-(BOOL)isEmoji:(NSString *)character {

    UILabel *characterRender = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 1, 1)];
    characterRender.text = character;
    characterRender.backgroundColor = [UIColor blackColor];//needed to remove subpixel rendering colors
    [characterRender sizeToFit];

    CGRect rect = [characterRender bounds];
    UIGraphicsBeginImageContextWithOptions(rect.size,YES,0.0f);
    CGContextRef contextSnap = UIGraphicsGetCurrentContext();
    [characterRender.layer renderInContext:contextSnap];
    UIImage *capturedImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    CGImageRef imageRef = [capturedImage CGImage];
    NSUInteger width = CGImageGetWidth(imageRef);
    NSUInteger height = CGImageGetHeight(imageRef);
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    unsigned char *rawData = (unsigned char*) calloc(height * width * 4, sizeof(unsigned char));
    NSUInteger bytesPerPixel = 4;
    NSUInteger bytesPerRow = bytesPerPixel * width;
    NSUInteger bitsPerComponent = 8;
    CGContextRef context = CGBitmapContextCreate(rawData, width, height,
                                                 bitsPerComponent, bytesPerRow, colorSpace,
                                                 kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
    CGColorSpaceRelease(colorSpace);

    CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
    CGContextRelease(context);

    BOOL colorPixelFound = NO;

    int x = 0;
    int y = 0;
    while (y < height && !colorPixelFound) {
        while (x < width && !colorPixelFound) {

            NSUInteger byteIndex = (bytesPerRow * y) + x * bytesPerPixel;

            CGFloat red = (CGFloat)rawData[byteIndex];
            CGFloat green = (CGFloat)rawData[byteIndex+1];
            CGFloat blue = (CGFloat)rawData[byteIndex+2];

            CGFloat h, s, b, a;
            UIColor *c = [UIColor colorWithRed:red green:green blue:blue alpha:1.0f];
            [c getHue:&h saturation:&s brightness:&b alpha:&a];

            b /= 255.0f;

            if (b > 0) {
                colorPixelFound = YES;
            }

            x++;
        }
        x=0;
        y++;
    }

    return colorPixelFound;

}

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
    // Detect if an Emoji is in the string "text"
    if(text.isIncludingEmoji) {
        // Show an UIAlertView, or whatever you want here
        return NO;
    }

    return YES;
}

unichar unicodevalue = [text characterAtIndex:0];

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {

    // Get the UTF-16 representation of the text.
    unsigned long length = text.length;
    unichar buffer[length];
    [text getCharacters:buffer];

    // Initialize array to hold our UTF-32 values.
    NSMutableArray *array = [[NSMutableArray alloc] init];

    // Temporary stores for the UTF-32 and UTF-16 values.
    UTF32Char utf32 = 0;
    UTF16Char h16 = 0, l16 = 0;

    for (int i = 0; i < length; i++) {
        unichar surrogate = buffer[i];

        // High surrogate.
        if (0xd800 <= surrogate && surrogate <= 0xd83f) {
            h16 = surrogate;
            continue;
        }
        // Low surrogate.
        else if (0xdc00 <= surrogate && surrogate <= 0xdfff) {
            l16 = surrogate;

            // Convert surrogate pair to UTF-32 encoding.
            utf32 = ((h16 - 0xd800) << 10) + (l16 - 0xdc00) + 0x10000;
        }
        // Normal UTF-16.
        else {
            utf32 = surrogate;
        }

        // Add UTF-32 value to array.
        [array addObject:[NSNumber numberWithUnsignedInteger:utf32]];
    }

    NSLog(@"%@ contains values:", text);

    for (int i = 0; i < array.count; i++) {
        UTF32Char character = (UTF32Char)[[array objectAtIndex:i] unsignedIntegerValue];
        NSLog(@"t- U+%x", character);
    }

    return YES;
}

😎 contains values:
    - U+1f60e

UILabel *characterRender = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 1, 1)];
characterRender.text = character;
characterRender.backgroundColor = [UIColor blackColor];//needed to remove subpixel rendering colors
[characterRender sizeToFit];

CGRect rect = [characterRender bounds];
UIGraphicsBeginImageContextWithOptions(rect.size,YES,0.0f);
CGContextRef contextSnap = UIGraphicsGetCurrentContext();
[characterRender.layer renderInContext:contextSnap];
UIImage *capturedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

CGImageRef imageRef = [capturedImage CGImage];
NSUInteger width = CGImageGetWidth(imageRef);
NSUInteger height = CGImageGetHeight(imageRef);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
unsigned char *rawData =  (unsigned char*) malloc(height * width * 4 * sizeof(unsigned char));
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
CGContextRef context = CGBitmapContextCreate(rawData, width, height,
                                             bitsPerComponent, bytesPerRow, colorSpace,
                                             kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);

CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
CGContextRelease(context);

BOOL colorPixelFound = NO;

int x = 0;
int y = 0;
while (y < height && !colorPixelFound) {
    while (x < width && !colorPixelFound) {

        NSUInteger byteIndex = (bytesPerRow * y) + x * bytesPerPixel;

        CGFloat red = (CGFloat)rawData[byteIndex];
        CGFloat green = (CGFloat)rawData[byteIndex+1];
        CGFloat blue = (CGFloat)rawData[byteIndex+2];

        CGFloat h, s, b, a;
        UIColor *c = [UIColor colorWithRed:red green:green blue:blue alpha:1.0f];
        [c getHue:&h saturation:&s brightness:&b alpha:&a];

        b /= 255.0f;

        if (b > 0) {
            colorPixelFound = YES;
        }

        x++;
    }
    x=0;
    y++;
}

free(rawData);
return colorPixelFound;

[myString canBeConvertedToEncoding:NSASCIIStringEncoding];

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text

{

    // Detect if an Emoji is in the string "text"
    if([text length]==2) {
        // Show an UIAlertView, or whatever you want here
        return YES;
    }
    else
{

       return NO;
}

}