Auto-formatting phone number UITextField on the iPhone

In this post, we'll use our PhoneNumberFormatter to implement an auto-formatting phone number text field in an attempt to mimic the behavior of iPhone's native apps, like Phone and Contacts.

So, let's call the text field in question myTextField. We start by calling addTarget on the text field to make it call the autoFormatTextField method in our view controller whenever it gets updated, either by the user or some other piece of code. If your view is ready, you should declare the handler as an IBAction and bind through IB. The method would then update the contents of the text fields to the formatted string returned by the formatter. If we do it that way, we'll also need to use a semaphore to prevent the method from being called endlessly.

The implementation outline would be:

// declarations

UITextField *myTextField;

int myTextFieldSemaphore;

PhoneNumberFormatter *myPhoneNumberFormatter;

NSString *myLocale; //@"us"



// init semaphore

myTextFieldSemaphore = 0;



// bind events programatically, skip when using IB.

[myTextField addTarget:self

                action:@selector(autoFormatTextField:)

      forControlEvents:UIControlEventValueChanged

];



// handle events

- (void)autoFormatTextField:(id)sender {

 if(myTextFieldSemaphore) return;

 myTextFieldSemaphore = 1;

 myTextField.text = [phoneNumberFormatter format:myTextField.text withLocale:myLocale];

 myTextFieldSemaphore = 0;

}

Update: As pointed out in the comments, for newer SDKs you may need to bind to UIControlEventEditingChanged. Thanks for your feedback!

//bind events

[myTextField addTarget:self

                action:@selector(autoFormatTextField:)

      forControlEvents:UIControlEventEditingChanged

];

Locale-aware phone number formatting on the iPhone

iPhone developers often find themselves trying to stick to the standards set by Apple. Most of the time, doing so is facilitated by the SDK and the results are better. Sometimes though, it's not easy at all, mainly because some APIs are not open.

One example is phone number formatting. The Contacts application utilizes an auto-formatting UITextField for phone number entry. Many business applications would make use of such functionality but it's not provided by the current SDK.

I've been through that and was not happy about the task. After procrastinating for a while, I thought of a solution and later on, I actually implemented it, and it worked well for me. I wished I could make it into the sought after NSPhoneNumberFormatter, but I was done with the task. I thought I should share it with fellow iPhone developers. I hope many will be able to use it right away as-is, and it would be great if someone could finish the job and make the formatter.

I acquired the predefined localized phone formats from the UIPhoneFormats.plist. I was mainly interested in the us locale, but I kept the implementation generic. The main idea is to build some sort of a finite state machine (FSM) for the phone format and use it to process the input string. The FSM will both validate and add formatting characters to the string as needed. If the whole input could be processed successfully, then it is a valid format and the output is returned.

The problem that I didn't solve yet, is when the string can be matched to more than one format. I had to manually sort the formats from the most restrictive to the least restrictive, so the one that comes first is always selected. This hack was okay for US formats, but there was nothing I could do with the last 3 UK formats since, to me, they are essentially the same. I guess this can be worked around somehow.

I'll post the code here, and will try to add more comments later. Please feel free to add your comments or ask for clarifications.

Update 02/14/2010: I'm so glad to have habermann24 join in and create his phoney ruby lib. If your Ruby/Rails application deals with phone numbers, you got to check it out!

Update 09/08/2010: Check out libphonenumber: Google's common Java, C++ and Javascript library for parsing, formatting, storing and validating international phone numbers. The Java version is optimized for running on smartphones. You'll need to look for the AsYouTypeFormatter.java. Update++, check out the comment below by +SpoofApp.

Update 08/15/2011: Updates on libphonenumber: New development of the library will be presented in the 35th Internationalization and Unicode Conference in a session titled: libphonenumber - The Swiss Army Knife of International Telephone Number Handling. See session description for details.

Update 02/06/2015: libphonenumber on Github by Google Internationalization (i18n).

PhoneNumberFormatter.h

//  Created by Ahmed Abdelkader on 1/22/10.

//  This work is licensed under a Creative Commons Attribution 3.0 License.



#import <Foundation/Foundation.h>



@interface PhoneNumberFormatter : NSObject {

 //stores predefiend formats for each locale

 NSDictionary *predefinedFormats;

}



/*

 Loads predefined formats for each locale.



 The formats should be sorted so as more restrictive formats should come first.



 This is necessary as the formatting code processes the formats in order and

 selects the first one that matches the whole input string.

*/

- (id)init;



/*

 Attemps to format the phone number to the specified locale.

*/

- (NSString *)format:(NSString *)phoneNumber withLocale:(NSString *)locale;



/*

 Strips the input string from characters added by the formatter.

 Namely, it removes any character that couldn't have been entered by the user.

*/

- (NSString *)strip:(NSString *)phoneNumber;



/*

 Returns true if the character comes from a phone pad.

*/

- (BOOL)canBeInputByPhonePad:(char)c;



@end

PhoneNumberFormatter.m

//  Created by Ahmed Abdelkader on 1/22/10.

//  This work is licensed under a Creative Commons Attribution 3.0 License.



#import "PhoneNumberFormatter.h"



@implementation PhoneNumberFormatter



- (id)init {

 NSArray *usPhoneFormats = [NSArray arrayWithObjects:

         @"+1 (###) ###-####",

         @"1 (###) ###-####",

         @"011 $",

         @"###-####",

         @"(###) ###-####", nil];



 NSArray *ukPhoneFormats = [NSArray arrayWithObjects:

         @"+44 ##########",

         @"00 $",

         @"0### - ### ####",

         @"0## - #### ####",

         @"0#### - ######", nil];



 NSArray *jpPhoneFormats = [NSArray arrayWithObjects:

         @"+81 ############",

         @"001 $",

         @"(0#) #######",

         @"(0#) #### ####", nil];



 predefinedFormats = [[NSDictionary alloc] initWithObjectsAndKeys:

      usPhoneFormats, @"us",

      ukPhoneFormats, @"uk",

      jpPhoneFormats, @"jp",

      nil];

 return self;

}



- (NSString *)format:(NSString *)phoneNumber withLocale:(NSString *)locale {

 NSArray *localeFormats = [predefinedFormats objectForKey:locale];

 if(localeFormats == nil) return phoneNumber;

 NSString *input = [self strip:phoneNumber];

 for(NSString *phoneFormat in localeFormats) {

  int i = 0;

  NSMutableString *temp = [[[NSMutableString alloc] init] autorelease];

  for(int p = 0; temp != nil && i < [input length] && p < [phoneFormat length]; p++) {

   char c = [phoneFormat characterAtIndex:p];

   BOOL required = [self canBeInputByPhonePad:c];

   char next = [input characterAtIndex:i];

   switch(c) {

    case '$':

     p--;

     [temp appendFormat:@"%c", next]; i++;

     break;

    case '#':

     if(next < '0' || next > '9') {

      temp = nil;

      break;

     }

     [temp appendFormat:@"%c", next]; i++;

     break;

    default:

     if(required) {

      if(next != c) {

       temp = nil;

       break;

      }

      [temp appendFormat:@"%c", next]; i++;

     } else {

      [temp appendFormat:@"%c", c];

      if(next == c) i++;

     }

     break;

    }

   }

   if(i == [input length]) {

    return temp;

   }

  }

  return input;

}



- (NSString *)strip:(NSString *)phoneNumber {

 NSMutableString *res = [[[NSMutableString alloc] init] autorelease];

 for(int i = 0; i < [phoneNumber length]; i++) {

  char next = [phoneNumber characterAtIndex:i];

  if([self canBeInputByPhonePad:next])

   [res appendFormat:@"%c", next];

 }

 return res;

}



- (BOOL)canBeInputByPhonePad:(char)c {

 if(c == '+' || c == '*' || c == '#') return YES;

 if(c >= '0' && c <= '9') return YES;

 return NO;

}



- (void)dealloc {

 [predefinedFormats release];

 [super dealloc];

}



@end

Parsing a simple XML node on iPhone

I wanted to parse some simple XML response from a server and I really wouldn't bother to use NSXMLParser or libxml2 as discussed here on stackoverflow. I get a single node and I just wanted to get the content. I ended up with this utility method:

+ (NSString *)xmlNodeContent:(NSData *)xmlData {
 NSString *node = [[NSString alloc] initWithData:xmlData encoding:NSUTF8StringEncoding];
 NSString *content = @"";
 if([node length] > 0) {
  int start = [node rangeOfString:@">"].location + 1;
  int end = [node rangeOfString:@"<" options:NSBackwardsSearch].location;
  content = [node substringWithRange:NSMakeRange(start, end - start)];
 }
 [node release];
 return content;
}

Multi-line UITableViewCell using UILabel

No need for UITextViews or custom UITableViewCells. You can use standard UITableViewCellStyles and make the detailTextLabel accept multiple lines and specify its line break mode. The code would be:

static NSString *CellIdentifier = @"MyCell"; 
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
 cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue2
     reuseIdentifier:CellIdentifier] autorelease];
}
cell.textLabel.text = @"Label';
cell.detailTextLabel.text = @"Multi-Line\nText";
cell.detailTextLabel.numberOfLines = 2;
cell.detailTextLabel.lineBreakMode = UILineBreakModeWordWrap;

You will also need to return a suitable height for the multi-line cell. A height of (44.0 + (numberOfLines - 1) * 19.0) should work fine.

Update: As Vaibhav mentions in the comments, you can use variants of sizeWithFont from the NSString UIKit Additions to get the required height. I guess sizeWithFont:forWidth:lineBreakMode is the one to use here. Thanks for your input!

Moving UITextFields over the keyboard without a UIScrollView

I had a UIViewController with a couple of UITextFields attached to its default UIView and everything was fine. Later on, I added a couple more text fields, so I had to make sure all text fields are displayed properly when the keyboard shows up. I thought about using a UIScrollView or maybe a UITableView which scrolls naturally, but I thought I didn't have to change my controller just for that. I found these 2 posts [1, 2] on stackoverflow pretty useful, but I still had to tweak the code a little and here's what I got:

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [activeField resignFirstResponder];
}

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField {
    activeField = textField;
    [self setViewMovedUp:YES];
    return YES;
}

- (BOOL)textFieldShouldReturn:(UITextField *)textField {
    [activeField resignFirstResponder];
    [self setViewMovedUp:NO];
    activeField = nil;
    return YES;
}

- (void)setViewMovedUp:(BOOL)movedUp {
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.5];
 
    CGRect viewFrame = self.view.frame;
    CGRect textFieldFrame = [activeField convertRect:[activeField bounds] toView:self.view];
 
    if (movedUp) {
        viewFrame.origin.y = -textFieldFrame.origin.y/1.8;
    } else {
        viewFrame.origin.y = 0;
    }
    self.view.frame = viewFrame;
 
    [UIView commitAnimations];
}

Let me explain a couple of things here, first: activeField is a UIControl* instance variable I added to my UIVeiwController. second: you can replace (textFieldFrame.origin.y/1.8) with any function of (textFieldFrame.origin.y) that would do the job. Maybe you can try assigning certain offsets for each range of y values, but I preferred this neat form and the result was neat too.