iPhone/Objective-c - Gaining access to a previous ViewController from a subview? - iphone

Question

How do I access a previous view controller while in a subview? Because I'm able to perform actions but I'm just not able to use self.[my main view controller].
This is my code, for testing purposes:
PhotoViewController.m
-(IBAction)likeButton:(UIButton *)sender
{
//this part works
NSString *num = #"2";
self.label.text = [NSString stringWithFormat:#"%# + %#",
self.label.text,
num];
//this part doesn't work
//switch over to the third view to see if it worked
self.tabBarController.selectedIndex = 0;
}
I have a UITabBarController and one of its view controllers has a UIScrollView. Inside of the UIScrollView is a PhotoViewController object.
AppDelegate.m
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch
MyTabBarViewController *vc2 = [[MyTabBarViewController alloc] init];
SecondViewController *vc3 = [[SecondViewController alloc] init];
controller = [[DemoAppViewController alloc] init];
controller.view.frame = CGRectMake(0, 20, 320, 460);
controller.title = #"Intro Screen";
vc2.title = #"Explore";
vc3.title = #"Send a Pic";
UITabBarController *tbc = [[UITabBarController alloc] init];
tbc.viewControllers = [NSArray arrayWithObjects:controller, vc2, vc3, nil];
[controller release];
[vc2 release];
[vc3 release];
[self.window addSubview:tbc.view];
[self.window makeKeyAndVisible];
return YES;
}
Also, my TabBarViewController.m //not my actual UITabBarController though, wording is confusing
- (void) viewWillAppear:(BOOL)animated
{
[super viewWillAppear:YES];
arrayCount = [array count];
scroller.delegate=self;
scroller.pagingEnabled=YES;
scroller.directionalLockEnabled=YES;
scroller.showsHorizontalScrollIndicator=NO;
scroller.showsVerticalScrollIndicator=NO;
//should have an array of photo objects and the number of objects, correct?
scrollWidth = 0;
scroller.contentSize=CGSizeMake(arrayCount*scroller.frame.size.width, scroller.frame.size.height);
for (int i = 0; i < arrayCount;i++) {
PhotoViewController *pvc = [[PhotoViewController alloc] initWithNibName:#"PhotoViewController" bundle:nil];
UIImageView *scrollImageView = [[UIImageView alloc] initWithFrame:CGRectOffset(scroller.bounds, scrollWidth, 0)];
CGRect rect = scrollImageView.frame;
pvc.view.frame = rect;
pvc.label.textColor = [UIColor whiteColor];
id individualPhoto = [array objectAtIndex:i];
NSLog(#"%#",individualPhoto);
NSArray *keys=[individualPhoto allKeys];
NSLog(#"%#",keys);
NSString *imageURL=[individualPhoto objectForKey:#"source"];
NSURL *url = [NSURL URLWithString:imageURL];
NSData *data = [NSData dataWithContentsOfURL:url];
pvc.imageView.image = [[UIImage alloc] initWithData:data];
pvc.label.text = [individualPhoto objectForKey:#"id"];
[scroller addSubview:pvc.view];
[scrollImageView release];
//[pvc release];
scrollWidth += scroller.frame.size.width;
}
if (arrayCount > 3) {
pageControl.numberOfPages=3;
} else {
pageControl.numberOfPages=arrayCount;
}
pageControl.currentPage=0;
}

Answer 1

If a UIView subclass needs to message a controller above itself, a common (and often recommended?) way to do this is to have the view subclass implement the delegate protocol (a weak linked instance variable pointing to the view controller that you want to use). The view controller should then set itself as the delegate of the view when that view is being initialize.

Answer 2

Try defining this method in your PhotoViewController:
+ (YOURTABBARCONTROLLER*)parentTabBarController:(UIResponder*)view {
id nextResponder = nil;
id v = view;
while (nextResponder = [v nextResponder]) {
NSLog(#"Found Responder: %#", nextResponder); //-- ADDED THIS
if ([nextResponder isKindOfClass:[YOURTABBARCONTROLLER class]])
return nextResponder;
v = nextResponder;
}
return nil;
}
it will traverse the responder chain and return the first controller of a given type that is found. Replace YOURTABBARCONTROLLER with your actual tab bar controller class and you should be able to have:
-(IBAction)likeButton:(UIButton *)sender
{
//this part works
NSString *num = #"2";
self.label.text = [NSString stringWithFormat:#"%# + %#",
self.label.text,
num];
[PhotoViewController parentTabBarController:self.view].selectedIndex = 0;
// self.tabBarController.selectedIndex = 0;
}
Updated
-(IBAction)likeCommentButton:(UIButton *)sender
{
//code goes here
TypeSomethingViewController *typeSomethingViewController = [[TypeSomethingViewController alloc] init];
typeSomethingViewController.delegate = self;
[self presentModalViewController:typeSomethingViewController animated:YES];
[typeSomethingViewController release];
}
-(void)typeSomethingViewController:(TypeSomethingViewController *)controller didTypeSomething:(NSString *)text
{
//NSLog(#"response: %#", controller);
NSString *commentID = self.label.text;
for(UIViewController *controller in [PhotoViewController parentTabBarController:self.parentViewController.view].viewControllers)
{
if([controller isKindOfClass:[DemoAppViewController class]])
{
DemoAppViewController *davc = (DemoAppViewController *)controller;
//[davc commentPicture:commentID :message];
[davc likePicture:commentID];
}
}
[PhotoViewController parentTabBarController:self.view].selectedIndex = 0;
[self dismissModalViewControllerAnimated:YES];
}

Answer 3

Try this out to switch to the first controller.
self.tabBarController.selectedViewController
= [self.tabBarController.viewControllers objectAtIndex:0];
Change the index value to switch to whichever controller you want to switch to.

Answer 4

The tabBarController should be a property of the app delegate.
Try accessing it with :
MyAppDelegate *appDelegate = (MyAppDelegate *)[[UIApplication sharedApplication]
delegate];
appDelegate.tabBarController.selectedIndex = 0;
Unless you declare the same property in PhotoViewController, you won't be able to access it this way.
Try importing the app delegate header in PhotoViewController.h like so :
#import "MyAppDelegate"
then try this code above replacing tabBarController by tbc which, as the example suggests is the name given to this property.