braintree payments Errors in BTUIKLocalizedString.h

Question

I tried to implement Braintree iOS v4 in my app and followed steps that given at

https://developers.braintreepayments.com/guides/drop-in/ios/v4

But I got following error when I integrated using this steps.

I want to add drop in UI when I clicked on purchase button.

I used the following code to implement it.

(void)showDropIn:(NSString *)clientTokenOrTokenizationKey {
BTDropInRequest *request = [[BTDropInRequest alloc] init];
BTDropInController *dropIn = [[BTDropInController alloc] initWithAuthorization:clientTokenOrTokenizationKey request:request handler:^(BTDropInController * _Nonnull controller, BTDropInResult * _Nullable result, NSError * _Nullable error) {

    if (error != nil) {
        NSLog(@"ERROR");
    } else if (result.cancelled) {
        NSLog(@"CANCELLED");
    } else {
        // Use the BTDropInResult properties to update your UI
        // result.paymentOptionType
        // result.paymentMethod
        // result.paymentIcon
        // result.paymentDescription
    }
}];
[self presentViewController:dropIn animated:YES completion:nil];
}

Thanks, Hiten