界面如下图

当我点击第二个标签 single的时候，界面就直接跳出来了，直接调到模拟器的主界面了，怎么回事？

那个标签页的.h代码：如下

#import <UIKit/UIKit.h>


@interface SingleComponentPickerViewController : UIViewController
<UIPickerViewDelegate,UIPickerViewDataSource>
{
	IBOutlet UIPickerView  *singlepicker;
	NSArray *pickerdate;


}
@property (nonatomic,retain) UIPickerView *singlepicker;
@property (nonatomic,retain) NSArray *pickerdate;

-(IBAction)buttonpressed;

@end

标签页 .m 代码

#import "SingleComponentPickerViewController.h"


@implementation SingleComponentPickerViewController
@synthesize singlepicker;
@synthesize  pickerdate;

// The designated initializer.  Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad.
/*
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization.
    }
    return self;
}
*/

/*
// Implement loadView to create a view hierarchy programmatically, without using a nib.
- (void)loadView {
}
*/

-(IBAction)buttonpressed
{
	NSInteger row=[singlepicker selectedRowInComponent:0];//select the frist singlepicker
	NSString *select=[pickerdate objectAtIndex:row];
	NSString *title=[[NSString alloc]initWithFormat:@"you select %@",select];
	UIAlertView *alert=[[UIAlertView alloc]initWithTitle:title
												message:@"thanks you for choosing"
												delegate:nil
									   cancelButtonTitle:@"you are welcome" 
									   otherButtonTitles:nil];
	[alert show];
	[alert release];
	[title release];
}

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
	NSArray *array=[[NSArray alloc] initWithObjects:@"Luke",@"Leia",@"Han",@"Chewbacca",@"Artoo",@"Threepio",@"Lando",nil];
	self.pickerdate=array;
	[array release];
    [super viewDidLoad];
}


/*
// Override to allow orientations other than the default portrait orientation.
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    // Return YES for supported orientations.
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
*/

- (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.
}

- (void)viewDidUnload {

    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}


- (void)dealloc {
	[singlepicker release];
	[pickerdate release];
    [super dealloc];
}

#pragma mark -
#pragma mark Picker Data Source Methods
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
	return 1;
}

-(NSInteger)pickerView:(UIPickerView*)pickerView numberOfRowInComponent:(NSInteger)component
{
	return [pickerdate count];
}
#pragma mark Picker delegate Methods
-(NSString*) pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
	return [pickerdate objectAtIndex:row];
}

@end