EXEC_BAD_ACCESS in iOS5 for IBAction - iphone

Question

I have written a sample code for button click action in xcode 4.2 for iOS5.
Here is the code
.h
#import <UIKit/UIKit.h>
#interface FirstViewController : UIViewController
#property(strong,nonatomic) IBOutlet UIButton *button;
-(IBAction)changed;
#end
.m
#import "FirstViewController.h"
#implementation FirstViewController
#synthesize button=_button;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self)
{
// Custom initialization
}
return self;
}
- (void)didReceiveMemoryWarning
{
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
#pragma mark - View lifecycle
- (void)viewDidLoad
{
[_button addTarget:self action:#selector(changed) forControlEvents:UIControlEventTouchUpInside];
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
}
-(IBAction)changed
{
NSLog(#"clicked");
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return YES;
}
#end
But when I click the button. I am getting exception. how to solve this issue? the same is working in iOS 4.3

Answer 1

first change this code into this one
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
[_button addTarget:self action:#selector(changed) forControlEvents:UIControlEventTouchUpInside];
}

Answer 2

I have found solution for my problem.
The main problem is that, if I create a view controller object locally (i.e., inside any method) and add it as subview then, when you invoke any IBAction, at that time it will raise an exception because, the memory for that viewController is getting deallocated automatically when declared locally.

Answer 3

I guess he needs to add data member for that button as well. I mean code should look like this.
#interface FirstViewController : UIViewController{
IBOutlet *UIButton *button;
}
#property(strong,nonatomic) IBOutlet UIButton *button;
-(IBAction)changed;
#end
and try replacing
#synthesize button = _button;
with
#synthesize button;
in your .m file.

Answer 4

You have the wrong message signature for your changed action. It should be:
- (IBAction)changed:(id)sender
and in the addTarget line of code:
#selector(changed:)
PS: Why are you using _button? I don't think this is related to the problem, but you should be using self.button instead. Accessing instance variables directly should be avoided, especially in this case, where you are allowing the compiler to decide what name the variable should have.
PPS: As mentioned by #InderKumarRathore, you should also be calling [super viewDidLoad] before running your own code.