Support `<TextInput keyboardType="numeric" returnKeyType="done" />` on iOS

Summary:
Standard only-numeric (number pad) keyboard on iOS does not have any "Done" or "Enter" button, and this is often very badly hurt user experience.
Usually it can be solved by implementing custom `inputAccessoryView`, but RN does not have built-in support for customizing it.
So, this commit introduced limited support only for "Done" button (returnKeyType="done") and it should suite very well for the vast majority of use cases.
This is highly requested feature, see more details here:
https://github.com/facebook/react-native/issues/1190

Reviewed By: mmmulani

Differential Revision: D5268020

fbshipit-source-id: 90bd5bffac6aaa1fb7c5c2ac539b35b04d45918f

Libraries/Text/RCTBackedTextInputViewProtocol.h

@@ -18,5 +18,6 @@
 @property (nonatomic, assign, readonly) BOOL textWasPasted;
 @property (nonatomic, strong, nullable) UIFont *font;
 @property (nonatomic, assign) UIEdgeInsets textContainerInset;
+@property (nonatomic, strong, nullable) UIView *inputAccessoryView;
 
 @end

Libraries/Text/RCTTextInput.m

@@ -155,4 +155,64 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithFrame:(CGRect)frame)
   [self.backedTextInputView reactFocusIfNeeded];
 }
 
+#pragma mark - Custom Input Accessory View
+
+- (void)didSetProps:(NSArray<NSString *> *)changedProps
+{
+  [self invalidateInputAccessoryView];
+}
+
+- (void)invalidateInputAccessoryView
+{
+#if !TARGET_OS_TV
+  UIView<RCTBackedTextInputViewProtocol> *textInputView = self.backedTextInputView;
+  UIKeyboardType keyboardType = textInputView.keyboardType;
+
+  // These keyboard types (all are number pads) don't have a "Done" button by default,
+  // so we create an `inputAccessoryView` with this button for them.
+  BOOL shouldHaveInputAccesoryView =
+    (
+      keyboardType == UIKeyboardTypeNumberPad ||
+      keyboardType == UIKeyboardTypePhonePad ||
+      keyboardType == UIKeyboardTypeDecimalPad ||
+      keyboardType == UIKeyboardTypeASCIICapableNumberPad
+    ) &&
+    textInputView.returnKeyType == UIReturnKeyDone;
+
+  BOOL hasInputAccesoryView = textInputView.inputAccessoryView != nil;
+
+  if (hasInputAccesoryView == shouldHaveInputAccesoryView) {
+    return;
+  }
+
+  if (shouldHaveInputAccesoryView) {
+    UIToolbar *toolbarView = [[UIToolbar alloc] init];
+    [toolbarView sizeToFit];
+    UIBarButtonItem *flexibleSpace =
+      [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace
+                                                    target:nil
+                                                    action:nil];
+    UIBarButtonItem *doneButton =
+      [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone
+                                                    target:self
+                                                    action:@selector(handleInputAccessoryDoneButton)];
+    toolbarView.items = @[flexibleSpace, doneButton];
+    textInputView.inputAccessoryView = toolbarView;
+  }
+  else {
+    textInputView.inputAccessoryView = nil;
+  }
+
+  // We have to call `reloadInputViews` for focused text inputs to update an accessory view.
+  if (textInputView.isFirstResponder) {
+    [textInputView reloadInputViews];
+  }
+#endif
+}
+
+- (void)handleInputAccessoryDoneButton
+{
+  [self.backedTextInputView endEditing:YES];
+}
+
 @end

RNTester/js/TextInputExample.ios.js

@@ -239,6 +239,7 @@ class BlurOnSubmitExample extends React.Component {
           ref="4"
           style={styles.default}
           keyboardType="numeric"
+          returnKeyType="done"
           placeholder="blurOnSubmit = false"
           blurOnSubmit={false}
           onSubmitEditing={() => this.focusNextField('5')}