InputValidator.h

//
//  GPInputValidator.h
//  GrowingPains
//
//  Created by Kyle Clegg on 11/20/12.
//  Copyright (c) 2012 Kyle Clegg. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface InputValidator : NSObject

+ (BOOL) isValidName:(NSString *)name;
+ (BOOL) isValidEmail:(NSString* )emailAddress;
+ (BOOL) isValidPassword:(NSString *)password;
+ (BOOL) isValidPasswordLength:(NSString *)password;
+ (BOOL) isValidUsername:(NSString *)username;
+ (BOOL) isValidUsernameLength:(NSString *)username;

@end

InputValidator.m

//
//  GPInputValidator.m
//  GrowingPains
//
//  Created by Kyle Clegg on 11/20/12.
//  Copyright (c) 2012 Kyle Clegg. All rights reserved.
//

#import "InputValidator.h"

@implementation InputValidator

+ (BOOL) isValidName:(NSString *)name {
  
  return name.length > 0 ? YES : NO;
}

+ (BOOL) isValidEmail:(NSString *)emailAddress {
  
  // Email validation regex
	NSString *emailRegex =
    @"^[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$";
    NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];
    
    return [emailTest evaluateWithObject:emailAddress];
}

+ (BOOL) isValidPassword:(NSString *)password {
    NSPredicate *passwordTest = [NSPredicate predicateWithFormat:@"SELF MATCHES '.*( ).*'"];
    BOOL hasSpace = [passwordTest evaluateWithObject:password];
    return !hasSpace;
}

+ (BOOL) isValidPasswordLength:(NSString *)password {
    if ([password length] >= 6) {
		return YES;
	}
	return NO;
}

+ (BOOL) isValidUsername:(NSString *)username {
    NSString *usernameRegex =
    @"^[A-Za-z0-9\\-\\_]*";
    NSPredicate *usernameTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", usernameRegex];
    
    return [usernameTest evaluateWithObject:username];
}

+ (BOOL) isValidUsernameLength:(NSString *)username {
    if ([username length] >= 3) {
		return YES;
	}
	return NO;
}

@end