gistfile1.txt

//In RCTTextField.h
@interface RCTTextField : UITextField <UITextFieldDelegate>


//In RCTTextField.m
In Init:
    _eventDispatcher = eventDispatcher;
    //Adding the delegate.
    self.delegate = self;
    [self addTarget:self action:@selector(_textFieldDidChange) forControlEvents:UIControlEventEditingChanged];


- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField
{
  return NO;
}

js

var ToolTipMenu = require('NativeModules').ToolTipMenu;

handleFocus: () => {
   ToolTipMenu.show(this.refs.input.getNodeHandle(), ['x', 'y', 'z']);
}

handleChange: (text) => {
   this.setState({text: text})
}

RCTTextField+ToolTipMenu.h

#import "RCTTextField.h"

@interface RCTTextField (ToolTipMenu)

- (void)tappedMenuItem:(NSString *)text;

@end

RCTTextField+ToolTipMenu.m

#import "UIView+ToolTipMenu.h"

@implementation RCTTextField (ToolTipMenu)

- (void)tappedMenuItem:(NSString *)text {
    self.text = text;
    [self sendActionsForControlEvents:UIControlEventEditingChanged];
}

- (BOOL)canPerformAction:(SEL)action withSender:(id)sender {
    NSString *sel = NSStringFromSelector(action);
    NSRange match = [sel rangeOfString:@"magic_"];
    if (match.location == 0) {
        return YES;
    }
    return NO;
}

- (NSMethodSignature *)methodSignatureForSelector:(SEL)sel {
    if ([super methodSignatureForSelector:sel]) {
        return [super methodSignatureForSelector:sel];
    }
    return [super methodSignatureForSelector:@selector(tappedMenuItem:)];
}

- (void)forwardInvocation:(NSInvocation *)invocation {
    NSString *sel = NSStringFromSelector([invocation selector]);
    NSRange match = [sel rangeOfString:@"magic_"];
    if (match.location == 0) {
        [self tappedMenuItem:[sel substringFromIndex:6]];
    } else {
        [super forwardInvocation:invocation];
    }
}

@end

ToolTipMenu.h

#import <UIKit/UIKit.h>
#import "RCTBridgeModule.h"

@interface ToolTipMenu : NSObject <RCTBridgeModule>

@end

ToolTipMenu.m

#import "ToolTipMenu.h"
#import "UIView+ToolTipMenu.h"
#import "RCTSparseArray.h"
#import "RCTUIManager.h"

@implementation ToolTipMenu

@synthesize bridge = _bridge;

RCT_EXPORT_MODULE()

RCT_EXPORT_METHOD(show:(NSNumber *)reactTag
                  items: (NSArray *)items)
{
    [self.bridge.uiManager addUIBlock:^(RCTUIManager *uiManager, RCTSparseArray *viewRegistry) {
        
        UIView *view = viewRegistry[reactTag];
        if (!view) {
            RCTLogError(@"Cannot find view with tag #%@", reactTag);
            return;
        }
        
        NSArray *buttons = items;
        NSMutableArray *menuItems = [NSMutableArray array];
        for (NSString *buttonText in buttons) {
            NSString *sel = [NSString stringWithFormat:@"magic_%@", buttonText];
            [menuItems addObject:[[UIMenuItem alloc]
                                  initWithTitle:buttonText
                                  action:NSSelectorFromString(sel)]];
        }
        
        UIMenuController *menuCont = [UIMenuController sharedMenuController];
        [menuCont setTargetRect:view.frame inView:view.superview];
        menuCont.arrowDirection = UIMenuControllerArrowDown;
        menuCont.menuItems = menuItems;
        [menuCont setMenuVisible:YES animated:YES];
    }];
}

@end

Solved my issue. Need to add $(SRCROOT)/../react-native/React to the header search paths

@iotashan adding $(SRCROOT)/../react-native/React to the header search paths still displays 'React/RCTTextField.h' file not found for me, any pointers?