How to pass self to another class in iOS - ios

Question

I have to create a button multiple times on different ViewControllers and add the event to it. What i have done i created a class to handle them. I pass my UINavigationController to it and add a button to it. but nothing happens. i mean the button doesn't display. i call my Util class like
MyUtil *util = [[MyUtil alloc];
[util initWithNavAndAddBackButton:self.NavigationController];
// now it should display my custom back button which i have created but it is not displayed.
// i have passed nav by value and add a button to it but don't know why it is not showing it.
MyUtil.h
-(void)initWithNavAndAddBackButton:(UINavigationController *)nav;
MyUtil.m
-(void)initWithNavAndAddBackButton:(UINavigationController *)nav
{
UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
[btn setImage:[UIImage imageNamed:#"icon_back.png"] forState:UIControlStateNormal];
// [btn setTarget:self action:#selector(popView:) forControlEventTouchUPInside];
// how can i pass self(Context in Android) that for which activity it is calling for
[button setFrame:CGRectMake(0,0,36,20);
UIBarButtonItem *barbtn = [[UIBarButton alloc] initWithCustomView:btn];
nav.navigationController.navigationItem.leftBarButtonItem = barbtn;
}
-(void) popView:(UINavigationController *)nav
{
[nav popViewControllerAnimated:YES];
}
Problems i have
First i have pass UINaviagation and add the UIBarbutton to it but it is not displaying .When I write the same code in each ViewController class . it is running accurately. I simply want to do this in a seperate class like a handler.
And i also want to push and pop in that activity. How can i pass self that or i mean how does this class knows the target that for which class this action belongs to. How can i pass the event for the ViewContoller.

Answer 1

Try returning your navigation controller instance to ViewController from MyUtil.
MyUtil.h
-(UIBarButtonItem *)initWithNavAndAddBackButton();
MyUtil.m
-(UIBarButtonItem *)initWithNavAndAddBackButton()
{
UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
[btn setImage:[UIImage imageNamed:#"icon_back.png"] forState:UIControlStateNormal];
[button setFrame:CGRectMake(0,0,36,20);
UIBarButtonItem *barbtn = [[UIBarButton alloc] initWithCustomView:btn];
return barbtn;
}
ViewController.m
MyUtil *util = [[MyUtil alloc];
self.navigationItem.rightBarButtonItem = [util initWithNavAndAddBackButton:self.NavigationController];
Because when you pass an object, it is not passed by reference.

Answer 2

MyUtil.m
+ (void)setNavigationItem:(UINavigationItem *)navItem forViewController:(UIViewController *)controller
{
UIImage *image = [UIImage imageNamed:#"icon_back.png"];
UIBarButtonItem *item = [[UIBarButtonItem alloc] initWithImage:image
style:UIBarButtonItemStylePlain
target:controller
action:#selector(popView)];
navItem.leftBarButtonItem = item;
}
ViewController.m
[MyUtil setNavigationItem:self.navigationItem forViewController:self];
- (void)popView
{
[self.navigationController popViewControllerAnimated:YES];
}

Answer 3

MyUtil *util = [[MyUtil alloc];
[util initWithNavAndAddBackButton:self.NavigationController];
Should be
MyUtil *util = [[MyUtil alloc] init];
[util initWithNavAndAddBackButton:self.NavigationController];
You are used with Android. In iOS is diffrent.
self.navigationController takes care of pushing and pop viewcontrollers
If you want a custom button to be used everywhere you can use the delegate method
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
// Make sure your segue name in storyboard is the same as this line
if ([[segue identifier] isEqualToString:#"YOUR_SEGUE_NAME_HERE"])
{
// Get reference to the destination view controller
YourViewController *vc = [segue destinationViewController];
// Pass any objects to the view controller here, like...
[vc setMyButtonHere:button];
}
}