Further refine the registration and verification views.

// FREEBIE

Signal/src/view controllers/CodeVerificationViewController.m

@@ -139,6 +139,7 @@ NSString *const kCompletedRegistrationSegue = @"CompletedRegistration";
                                                         @"Text field placeholder for SMS verification code during registration");
     _challengeTextField.font = [UIFont ows_lightFontWithSize:21.f];
     _challengeTextField.textAlignment = NSTextAlignmentCenter;
+    _challengeTextField.keyboardType = UIKeyboardTypePhonePad;
     _challengeTextField.delegate    = self;
     [self.view addSubview:_challengeTextField];
     [_challengeTextField autoPinWidthToSuperviewWithMargin:kHMargin];
@@ -392,18 +393,6 @@ NSString *const kCompletedRegistrationSegue = @"CompletedRegistration";
     [self.view endEditing:NO];
 }
 
-- (NSString *)stringByFilteringString:(NSString *)input
-                     withCharacterSet:(NSCharacterSet *)characterSet {
-    NSMutableString *result = [NSMutableString new];
-    for (NSUInteger i=0; i < input.length; i++) {
-        unichar c = [input characterAtIndex:i];
-        if ([characterSet characterIsMember:c]) {
-            [result appendFormat:@"%c", c];
-        }
-    }
-    return [result copy];
-}
-
 - (BOOL)textField:(UITextField *)textField
     shouldChangeCharactersInRange:(NSRange)range
                 replacementString:(NSString *)insertionText {
@@ -423,18 +412,14 @@ NSString *const kCompletedRegistrationSegue = @"CompletedRegistration";
     // * Take partial input if possible.
     
     NSString *oldText = textField.text;
-    NSCharacterSet *validCharacterSet = [NSCharacterSet decimalDigitCharacterSet];
     // Construct the new contents of the text field by:
     // 1. Determining the "left" substring: the contents of the old text _before_ the deletion range.
     //    Filtering will remove non-decimal digit characters like hyphen "-".
-    NSString *left = [self stringByFilteringString:[oldText substringToIndex:range.location]
+    NSString *left = [oldText substringToIndex:range.location].digitsOnly;
-                                  withCharacterSet:validCharacterSet];
     // 2. Determining the "right" substring: the contents of the old text _after_ the deletion range.
-    NSString *right = [self stringByFilteringString:[oldText substringFromIndex:range.location + range.length]
+    NSString *right = [oldText substringFromIndex:range.location + range.length].digitsOnly;
-                                   withCharacterSet:validCharacterSet];
     // 3. Determining the "center" substring: the contents of the new insertion text.
-    NSString *center = [self stringByFilteringString:insertionText
+    NSString *center = insertionText.digitsOnly;
-                                    withCharacterSet:validCharacterSet];
     // 3a. Trim the tail of the "center" substring to ensure that we don't end up
     //     with more than 6 decimal digits.
     while (center.length > 0 &&
@@ -474,9 +459,17 @@ NSString *const kCompletedRegistrationSegue = @"CompletedRegistration";
 }
 
 - (void)setVerificationCodeAndTryToVerify:(NSString *)verificationCode {
-    NSCharacterSet *validCharacterSet = [NSCharacterSet decimalDigitCharacterSet];
+    NSString *rawNewText = verificationCode.digitsOnly;
-    self.challengeTextField.text = [self stringByFilteringString:verificationCode
+    NSString *formattedNewText = (rawNewText.length <= 3
-                                                withCharacterSet:validCharacterSet];
+                                  ? rawNewText
+                                  : [[[rawNewText substringToIndex:3]
+                                      stringByAppendingString:@"-"]
+                                     stringByAppendingString:[rawNewText substringFromIndex:3]]);
+    self.challengeTextField.text = formattedNewText;
+    // Move the cursor after the newly inserted text.
+    UITextPosition *newPosition = [self.challengeTextField endOfDocument];
+    self.challengeTextField.selectedTextRange = [self.challengeTextField textRangeFromPosition:newPosition
+                                                                                    toPosition:newPosition];
     [self verifyChallengeAction:nil];
 }
 

Signal/src/view controllers/RegistrationViewController.m

@@ -26,6 +26,7 @@ static NSString *const kCodeSentSegue = @"codeSent";
 
     // Do any additional setup after loading the view.
     _phoneNumberTextField.delegate = self;
+    _phoneNumberTextField.keyboardType = UIKeyboardTypePhonePad;
     [self populateDefaultCountryNameAndCode];
     [[Environment getCurrent] setSignUpFlowNavigationController:self.navigationController];
 
@@ -148,48 +149,60 @@ static NSString *const kCodeSentSegue = @"codeSent";
 
 - (BOOL)textField:(UITextField *)textField
     shouldChangeCharactersInRange:(NSRange)range
-                replacementString:(NSString *)string {
+                replacementString:(NSString *)insertionText {
-    NSString *textBeforeChange = textField.text;
+    
-
+    // Phone numbers takes many forms.
-    // backspacing should skip over formatting characters
+    //
-    UITextPosition *posIfBackspace = [textField positionFromPosition:textField.beginningOfDocument
+    // * We only want to let the user enter decimal digits.
-                                                              offset:(NSInteger)(range.location + range.length)];
+    // * The user shouldn't have to enter hyphen, parentheses or whitespace;
-    UITextRange *rangeIfBackspace = [textField textRangeFromPosition:posIfBackspace toPosition:posIfBackspace];
+    //   the phone number should be formatted automatically.
-    bool isBackspace =
+    // * The user should be able to copy and paste freely.
-        string.length == 0 && range.length == 1 && [rangeIfBackspace isEqual:textField.selectedTextRange];
+    // * Invalid input should be simply ignored.
-    if (isBackspace) {
+    //
-        NSString *digits                       = textBeforeChange.digitsOnly;
+    // We accomplish this by being permissive and trying to "take as much of the user
-        NSUInteger correspondingDeletePosition = [PhoneNumberUtil translateCursorPosition:range.location + range.length
+    // input as possible".
-                                                                                     from:textBeforeChange
+    //
-                                                                                       to:digits
+    // * Always accept deletes.
-                                                                        stickingRightward:true];
+    // * Ignore invalid input.
-        if (correspondingDeletePosition > 0) {
+    // * Take partial input if possible.
-            textBeforeChange = digits;
+    
-            range            = NSMakeRange(correspondingDeletePosition - 1, 1);
+    NSString *oldText = textField.text;
-        }
+    // Construct the new contents of the text field by:
-    }
+    // 1. Determining the "left" substring: the contents of the old text _before_ the deletion range.
-
+    //    Filtering will remove non-decimal digit characters like hyphen "-".
-    // make the proposed change
+    NSString *left = [oldText substringToIndex:range.location].digitsOnly;
-    NSString *textAfterChange            = [textBeforeChange withCharactersInRange:range replacedBy:string];
+    // 2. Determining the "right" substring: the contents of the old text _after_ the deletion range.
-    NSUInteger cursorPositionAfterChange = range.location + string.length;
+    NSString *right = [oldText substringFromIndex:range.location + range.length].digitsOnly;
-
+    // 3. Determining the "center" substring: the contents of the new insertion text.
+    NSString *center = insertionText.digitsOnly;
+    // 4. Construct the "raw" new text by concatenating left, center and right.
+    NSString *textAfterChange = [[left stringByAppendingString:center]
+                                 stringByAppendingString:right];
+    // 5. Construct the "formatted" new text by inserting a hyphen if necessary.
     // reformat the phone number, trying to keep the cursor beside the inserted or deleted digit
-    bool isJustDeletion = string.length == 0;
+    bool isJustDeletion = insertionText.length == 0;
+    NSUInteger cursorPositionAfterChange = left.length + center.length;
     NSString *textAfterReformat =
-        [PhoneNumber bestEffortFormatPartialUserSpecifiedTextToLookLikeAPhoneNumber:textAfterChange.digitsOnly
+    [PhoneNumber bestEffortFormatPartialUserSpecifiedTextToLookLikeAPhoneNumber:textAfterChange
-                                                     withSpecifiedCountryCodeString:_countryCodeButton.titleLabel.text];
+                                                 withSpecifiedCountryCodeString:_countryCodeButton.titleLabel.text];
     NSUInteger cursorPositionAfterReformat = [PhoneNumberUtil translateCursorPosition:cursorPositionAfterChange
                                                                                  from:textAfterChange
                                                                                    to:textAfterReformat
                                                                     stickingRightward:isJustDeletion];
     textField.text = textAfterReformat;
     UITextPosition *pos =
-        [textField positionFromPosition:textField.beginningOfDocument offset:(NSInteger)cursorPositionAfterReformat];
+    [textField positionFromPosition:textField.beginningOfDocument offset:(NSInteger)cursorPositionAfterReformat];
     [textField setSelectedTextRange:[textField textRangeFromPosition:pos toPosition:pos]];
     
     return NO; // inform our caller that we took care of performing the change
 }
 
+- (BOOL)textFieldShouldReturn:(UITextField *)textField {
+    [self sendCodeAction:nil];
+    [textField resignFirstResponder];
+    return NO;
+}
+
 #pragma mark - Unwind segue
 
 - (IBAction)unwindToChangeNumber:(UIStoryboardSegue *)sender {