Emulate PIN unlock screen

gistfile1.m

@property (strong, nonatomic) IBOutlet UITextField *pin1_1;
@property (strong, nonatomic) IBOutlet UITextField *pin1_2;
@property (strong, nonatomic) IBOutlet UITextField *pin1_3;
@property (strong, nonatomic) IBOutlet UITextField *pin1_4;
@property (nonatomic, strong) NSString *pinText;


- (void)viewDidLoad
{
	(...)
    [self.pin1_1 setDelegate:self];
    [self.pin1_2 setDelegate:self];
    [self.pin1_3 setDelegate:self];
    [self.pin1_4 setDelegate:self];
}
    

-(UITextField *)nextPinFieldTo:(UITextField *)textField
{
    if(textField == self.pin1_1)
    {
        return self.pin1_2;
    }
    else if(textField == self.pin1_2)
    {
        return self.pin1_3;
    }
    else if(textField == self.pin1_3)
    {
        return self.pin1_4;
    }
    else
    {
        return nil;
    }

    
}

-(BOOL)textFieldShouldReturn:(UITextField *)textField
{
    [textField resignFirstResponder];
    return YES;
}

-(BOOL)textFieldShouldEndEditing:(UITextField *)textField
{
    return YES;
}


-(void)textFieldDidEndEditing:(UITextField *)textField
{
    textField.text = self.pinText;
        
    if (textField == self.pin1_4)
    {
        [self login];
    }
    else
    {
        [[self nextPinFieldTo:textField] becomeFirstResponder];        
    }
    
}


-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)newString
{
	self.pinText = newString;
    [textField resignFirstResponder];
    return NO;

}