PseudoDateFormatter, custom UITextField input month/year expiration

PseudoDateFormatter

#import "ViewController.h"

@interface ViewController () <UITextFieldDelegate>
@property (strong, nonatomic) UITextField *textField;

@end

@implementation ViewController
- (void)viewDidLoad
{
    [super viewDidLoad];
    CGFloat desiredFieldWidth = 100.0f;
    _textField = [[UITextField alloc] initWithFrame:CGRectMake((self.view.bounds.size.width - desiredFieldWidth)/2, 110, desiredFieldWidth, 44)];
    _textField.text = @"XX/YYYY";
    _textField.delegate = self;
    [self.view addSubview:_textField];
}

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    NSArray* arrayString = [NSArray arrayWithArray:[self translateStringToArray:self.textField.text]];
    NSLog(@"arrastring count = %i", arrayString.count);
    NSLog(@"array string = %@", arrayString);
    
    if (arrayString.count > 6) {
        [[[UIAlertView alloc] initWithTitle:nil message:@"invalid input" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil] show];
        _textField.text = @"XX/YYYY";
        return NO;
    }
    
    if (arrayString.count == 0) {
        _textField.text = @"XX/YYYY";
    }
    
    if (arrayString.count == 1) {
        _textField.text = [NSString stringWithFormat:@"%@X/YYYY", arrayString[0]];
    }
    
    if (arrayString.count == 2) {
        _textField.text = [NSString stringWithFormat:@"%@%@/YYYY", arrayString[0], arrayString[1]];
    }
    
    if (arrayString.count == 3) {
        _textField.text = [NSString stringWithFormat:@"%@%@/%@YYY", arrayString[0], arrayString[1], arrayString[2]];
    }
    
    if (arrayString.count == 4) {
        _textField.text = [NSString stringWithFormat:@"%@%@/%@%@YY", arrayString[0], arrayString[1], arrayString[2], arrayString[3]];
    }
    
    if (arrayString.count == 5) {
        _textField.text = [NSString stringWithFormat:@"%@%@/%@%@%@Y", arrayString[0], arrayString[1], arrayString[2], arrayString[3], arrayString[4]];
    }
    
    if (arrayString.count == 6) {
        _textField.text = [NSString stringWithFormat:@"%@%@/%@%@%@%@", arrayString[0], arrayString[1], arrayString[2], arrayString[3], arrayString[4], arrayString[5]];
    }

    return YES;
}

-(NSArray *)translateStringToArray:(NSString *)input
{
    NSMutableArray *arr = [NSMutableArray array];
    for (int i=0; i < input.length; i++) {
        NSString *string = [input substringWithRange:NSMakeRange(i, 1)];
        if ([[NSScanner scannerWithString:string] scanInt:nil]) {
            NSLog(@"is integer");
            [arr addObject:string];
        } else {
            NSLog(@"is not integer");
        }
    }
    
    return arr;
}

@end