UITextField cursor positioning

NFViewController.m

//
//  NFViewController.m
//  TextFieldTest
//
//  Created by Florian Sey on 06/02/14.
//  Copyright (c) 2014 NeoFacto. All rights reserved.
//

#import "NFViewController.h"

@interface NFViewController ()
<UITextFieldDelegate>

@property (weak, nonatomic) IBOutlet UITextField *textField;

@property (nonatomic, assign) NSUInteger position;

@end

@implementation NFViewController

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    self.textField.text = @"abcdefghijklmnopqrstuvwxyz";
    [[NSNotificationCenter defaultCenter]
     addObserver:self
     selector:@selector(textFieldDidChange:)
     name:UITextFieldTextDidChangeNotification
     object:nil];
}

- (void)textFieldDidChange:(NSNotification *)note
{
    UITextField *textField = note.object;
    [NFViewController selectTextForInput:textField atRange:NSMakeRange(self.position, 0)];
}

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if ([string isEqualToString:@""])
    {
        self.position = range.location;
    }
    else
    {
        if (range.length <= string.length)
        {
            self.position = range.location + string.length;
        }
        else
        {
            self.position = range.location - string.length + range.length;
        }
    }
    return YES;
}

+ (void)selectTextForInput:(UITextField *)input atRange:(NSRange)range {
    UITextPosition *start = [input positionFromPosition:[input beginningOfDocument]
                                                 offset:range.location];
    UITextPosition *end = [input positionFromPosition:start
                                               offset:range.length];
    [input setSelectedTextRange:[input textRangeFromPosition:start toPosition:end]];
}

@end