Switching view controllers crashes with an uncaught exception

Question

I'm trying to switch views between view controllers in my iPhone app, but it crashed. Basically I'm switching from mainScreen to test.

I get an error in the debugger:

0x01d6a000  <+0000>  push   %ebp
0x01d6a001  <+0001>  mov    %esp,%ebp
0x01d6a003  <+0003>  int3   
0x01d6a004  <+0004>  leave  (HIGHLIGHTED)
0x01d6a005  <+0005>  ret    
0x01d6a006  <+0006>  nopw   %cs:0x0(%eax,%eax,1)

mainscreen.h

#import <UIKit/UIKit.h>

@interface MainScreen : UIViewController {

}

-(IBAction)btnFirstPage:(id)sender;

@end

mainscreen.m

#import "MainScreen.h"
#import "test.h"

@implementation MainScreen

-(IBAction)btnFirstPage:(id)sender{

 test1 = [[test1 alloc] 

    initWithNibName:@"test"  (test may not respond to -alloc)

    bundle:nil];

    [self.view addSubview:test1.view];

/* etc. */

test.h

#import <UIKit/UIKit.h>

@interface test : UIViewController {
}

@end

Answer 1

This looks odd: test1 = [[test1 alloc] ...]. You are sending the alloc message to a variable, which I assume is initially the null pointer, and is thus being quietly ignored. You should invoke alloc on test1's class type, not test1 itself.

Answer 2

test1 = [[test alloc] initWithNibName:@"test" undle:nil]; //here it must be test. not test1

When you create objects from classes you have to use alloc and allocWithZone static methods use in the NSObject class. So you have to use Class name. Not the variable name.(test1)