iOS Segmentation Fault Errors while programming in Objective C

PolygonShape.h:
//
//  PolygonShape.h
//  Assignment2A Stanford
//
//  Created by Adheer Chauhan on 10/21/09.
//  Copyright 2009 Drexel University. All rights reserved.
//

#import <Cocoa/Cocoa.h>


@interface PolygonShape : NSObject //These are for all the instance variables of the class
{
	int numberOfSides;
	int minimumNumberOfSides;
	int maximumNumberOfSides;
}

@property (readwrite) int numberOfSides;//if we didn't specify anything, it would still be readwrite as that is the default
@property (readwrite) int minimumNumberOfSides;
@property (readwrite) int maximumNumberOfSides;
@property (readonly) float angleInDegrees;
@property (readonly) float angleInRadians;
@property (readonly) NSString *name;
@property (readonly) NSString *description;

-(id)initWithNumberOfSides:(int)sides minimumNumberOfSides:(int)min maximumNumberOfSides:(int)max;


@end


PolygonShape.m
//
//  PolygonShape.m
//  Assignment2A Stanford
//
//  Created by Adheer Chauhan on 10/21/09.
//  Copyright 2009 Drexel University. All rights reserved.
//

#import "PolygonShape.h"


@implementation PolygonShape

#define MINSIDES 3
#define MAXSIDES 12
#define DEFAULTSIDES 5

@synthesize numberOfSides;
@synthesize minimumNumberOfSides;
@synthesize maximumNumberOfSides;

-(id)initWithNumberOfSides:(int)sides minimumNumberOfSides:(int)min maximumNumberOfSides:(int)max
{
	if (self = [super init]) {//This initializes the instance variables to their default values
		minimumNumberOfSides = MINSIDES;
		maximumNumberOfSides = MAXSIDES;
		numberOfSides = DEFAULTSIDES;
		
		[self setNumberOfSides:sides];//This initializes the instance variables using the setter methods
		[self setMinimumNumberOfSides:min];
		[self setMaximumNumberOfSides:max];
	}
	
	return self;
}

//Custom setter method for maximumNumberOfSides
-(void)setMaximumNumberOfSides:(int)max
{
	if((max <= 12) && (max >= minimumNumberOfSides))
		maximumNumberOfSides = max;
	else
		NSLog(@"Invalid Maximum Number of Sides %i, must be Greater than or equal to %i and less than or equal to 12", max, minimumNumberOfSides);
}

//Custom setter method for minimumNumberOfSides
-(void)setMinimumNumberOfSides:(int)min
{
	if((min > 2) && (min <= maximumNumberOfSides))
		minimumNumberOfSides = min;
	else
		NSLog(@"Invalid Minimum Number of Sides %i, must be Greater than 2 and less than or equal to %i", min, maximumNumberOfSides);
}

//Custom setter method for numberOfSides
-(void)setNumberOfSides:(int)num
{
	if((num <= maximumNumberOfSides) && (num >= minimumNumberOfSides))
		numberOfSides = num;
	else
		NSLog(@"Invalid number of sides %i, must be between %i and %i.", num, minimumNumberOfSides, maximumNumberOfSides);
}



-(id)init
{
	return [self initWithNumberOfSides:DEFAULTSIDES minimumNumberOfSides:MINSIDES maximumNumberOfSides:MAXSIDES];
}

-(float)angleInDegrees
{
	return 180 * (numberOfSides - 2)/numberOfSides;
}

-(float)angleInRadians
{
	return (2 * M_PI) * (numberOfSides - 2)/numberOfSides;
}

-(NSString *)name
{
	NSString *nameOfPolygon;
	switch (numberOfSides)
	{
		case 3:
			nameOfPolygon = @"Triangle";
			break;
		case 4:
			nameOfPolygon = @"Square";
			break;
		case 5:
			nameOfPolygon = @"Pentagon";
			break;
		case 6:
			nameOfPolygon = @"Hexagon";
			break;
		case 7:
			nameOfPolygon = @"Heptagon";
			break;
		case 8:
			nameOfPolygon = @"Octagon";
			break;
		case 9:
			nameOfPolygon = @"Enneagon";
			break;
		case 10:
			nameOfPolygon = @"Decagon";
			break;
		case 11:
			nameOfPolygon = @"Hendecagon";
			break;
		case 12:
			nameOfPolygon = @"Dodecagon";
			break;
		default:
			nameOfPolygon = @"Undefined";
			break;
	}
	return nameOfPolygon;
}

-(NSString *)description
{
	return [NSString stringWithFormat:@"Hello, I am a %d-sided polygon (aka a %@) with angles of %@ degrees (%@ radians)", numberOfSides, [self name], [self angleInDegrees], [self angleInRadians]];
}

-(void)dealloc
{
	NSLog(@"dealloc is being called");
	[super dealloc];
}

@end


Assignment2A Stanford.m:
#import <Foundation/Foundation.h>
#import "PolygonShape.h"

void PrintPathInfo()
{
	NSString *path = @"~";
	NSString *stringtext = [path stringByExpandingTildeInPath];//path is an instance of class NSString and it is calling method stringByExpandingTildeInPath
	//NSLog(@"My home folder is at '%@'", stringtext);
	NSArray *pathcomponents = [stringtext pathComponents];//we use the instance stringtext of type NSString containing the pathComponents method
	for (NSString *item in pathcomponents)//we go through each element of pathcomponents array and print it using NSLog 
	{
		NSLog([item description]);
	}
}

void PrintProcessInfo()
{
	NSString *procName = [[NSProcessInfo processInfo] processName];
	int procid = [[NSProcessInfo processInfo] processIdentifier];
	NSLog(@"Process name: '%@' Process ID: '%d'", procName, procid);
	//NSLog(text);
}

void PrintBookmarkInfo()
{
	//NSArray *keys = [NSArray arrayWithObjects:@"Stanford University", @"Apple", @"CS193P", @"Stanford on iTunesU", "Stanford Mall", nil];
	NSURL *url1 = [NSURL URLWithString:@"http://www.stanford.edu"];
	NSURL *url2 = [NSURL URLWithString:@"http://www.apple.edu"];
	NSURL *url3 = [NSURL URLWithString:@"http://cs193p.stanford.edu"];
	NSURL *url4 = [NSURL URLWithString:@"http://itunes.stanford.edu"];
	NSURL *url5 = [NSURL URLWithString:@"http://www.stanfordshop.edu"];
	//NSArray *values [NSArray arrayWithObjects:url1, url2, url3, url4, url5, nil];
	NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];//The dictionary at the RHS of the '=' sign is a method that initializes a dictionary
	[dictionary setObject:url1 forKey:@"Stanford University"];
	[dictionary setObject:url2 forKey:@"Apple"];
	[dictionary setObject:url3 forKey:@"CS193P"];
	[dictionary setObject:url4 forKey:@"Stanford on iTunes U"];
	[dictionary setObject:url5 forKey:@"Stanford Mall"];
	
	//NSMutableDictionary *dictionary = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"http://www.stanford.edu", @"Stanford University", @"http://www.apple.com", @"Apple", @"http://cs193p.stanford.edu", @"CS193P", @"http://itunes.stanford.edu", @"Stanford on iTunes U", @"http://stanfordshop.com", @"Stanford Mall", nil];
	for (id key in dictionary) 
	{
		if([key hasPrefix:@"Stanford"])
		{
			NSLog(@"Key: %@, Value: %@", key, [dictionary objectForKey:key]);
		}
	}
}

void PrintIntrospectionInfo()
{
	NSMutableArray *array = [NSMutableArray array];
	NSString *string = @"This is for Stanford University's iPhone Application Development course";
	NSURL *url = [NSURL URLWithString:@"http://www.qualcomm.com"];
	NSProcessInfo *procinfo = [NSProcessInfo processInfo];
	NSArray *keys = [NSArray arrayWithObjects:@"key1", @"key2", @"key3", @"key4",nil];
	NSArray *values = [NSArray arrayWithObjects:@"value 1", @"value 2", @"value 3", @"value 4",nil];
	NSMutableDictionary *dictionary = [NSMutableDictionary dictionaryWithObjects:values forKeys:keys];
	NSMutableString *mutablestring = [NSMutableString string];
	mutablestring = @"Programming the iPhone Rocks!!!";
	
	[array addObject:string];
	[array addObject:url];
	[array addObject:procinfo];
	[array addObject:dictionary];
	[array addObject:mutablestring];
	
	for (NSString *element in array)
	{
		NSLog(@"The name of this class is %@", [element className]);
		if([element	isMemberOfClass:[NSString class]])
			NSLog(@"Is Member of NSString: YES");
		else
			NSLog(@"Is Member of NSString: NO");
		
		if([element isKindOfClass:[NSString class]])
			NSLog(@"Is Kind of NSString: YES");
		else
			NSLog(@"Is Kind of NSString: NO");
		
		SEL sel = @selector(lowercaseString);
		if([element respondsToSelector:sel])
		{
			NSLog(@"Responds to lowercaseSring: YES");
			NSLog(@"Lower case string of this element is: %@",[element lowercaseString]);
		}
		else
			NSLog(@"Responds to lowercaseString: NO");
		
		if([[element className] hasSuffix:@"Dictionary"])
		{
			for(id key in dictionary)
			{
				NSLog(@"Key: %@, Value: %@",key, [dictionary objectForKey:key]);
			}
		}
		NSLog(@"=========================================");
		
	}
}

void PrintPolygonInfo()
{
	NSMutableArray *pArray = [NSMutableArray array];
	PolygonShape *pgon = [[PolygonShape alloc] initWithNumberOfSides:4 minimumNumberOfSides:3 maximumNumberOfSides:7];
	NSLog(@"Adding this polygon to the array: %@", pgon);
	[pArray addObject:pgon];
	[pgon release];
	
	pgon = [[PolygonShape alloc] initWithNumberOfSides:6 minimumNumberOfSides:5 maximumNumberOfSides:9];
	NSLog(@"Adding this polygon to the array: %@", pgon);
	[pArray addObject:pgon];
	[pgon release];
	
	pgon = [[PolygonShape alloc] initWithNumberOfSides:12 minimumNumberOfSides:9 maximumNumberOfSides:12];
	NSLog(@"Adding this polygon to the array: %@", pgon);
	[pArray addObject:pgon];
	[pgon release];
	
	for(PolygonShape *p in pArray)
	{
		p.numberOfSides = 10;
	}
	
	[pArray release];
}

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
	
    // insert code here...
	NSLog(@"Result for Section 1\n");
	PrintPathInfo(); //Section 1
	NSLog(@"Result for Section 2\n");
	PrintProcessInfo();//Section 2
	NSLog(@"Result for Section 3\n");
	PrintBookmarkInfo();//Section 3
	NSLog(@"Result for Section 4\n");
	PrintIntrospectionInfo();//Section 4
	NSLog(@"Result for Assignment 2A");
	PrintPolygonInfo();
    // NSLog(@"Hello, World!");
    [pool drain];
    return 0;
}


Assignment2A Stanford_Prefix.pch
//
// Prefix header for all source files of the 'Assignment2A Stanford' target in the 'Assignment2A Stanford' project.
//

#ifdef __OBJC__
    #import <Foundation/Foundation.h>
#endif