UIButton in a UITabBarController crashing when clicked! - uitabbarcontroller

Question

I tried to include a custom button programmatically inside a UIView which is a subview of UITabBarController.
The button is displays fine but when I click it, it crashes without an error message. Its strange that sometimes it does inconsistently:
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSCFString playButton]: unrecognized selector sent to instance 0x632cd10'
I even tried removing any code in my play button method, i tried changing the name playButton to playAction, I also tried add the button directly to "self" not to aboutView but the result is still the same.
My guess is it got something to do with the tabBar having a UIView as a subview with a button on it. I don't know.
Here's a code snippet of how i built the tabBar in my appDelegate method
// About Tab
aboutViewC = [[[AboutViewController alloc] init] autorelease];
aboutNavC = [[[UIViewController alloc] init] autorelease];
aboutNavC.title = #"About";
aboutNavC.view = aboutViewC.view;
// Lessons Tab
lessonsViewC = [[[LevelViewController alloc] init] autorelease];
lessonsViewC.title = #"Levels";
lessonsNavC = [[[UINavigationController alloc] initWithRootViewController:lessonsViewC] autorelease];
lessonsNavC.title = #"Lessons";
lessonsNavC.viewControllers = [NSArray arrayWithObjects:lessonsViewC, nil];
tabBarController = [[UITabBarController alloc] init];
tabBarController.viewControllers = [NSArray arrayWithObjects:aboutNavC, lessonsNavC, nil];
and heres the code for implementing the AboutViewController class
AboutViewController.h
#import
#interface AboutViewController : UIViewController {
UIButton *playSoundButton;
UIView *aboutView;
}
- (void)playButton;
#end
AboutViewController.m
#import "AboutViewController.h"
#implementation AboutViewController
- (void)dealloc {
[playSoundButton release];
[aboutView release];
[super dealloc];
}
- (void)viewDidLoad {
aboutView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 480)];
[playSoundButton = [UIButton buttonWithType:UIButtonTypeCustom] retain];
image = [UIImage imageNamed:#"bt_play.png"];
[playSoundButton setImage:image forState:UIControlStateNormal];
[playSoundButton addTarget:self action:#selector(playButton) forControlEvents:UIControlEventTouchUpInside];
playSoundButton.frame = CGRectMake(0, 350, 40, 40);
[aboutView addSubview:playSoundButton];
stopSoundButton.hidden = YES;
playSoundButton.hidden = NO;
[self.view addSubview:aboutView];
[super viewDidLoad];
}
- (void)playButton
{
NSLog(#"playAction method");
}
#end
Thanks in advance!

Answer 1

[playSoundButton = [UIButton buttonWithType:UIButtonTypeCustom] retain]; should read playSoundButton = [[UIButton buttonWithType:UIButtonTypeCustom] retain];
(i.e. move the first [ further right to UIButton)

Answer 2

Thanks tob for the feedback, i actually know how to implement retain statement, it was a typo i didn't notice. surprisingly, that is not the problem and the code run's fine now leaving the typo unchanged.
The real problem was in my appDelegate method.
Instead of
// About Tab
aboutViewC = [[[AboutViewController alloc] init] autorelease];
aboutNavC = [[[UIViewController alloc] init] autorelease];
aboutNavC.title = #"About";
aboutNavC.view = aboutViewC.view;
// Lessons Tab
lessonsViewC = [[[LevelViewController alloc] init] autorelease];
lessonsViewC.title = #"Levels";
lessonsNavC = [[[UINavigationController alloc] initWithRootViewController:lessonsViewC] autorelease];
lessonsNavC.title = #"Lessons";
lessonsNavC.viewControllers = [NSArray arrayWithObjects:lessonsViewC, nil];
tabBarController = [[UITabBarController alloc] init];
tabBarController.viewControllers = [NSArray arrayWithObjects:aboutNavC, lessonsNavC, nil];
should be
// About Tab
aboutViewC = [[[AboutViewController alloc] init] autorelease];
aboutViewC.title = #"About";
// Lessons Tab
lessonsViewC = [[[LevelViewController alloc] init] autorelease];
lessonsViewC.title = #"Levels";
lessonsNavC = [[[UINavigationController alloc] initWithRootViewController:lessonsViewC] autorelease];
lessonsNavC.title = #"Lessons";
lessonsNavC.viewControllers = [NSArray arrayWithObjects:lessonsViewC, nil];
tabBarController = [[UITabBarController alloc] init];
tabBarController.viewControllers = [NSArray arrayWithObjects:aboutViewC, lessonsNavC, nil];