewControllers) {
[child handleSomeAction];
}
}
Check out what the docs say for more details.
#Goles answer will work, but if you specifically want to trigger the change from FirstViewController.m you need to pass in a reference to SecondViewController somehow.
So you could do it with a custom init that takes a reference to your second viewcontroller as a parameter, or create a property on your FirstViewController that you can set from outside, which would be something like this:
FirstController.h:
#interface
..
#property (strong, nonatomic) UIViewController *second;
...
#end
FirstController.m:
#implementation
#synthesize second
In your parent ViewController you would create both the child view controllers, then:
ViewController1.second = ViewController2;
Then your action method would become:
-(IBAction) someAction {
self second.secondViewControllerLabel.alpha = 0.2;
NSLog(#"someAction");
}
Since in the secondViewController, secondViewControllerLabel has not been created yet, 'objV1.secondViewControllerLabel.alpha' will have no effect. Ideally, you should create a NSNumber property called labelAlpha in the secondViewController, set that property in the firstViewController, and then in the viewDidLoad of the second controller, add this line ::
self.secondViewControllerLabel.alpha = self.labelAlpha;
This will work for you.
I need to push a UIView into my UINavigation controller. I am doing it by
[self.view addSubview:showContactFlow];
And on a button click in UIView I need to push another UIViewController over the UIView. From the UIView I am not able to access self.navigationcontroller How can I do this?
Edit:
I have set the UIView as the view of a new UIViewController I am pushing into, the before mentioned UIViewController . Now I would like to know, how to handle the UIView button event inside its UIViewController, in which's view it is set.
Add a UINavigationController ivar to the UIView and assign it to the main view controller's. Then you should be able to access it from the UIView.
Edit:
Your UIView subclass:
// CustomView.h
#interface CustomView: UIView {
// ...
// your variables
// ...
UINavigationController *navController;
}
#property (nonatomic, assign) UINavigationController *navController; // assign, because this class is not the owner of the controller
// custom methods
#end
// CustomView.m
#implementation Customview
// synthesize other properties
#synthesize navController;
// implementation of custom methods
// don't release the navigation controller in the dealloc method, your class doesn't own it
#end
Then before the [self.view addSubview:showContactFlow]; line just add [showContactFlow setNavController:[self navigationController]]; and then you should be able to access your hierarchy's navigation controller from your UIView and use it to push other UIViewControllers.
You should try to work with an MVC approach. So your controller has access to all that stuff and can keep pushing and popping views, so the view doesn't need to know too much about the controller.
Otherwise, and for this case you can solve it fast by using delegation. So:
showContactFlow.delegate = self;
[self.view addSubview:showContactFlow];
So later in the UIView, you can just say:
[self.delegate addSubview:self];
This is gonna work, but it's not likely to be the best approach you should use.
On button click, you can present a view controller like,
-(void)buttonFunction{
ThirdVC *third= [[ThirdVC alloc]initWithNibNme];......
[self presentViewController:third animated:NO];
}
Using Core animation you can make NavigationController's pushviewController like animation on writing code in ThirdVC's viewWillAppear: method.
where do you add the UIButton is it in showContactFlow view or in the ViewController's view??
In regard to the modalViewControllers issue the correct method is
[self presentModalViewController:viewController animated:YES];
the standard animation in upwards
I have these two classes in my project:
#import <UIKit/UIKit.h>
#import "TableViewController.h"
#interface MainViewController : UIViewController
#end
and
#import <UIKit/UIKit.h>
#interface TableViewController : UITableViewController
#end
Within MainViewController.m, I am trying to do this:
TableViewController *tview = [[TableViewController alloc] initWithNibName:#"TableViewController"
bundle:nil];
tview.tableView.dataSource = tview;
tview.tableView.delegate = tview;
[self.view addSubview: tview.view];
However, this is crashing with an:
-[MainViewController tableView:numberOfRowsInSection:]: unrecognized selector sent to instance 0xb52dc90'
I don't understand why MainViewController is becoming the datasource/delegate for the TableViewController, when I already set the delegate/datasource in the init above. I also tried to set TableViewController's delegate/datasource to self from within its viewDidLoad, but the MainViewController still keeps acting as the delegate/datasource, regardless. I tried with the nib files hooked up and not hooked up, but no difference.
Ideally, I want the TableViewController to act as the delegate and datasource, and have its view added to MainViewController. How can I get this done?
Thank you!
Note: Neither solution worked for some reason. In the end, I recreated TableViewController as inheriting from UIViewController and set it as and things went normally then.
Where have you written the TableView delegate methods?? They should be inside your TableViewController Class and not inside the MainViewController Class.
Write the UITableView delegate methods inside the TableViewController Class.
Hope this will solve your problem...
Have you set delegate and datasource to nil in dealloc method?
tview.tableView.delegate = nil;
tview.tableView.dataSource = nil;
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